Building a Better ASP.NET 1.1 BasePage Framework －－By Chase Thomas
This is a journey on how to build a better Base page. The result of this will be a reusable framework that you can use to create as many Base pages as you like (on many different sites) and still have something that will keep the designers on your team happy. There is a lot to explain so I am breaking this up into several parts starting with the pros and cons of all the approaches I have seen in the past.
Whenever I start a new ASP.NET project I am asked how to make a look and feel that can be reused on all pages of the site. The following are the several approaches I have seen to date:
Have a designer create an HTML template and reuse it in all your pages
- Pros
- No need to recreate the look and feel for each page.
- You can see the look and feel in the designer (big deal) :P
- Cons
- You have to cut and paste the HTML into all your pages.
- You have to maintain all the pages on the site to make the simplest change to your site (not much of an advantage if you ask me).
Comments: This is the approach I have seen done by folks breaking into ASP.NET development. Maintaining sites like this can be a nightmare to say the least. Just pray your client does not ask to change the main look and feel or you will be staying late to get it done…
Create user controls and reuse them on all pages of the site
- Pros
- Simply drag and drop your UI into your new pages and you're done!
- Cons
- Difficult to maintain the site because if you need to remove/add user controls in the Base layout, you have to touch every single page in the site.
- You cannot see the complete look and feel in the designer (again – big deal).
Comments: This is a little better as it makes use of User Controls to centralize the look and feel into separate components but can still be problematic and time consuming when the main look and feel templates need to be added/removed.
Create a base page and hardcode the look and feel into the base page’s OnInit() call
- Pros
- Now we're getting somewhere! We no longer have to maintain the main look and feel across the entire site from each individual page – nor do we need to worry about changes to what elements are added to the main UI because we can change it all from one place.
- Cons
- Very difficult to maintain from a designer perspective (there is no designer support for this approach available), try telling that to your web design team and see what happens.
- You will need to recompile the site if the slightest HTML changes need to be made to the look and feel of the site.
- You should not do this in the
OnInit()because it does not guarantee that your controls will be in place at all phases of execution within your ASP.NET pipeline, the code for generating the base page should be in theCreateChildControls()call. You can forceCreateChildControls()to be called by callingEnsureChildControls().
Comments: We used this approach at two different client sites and it worked well. However when I presented this approach to the client I was at when I wrote this, they balked and wanted to know how to use the visual designer and also how to make changes without compiling and redeploying the site DLL. The next approach is the answer to that question.
Create UserControls for all the sections of your main look and feel, and dynamically load them when your Base page is generated
- Pros
- Designers can alter the HTML of each user control without recompiling the website DLL (unless they add server controls).
- You can make changes to the site’s look and feel without having to change any Base page code (in most cases).
- Cons
- You still have to deal with hardcoding the layout of your controls into the Base page (not cool).
Comments: Although this approach served us well at a client site, we also did not have to worry about them changing the main layout (yet). If that happens I am going to recommend migrating to the next approach which is the approach we are going to be implementing in this series of posts related to this topic.
Build a Basepage base framework in a separate library and reference it in your websites – derive from this Base page and create 1-n Basepages that you can use within your site – make each Base page configurable in the Web.Config file
- Pros
- Designers can alter the layout and look and feel of your site from not only the separate UserControls (which I call base controls or Base controls) but also from the UI layout, which is just another UserControl with placeholders.
- All information about how to generate the HTML header and what styles / scripts to link in and how to set up the body tag can be altered from the web.config.
- Cons
- Still – the full support of having the Base page elements viewable in the designer is not available (you’ll just have to wait for the MasterPages in ASP.NET 2.0).
I mention ASP.NET 2.0 here because the fact that it’s coming soon will make most of the ASP.NET 1.1 techniques in this article obsolete.
Comments – We have used this approach at several clients in the past, it has worked well in the past. One of the things I did not like about it was the lack of centralized configuration and no way to solidify the state objects in our site. It would be nice to have a framework that did all this, that is what we are going to do in this article.
So why write this article? Simple, even though I have seen a lot of companies upgrade their systems to Windows 2003 Server, Windows XP and have embraced using the .NET framework, I do know of a few places that are still stuck using NT 4 Server (even though the client machines are on Windows 2000 Professional which for them are doing well). So yes, using this approach will be invalid when VS.NET 2005 is released to the world. But for the rest of us that get stuck working with old technology, this will be a huge timesaver.
To close this section, I will describe the steps to get started on your own BasePage Framework implementation.
- Create a Class Library Project, call it “BasePageFramework”.
- Add the
System.Webreference. - Create a
SuperBasePageclass and inherit fromSystem.Web.UI.Page. - Create a class and call it
BasePageConfigurationHandler. Implement theSystem.Configuration.ICustomConfigurationHandlerinterface.
Add an XML file so we have a place to put our configuration stuff (this does not need to be part of the project, it’s just a nice place to keep our configuration schema for the Base pages).
Add the following XML to the schema…
/
Part II - Implementing the Configuration Handler
I am going to continue this where we left off in part one, so I am skipping the steps for setting up our Base Page Framework project. Refer to part one to see these steps…
Now I like to centralize everything that is consistent about the pages in my site (i.e. script links, CSS files, body attributes, default name etc...) in one place. I have seen other base pages hard code this stuff which always makes me shudder. (As it should everyone because hard coding things like this should be avoided.)
IMHO it makes sense to place these stuff in a location that can be changed without having to recompile our project. My favorite place for this is the Web.Config file. But since this is a separate framework assembly, it might be a good idea to not use the default appsettings for this application with the configuration information that is going to be used across one to many sites. To solve this problem, we create a custom configuration section for our Base Page Framework. That is the subject of this section.
The first thing we need to do for our base page framework is to create a custom configuration handler to parse the custom configuration settings in our web.config. (See part one for the schema). We do this by implementing the IConfigurationSectionHandler interface which is part of the System.Configuration namespace. This is really easy to do and if you know how to parse XML, you are 4/5th of the way there.
The IConfigurationSectionHandler interface has one method called Create(). Here is the prototype for Create and what each argument is intended to provide:
public object Create(object parent, object configContext, XmlNode section);
Returns
object: this object can be anything you want. I like to create a separate configuration class that holds all my settings and return it so I can cache it for later use. This example will be doing the very same thing.
Parameters
object parentThe parent config section.
object configContextAn
HttpConfigurationContextobject. This is only passed to us when we call it from ASP.NET. As you probably guessed, if you do this out of a Windows app via an app.config file, this parameter will benull.XmlNode sectionThis is our custom configuration section. We will be parsing this to get our configuration settings out of the config file.
Let’s get started…
I like to keep my items in any project logically separated, so create a folder for our configuration stuff. Call it “configuration”. Add a class to this folder and call it BasePageConfigurationSectionHandler. This class will be our configuration handler so implement the IConfigurationSectionHandler interface. Here is the code:
public class BasePageSectionHandler : System.Configuration.IConfigurationSectionHandler { #region IConfigurationSectionHandler Members public object Create(object parent, object configContext, XmlNode section) { System.Xml.XmlNodeList pages = section.SelectNodes("page"); return new BasePagesConfiguration(pages); } #endregion }
In this implementation, we are going to return the next class we are going to create which is the BasePagesConfiguration class. If you look at the schema for our configuration you will see that there can be 1:n page elements. This is because you can have more than one base page in your site. So if you guessed that BasePagesConfiguration is a collectionbase object, then you guessed right. We are going to need to implement this object next. Here is the code:
public class BasePagesConfiguration : System.Collections.ReadOnlyCollectionBase { public BasePagesConfiguration(System.Xml.XmlNodeList pages) { foreach(System.Xml.XmlNode page in pages) this.InnerList.Add(new BasePageConfiguration(page)); } public BasePageConfiguration this[string pageName] { get { foreach(BasePageConfiguration pge in this.InnerList) { if(pge.Name == pageName) return pge; } throw new System.InvalidOperationException("The base page ID " + pageName + " could not be found in" + " the current configuration"); } } }
The indexer of this object returns a single BasePageConfiguration object via a key value. I am not too concerned with how quickly the collection returns individual configuration objects so I am using a simple loop. The reason we don’t really care about performance here is because our base page will internally cache its configuration object so it does not have to keep going out to the config file every time it gets requested.
Finally we get to the configuration object. We are going to aptly call this BasePageConfiguration. Create the BasePageConfiguration class in your project. Here is the code. I am going to assume that you know how to parse XML documents so I am not going to go into detail on how that works. I will just explain what each field of this object is for.
public class BasePageConfiguration { private string _pageName = string.Empty; private NameValueCollection _bodyAttributes = new NameValueCollection(); private string _defaultTitle = string.Empty; private NameValueCollection _scriptFiles = new NameValueCollection(); private NameValueCollection _cssFiles = new NameValueCollection(); private NameValueCollection _metaTags = new NameValueCollection(); public BasePageConfiguration(XmlNode xml) { //parse the xml passed to us and set the configuration state //first get the name of this page System.Xml.XmlAttribute pageName = (XmlAttribute)xml.Attributes.GetNamedItem("name"); System.Xml.XmlAttribute defaultTitle = (XmlAttribute)xml.Attributes.GetNamedItem("defaultTitle"); if(defaultTitle != null) _defaultTitle = defaultTitle.Value; else _defaultTitle = string.Empty; if(pageName != null) _pageName = pageName.Value; else throw new System.Configuration.ConfigurationException("The name" + " attribute is required on all basepage configuration entries."); //get the body tag attributes System.Xml.XmlNodeList bodyAttrib = xml.SelectNodes("body/attribute"); foreach(XmlNode attr in bodyAttrib) { XmlAttribute name = (XmlAttribute)attr.Attributes.GetNamedItem("name"); XmlAttribute val = (XmlAttribute)attr.Attributes.GetNamedItem("value"); if(name != null && val != null) { _bodyAttributes.Add(name.Value,val.Value); } } //get the site settings System.Xml.XmlNode title = xml.SelectSingleNode("site/title"); if(title != null) { XmlAttribute val = (XmlAttribute)title.Attributes.GetNamedItem("value"); if(val != null) _defaultTitle = val.Value; } //get the main page links System.Xml.XmlNodeList cssFiles = xml.SelectNodes("links/css"); foreach(XmlNode css in cssFiles) { XmlAttribute file = (XmlAttribute)css.Attributes.GetNamedItem("file"); XmlAttribute path = (XmlAttribute)css.Attributes.GetNamedItem("path"); if(file != null && path != null) _cssFiles.Add(file.Value,path.Value); } System.Xml.XmlNodeList scriptFiles = xml.SelectNodes("links/script"); foreach(XmlNode script in scriptFiles) { XmlAttribute file = (XmlAttribute)script.Attributes.GetNamedItem("file"); XmlAttribute path = (XmlAttribute)script.Attributes.GetNamedItem("path"); if(file != null && path != null) _scriptFiles.Add(file.Value,path.Value); } // get the place holder settings so we can see what user // controls to load into our base page placeholders System.Xml.XmlNodeList metaTags = xml.SelectNodes("metatags/meta"); foreach(XmlNode tag in metaTags) { XmlAttribute name = (XmlAttribute)tag.Attributes.GetNamedItem("name"); XmlAttribute content = (XmlAttribute)tag.Attributes.GetNamedItem("Content"); this._metaTags.Add(name.Value,content.Value); } } //do not allow outside access to the individual //values of the configuration public NameValueCollection BodyAttributes{get{return _bodyAttributes;}} public HorizontalAlign SiteAlignment{get{return _alignment;}} public string DefaultTitle{get{return _defaultTitle;}} public NameValueCollection Scripts{get{return _scriptFiles;}} public NameValueCollection StyleSheets{get{return _cssFiles;}} public string Name{get{return _pageName;}} public NameValueCollection MetaTags{get{return _metaTags;}} }
_pageNameThis is the ID of our base page. Each base page in the system must have a unique name so its configuration can be located in the config file (more on this later when we get into implementing the actual base page Base).
private NameValueCollection _bodyAttributesThese are the individual body attribute tags that will go into each and every one of our pages. They are injected into the HTML in the base page Base
OnAddParsedSubObject()call (many thanks to Michael Earls for showing me the light on this one).private string _defaultTitleThis is the default title that will be used on all pages of our site. Should the HTML designer not put anything into the
</code> tag we will replace that blank value with this one.</p></li> <li><code><span class="cs-keyword">private</span> NameValueCollection _scriptFiles</code> <p>This is a list of script links that will be placed inside the <code><head></code> tags.</p></li> <li><code><span class="cs-keyword">private</span> NameValueCollection _cssFiles</code> <p>This is a list of stylesheet links that will be placed inside the <code><head></code> tags.</p></li> <li><code><span class="cs-keyword">private</span> NameValueCollection _metaTags</code> <p>This is a list of default metatags that will appear in all pages of our site.</p></li> </ul> <p>Finally as you can see, the configuration is a read only object. This is logical because it will only get its values from the configuration file when the object is created by the configuration handler.</p> <p>Using this handler is easy. To create an instance of the configuration handler, you need to call <code>GetConfig()</code> in your <code>ConfigurationSettings</code> object.</p> <pre>Configuration.BasePagesConfiguration baseConfiguration = (Configuration.BasePagesConfiguration) System.Configuration.ConfigurationSettings.GetConfig( <span class="cpp-string">"base.configuration"</span>);</pre> <p><b>Returns</b>: the appropriate configuration object based on your section in the <code>configSections</code> tag. See the following snippet taken from the schema we created in part one.</p> <pre><configSections> <section name="base.configuration" type="BasePageFramework.Configuration.BasePageSectionHandler, BasePageFramework"/> </configSections></pre> <p>The object that gets returned here is whatever you decided to return from your <code>IConfigurationSectionHandler.Create</code> implementation. In this case, it is our <code>ReadOnlyCollectionBase</code> "<code>BasePagesConfiguration</code>" object that contains the individual <code>BasePageConfiguration</code> objects for our site.</p> <p>The name attribute of this configuration section is the configuration section in your <i>.config</i> file. The type is the fully qualified object name that implements the <code>IConfiguraitonSectionHandler</code> interface, along with the name of the assembly this object resides in, separated by a comma. If you are referencing a strong named assembly then you need to put all four parts of the assembly name into the type attribute like this (taken from <i>System.dll</i>):</p> <pre><section name="MyCustomSection" type="System.Configuration.NameValueSectionHandler,system, Version=1.0.3300.0, Culture=neutral, PublicKeyToken=b77a5c561934e089,custom=null" /></pre> <p>As you can see, you put the remaining four parts of the strong name into the type tag after your DLL name (separated by commas).</p> <p>In part 3, we are going to get started on the implementation of the <code>SuperBasePage</code> itself. To close in part 4, I am going to show you how to throw in some extra features that wrap standard site state management. The objects are classes that implement the <code>ISmartQueryString</code>, <code>ISmartSession</code>, and <code>ISmartApplication</code> interfaces.</p> <h2>Part III - Implementing the SuperBasePage</h2> <p>I am going to continue this at the point where we left off creating the <code>BasePageConfiguration</code> class. In this part, we are going to implement the <code>SuperBasePage</code> that will be used in all the derived Base pages of your site. It is useful to have multiple Base pages in your site because you might want to have a layout for printer friendly pages, popup windows, dialogs, etc…</p> <p>This part is a bit on the long side, I will try to keep it as short as possible given the amount of stuff that’s happening here. I will also post some UML class and sequence diagrams in the next part so there will be some decent docs to go with it.</p> <p>The <code>SuperBasePage</code> is actually two separate classes and a user control that implements a custom interface all working together to form a template. They are declared as follows:</p> <pre><span class="cs-keyword">public</span> <span class="cs-keyword">interface</span> IBaseTemplate { PlaceHolder ContentArea {<span class="cs-keyword">get</span>;} } <span class="cs-keyword">public</span> <span class="cs-keyword">class</span> SuperBasePage : WebUI.Page { <span class="cs-keyword">private</span> BaseServerForm _baseForm = <span class="cs-keyword">null</span>; <span class="cs-comment">//new SuperBasePage("BASE_FORM");</span> <span class="cs-comment">//the form tag where we place all our webserver controls</span> <span class="cs-keyword">private</span> Configuration.BasePageConfiguration _config = <span class="cs-keyword">null</span>; …</pre> <p>These three items when properly used will not only allow us to quickly create Base pages that can be configured from the <i>web.config</i>, but also allows us to leave the HTML in our individual pages on our site. I have seen other frameworks / Base page concepts where you need to remove the <code>HTML</code>, <code>HEAD</code>, <code>TITLE</code>, <code>BODY</code>, and <code>FORM</code> tags in order to be useable. We will not be doing that here. It is important that we keep that part intact for two reasons:</p> <ol> <li>Designers can understand it better so you do not need to worry about whether or not they will replace these tags in error, and more importantly, </li> <li>Keeping these tags in each page allows us to override what is placed in the <i>web.config</i> (like trace directives etc… our framework follows the same pattern). </li> </ol> <p>To start with, we need to look at the existing objects at our disposal in the <code>System.Web</code> namespace. The ones we are interested in right now are <code>System.Web.UI.Page</code> and <code>System.Web.UI.HtmlControls.HtmlForm</code>. The latter of the two is what we will be worrying about first.</p> <p>The <code>HtmlForm</code> when set with a server tag becomes the heart of the ubiquitous ASP.NET webform. You cannot instantiate server controls on your page without it. Herein lies our problem, how can we get our form which we have to define on each page to behave the same by displaying the same outlying content with unique content for each page, and more importantly, how do we get the content from our page to actually nest itself within this form’s content area? What I have seen done in past Base pages I have developed is to “move” the content from each of their pages to a specified “content area” in their Base page class. We are still doing that here but in a more discreet way. And, as I have already mentioned, most of the examples force you to delete the HTML header and footer along with the <code>Form</code> tag from your page before using it (try explaining that to a web-designer and see what they do).</p> <p>There must be a better way, so instead of moving the content from our derived page to the Base page’s content area, we will do a little switcharoo with the <code>HtmlForm</code> and change it into a form that has the following functionality…</p> <ol> <li>Has a reference to a template that defines the layout for all our pages. </li> <li>This form needs to know how to construct it in such a way that when you pass it an existing form, it can take the place of the old form with one important difference – it will have the functionality for placing our individual pages' content where it all belongs. </li> </ol> <p>So in essence instead of our Base page high-jacking the content of each page, our Base page receives an <code>HtmlForm</code> and makes it work in such a way that allows us to set content wherever we want from a given template that the form will initialize when it gets created. You will notice that our <code>BaseServerForm</code> is nothing more than a plain old <code>HtmlForm</code> with a template reference. The following is the code for our Base server form…</p> <pre><span class="cs-keyword">public</span> <span class="cs-keyword">class</span> BaseServerForm : HtmlUI.HtmlForm { <span class="cs-keyword">private</span> WebCtlUI.PlaceHolder _uiTemplatePlcHldr = <span class="cs-keyword">new</span> WebCtlUI.PlaceHolder(); <span class="cs-keyword">internal</span> BaseServerForm(HtmlUI.HtmlForm oldFrm,IBaseTemplate uiTemplate) { <span class="cs-keyword">foreach</span>(<span class="cs-keyword">string</span> key <span class="cs-keyword">in</span> oldFrm.Attributes.Keys) <span class="cs-keyword">this</span>.Attributes.Add(key,oldFrm.Attributes[key]); System.Type frmTp = oldFrm.GetType(); <span class="cs-comment">// move the controls first - so they are located</span> <span class="cs-comment">// in the main form before we</span> <span class="cs-comment">// rip apart the htmlform via reflection</span> <span class="cs-keyword">while</span>(oldFrm.Controls.Count > <span class="cs-literal">0</span>) uiTemplate.ContentArea.Controls.Add( (System.Web.UI.Control)oldFrm.Controls[<span class="cs-literal">0</span>]); <span class="cs-comment">//copy the old form's values into our new form...</span> <span class="cs-keyword">foreach</span>(FieldInfo fields <span class="cs-keyword">in</span> frmTp.GetFields(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance)) <span class="cs-keyword">this</span>.GetType().GetField(fields.Name, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance).SetValue(<span class="cs-keyword">this</span>, fields.GetValue(oldFrm)); <span class="cs-keyword">this</span>._uiTemplatePlcHldr.Controls.Add( (System.Web.UI.Control)uiTemplate); <span class="cs-keyword">this</span>.Controls.Add((System.Web.UI.Control) <span class="cs-keyword">this</span>._uiTemplatePlcHldr); } <span class="cs-keyword">public</span> IBaseTemplate BaseTemplate { <span class="cs-keyword">get</span>{<span class="cs-keyword">return</span> (IBaseTemplate)_uiTemplatePlcHldr.Controls[<span class="cs-literal">0</span>];} } }</pre> <p>The constructor of this class takes two things, an <code>HtmlForm</code> object and a reference to something called an <code>IBaseTemplate</code>. This is how you will implement the <code>IBaseTemplate</code> in your code…</p> <pre><span class="cs-keyword">public</span> <span class="cs-keyword">class</span> AcmeBaseTemplate : System.Web.UI.UserControl, BasePageFramework.IBaseTemplate { <span class="cs-keyword">protected</span> System.Web.UI.WebControls.PlaceHolder _content; <span class="cs-keyword">protected</span> System.Web.UI.WebControls.PlaceHolder _leftNav; <span class="cs-keyword">public</span> PlaceHolder LeftNavigation {<span class="cs-keyword">get</span>{<span class="cs-keyword">return</span> _leftNav;}} <span class="cs-preprocessor">#region IBaseTemplate Members</span> <span class="cs-keyword">public</span> PlaceHolder ContentArea { <span class="cs-keyword">get</span> { <span class="cs-keyword">return</span> _content; } } <span class="cs-preprocessor">#endregion</span></pre> <p>This template interface is how I get around a limitation in another framework that does almost the same thing this one does. Why define an interface to be used for our complete Base layout if we may want to change that layout in the future? What I think makes sense is to define a class that exposes our Base page’s content areas so we can change what they contain at will. Plus, it would also be nice to create different layouts with access to all areas in our page. This will also allow us to dynamically change our layouts at runtime under certain conditions. Finally, it would also be really nice if our designers could change the look of the Base page without going into the code but instead by using the designer. That is where using a UserControl (that implements our <code>IBaseTemplate</code> interface) comes in handy.</p> <p>There is one gotcha however, we can’t be sure of what the template developer is going to call the area to place our content. We really need to know this so we can relocate the pages controls to this area in a nice seamless and discreet manner. This is where the <code>IBaseTemplate</code> interface comes in to play. As you can see in the above example, we define a placeholder where our derived pages' content will go in the Base page and return it through this interface's only property “<code>ContentArea</code>” (which coincidentally returns a placeholder for our content). Now our Base page will have a contract with the UserControl that says “I will assume responsibility of locating the controls where they belong so you don’t have too”.</p> <p>You will see later on in the Base page definition why we need to expose the other placeholders in our user control to the outside world via properties as I have done in the above example.</p> <p>The <code>BaseServerForm</code> class doesn’t do much other than encapsulate the movement of our page's content to the template’s content area (and perform the role of server form) so besides loading a UI template, it is basically just a server form with a layout defined. I should also note that we do not want anything but the Base page creating a <code>BaseServerForm</code>, so we hide the constructor from the outside world by declaring it <code><span class="cs-keyword">internal</span></code>. This is because the Base page is the only object that should ever need to crate a <code>BaseServerForm</code>. However, we do want developers to be able to reference the form in case they decide to change something programmatically before the request is handled. I had to resort to using reflection to rip apart the old <code>HtmlForm</code>’s private values and copy them to our <code>BaseServerForm</code>. We could have used a “has-a” relationship with the <code>HtmlForm</code> but that seemed a bit on the clunky side, therefore I made it an "is-a" relationship to make its relationship with our pages seamless. Also note that it is critical that we move the control tree and attributes of the old <code>HtmlForm</code> to our new <code>BaseServerForm</code> before we use reflection to get any <code><span class="cs-keyword">internal</span></code> values. We can get to the control tree just fine, we don’t need to use reflection to get to it. I normally do not like using reflection unless absolutely required. I like to think of reflection like I think of Duct Tape, it’s a tool that has a noble purpose… But when used “creatively” you can end up really shooting yourself in the foot (if you will forgive the old C cliché).</p> <p>Now that we have our <code>BaseServerForm</code> class defined, we need to define the super base page from which we will derive all our sites' base pages. Here is the code…</p> <pre><span class="cs-keyword">public</span> <span class="cs-keyword">class</span> SuperBasePage : WebUI.Page { <span class="cs-preprocessor"> #region Constants</span> <span class="cs-comment">//large string builder initial buffer siz</span> <span class="cs-keyword">private</span> <span class="cs-keyword">const</span> <span class="cs-keyword">int</span> LG_STR_BUFFER_SZ = <span class="cs-literal">512</span>; <span class="cs-comment">//medium string builder inital buffer size</span> <span class="cs-keyword">private</span> <span class="cs-keyword">const</span> <span class="cs-keyword">int</span> MD_STR_BUFFER_SZ = <span class="cs-literal">256</span>; <span class="cs-comment">//small (default) string builder buffer size</span> <span class="cs-keyword">private</span> <span class="cs-keyword">const</span> <span class="cs-keyword">int</span> SM_STR_BUFFER_SZ = <span class="cs-literal">128</span>; <span class="cs-keyword">private</span> <span class="cs-keyword">const</span> <span class="cs-keyword">string</span> OPEN_TITLE_TAG = <span class="cpp-string">""</span>; <span class="cs-keyword">private</span> <span class="cs-keyword">const</span> <span class="cs-keyword">string</span> OPEN_HEAD_TAG = <span class="cpp-string">""</span>; <span class="cs-keyword">private</span> <span class="cs-keyword">const</span> <span class="cs-keyword">string</span> CLOSE_HEAD_TAG = <span class="cpp-string">""</span>; <span class="cs-keyword">private</span> <span class="cs-keyword">const</span> <span class="cs-keyword">string</span> OPEN_HTML_TAG = <span class="cpp-string">""</span>; <span class="cs-keyword">private</span> <span class="cs-keyword">const</span> <span class="cs-keyword">int</span> DEFAULT_LINK_WIDTH = <span class="cs-literal">20</span>; <span class="cs-comment">//this is used to estimage the number of characters </span> <span class="cs-comment">//to reserve space for in our string builders </span> <span class="cs-comment">//in an attempt to maximize efficency</span> <span class="cs-preprocessor"> #endregion</span> <span class="cs-preprocessor"> #region SuperBasePage Members</span> <span class="cs-comment">//our form sits in this placeholder</span> <span class="cs-keyword">private</span> WebCtl.PlaceHolder _serverFormPlcHldr = <span class="cs-keyword">new</span> WebCtl.PlaceHolder(); <span class="cs-comment">//the title of the page (displayed in the caption bar)</span> <span class="cs-keyword">private</span> <span class="cs-keyword">string</span> _title = <span class="cs-keyword">string</span>.Empty; <span class="cs-keyword">private</span> BaseServerForm _baseForm = <span class="cs-keyword">null</span>; <span class="cs-comment">//new SuperBasePage("BASE_FORM");</span> <span class="cs-comment">//the form tag where we place all our webserver controls</span> <span class="cs-keyword">private</span> Configuration.BasePageConfiguration _config = <span class="cs-keyword">null</span>; <span class="cs-keyword">private</span> <span class="cs-keyword">string</span> _basePageName = <span class="cs-keyword">string</span>.Empty; <span class="cs-keyword">private</span> ISmartQueryString _smartQueryString = <span class="cs-keyword">null</span>; <span class="cs-keyword">private</span> ISmartSession _smartSession = <span class="cs-keyword">null</span>; <span class="cs-keyword">private</span> ISmartApplication _smartApp = <span class="cs-keyword">null</span>; <span class="cs-preprocessor"> #endregion</span> <span class="cs-preprocessor"> #region Properties</span> <span class="cs-keyword">public</span> <span class="cs-keyword">string</span> Title { <span class="cs-keyword">get</span>{<span class="cs-keyword">return</span> <span class="cs-keyword">this</span>._title;} <span class="cs-keyword">set</span>{<span class="cs-keyword">this</span>._title = value;} } <span class="cs-keyword">public</span> BaseServerForm BaseForm {<span class="cs-keyword">get</span>{<span class="cs-keyword">return</span> <span class="cs-keyword">this</span>._baseForm;}} <span class="cs-keyword">public</span> IBaseTemplate MainUITemplate {<span class="cs-keyword">get</span>{<span class="cs-keyword">return</span> <span class="cs-keyword">this</span>._baseForm.BaseTemplate;}} <span class="cs-keyword">public</span> ISmartSession SmartSession { <span class="cs-keyword">get</span>{ <span class="cs-keyword">if</span>(<span class="cs-keyword">this</span>._smartSession == <span class="cs-keyword">null</span>) <span class="cs-keyword">throw</span> <span class="cs-keyword">new</span> InvalidOperationException(<span class="cpp-string">"You must"</span> + <span class="cpp-string">" initialize the smart session state"</span> + <span class="cpp-string">" before you can reference it"</span>); <span class="cs-keyword">else</span> <span class="cs-keyword">return</span> <span class="cs-keyword">this</span>._smartSession; } } <span class="cs-keyword">public</span> ISmartApplication SmartApplication { <span class="cs-keyword">get</span>{ <span class="cs-keyword">if</span>(<span class="cs-keyword">this</span>._smartApp == <span class="cs-keyword">null</span>) <span class="cs-keyword">throw</span> <span class="cs-keyword">new</span> InvalidOperationException(<span class="cpp-string">"You must"</span> + <span class="cpp-string">" initialize the smart application state"</span> + <span class="cpp-string">" before you can reference it"</span>); <span class="cs-keyword">else</span> <span class="cs-keyword">return</span> <span class="cs-keyword">this</span>._smartApp; } } <span class="cs-keyword">public</span> ISmartQueryString SmartQueryString { <span class="cs-keyword">get</span> { <span class="cs-keyword">if</span>(<span class="cs-keyword">this</span>._smartQueryString == <span class="cs-keyword">null</span>) <span class="cs-keyword">throw</span> <span class="cs-keyword">new</span> InvalidOperationException(<span class="cpp-string">"You must"</span> + <span class="cpp-string">" initialize the smart query string"</span> + <span class="cpp-string">" before you can reference it"</span>); <span class="cs-keyword">else</span> <span class="cs-keyword">return</span> <span class="cs-keyword">this</span>._smartQueryString; } } <span class="cs-preprocessor"> #endregion</span> <span class="cs-keyword">protected</span> <span class="cs-keyword">override</span> <span class="cs-keyword">void</span> CreateChildControls() { InitSmartQueryString(<span class="cs-keyword">ref</span> <span class="cs-keyword">this</span>._smartQueryString); <span class="cs-keyword">if</span>(<span class="cs-keyword">this</span>._smartQueryString != <span class="cs-keyword">null</span>) <span class="cs-keyword">this</span>._smartQueryString.SetQueryStringInfo(<span class="cs-keyword">this</span>.Page); InitSmartSession(<span class="cs-keyword">ref</span> <span class="cs-keyword">this</span>._smartSession); <span class="cs-keyword">if</span>(<span class="cs-keyword">this</span>._smartSession != <span class="cs-keyword">null</span>) <span class="cs-keyword">this</span>._smartSession.SetSessionState(<span class="cs-keyword">this</span>.Page.Session); <span class="cs-comment">//allows us to set the base page state from </span> <span class="cs-comment">//the child page before any rendering of the base page occurs</span> BasePreRender(<span class="cs-keyword">this</span>._baseForm); <span class="cs-comment">//call the virutal method to allow the base page </span> <span class="cs-comment">//to set the appropriate usercontrols into the base template</span> LoadTemplatePanels(); } <span class="cs-keyword">protected</span> <span class="cs-keyword">override</span> <span class="cs-keyword">void</span> OnInit(EventArgs e) { <span class="cs-keyword">this</span>.EnsureChildControls(); <span class="cs-keyword">base</span>.OnInit (e); } <span class="cs-keyword">protected</span> <span class="cs-keyword">override</span> <span class="cs-keyword">void</span> AddParsedSubObject(Object obj) { <span class="cs-comment">//put all the configuration extras into our html header here</span> <span class="cs-comment">//make sure you modify the body tag as well since it is also </span> <span class="cs-comment">//editable from our custom configuration section</span> <span class="cs-keyword">if</span>(obj <span class="cs-keyword">is</span> HtmlCtl.HtmlForm) { BasePageFramework.IBaseTemplate tmplt = <span class="cs-keyword">null</span>; <span class="cs-keyword">this</span>.LoadBaseUITemplate(<span class="cs-keyword">ref</span> tmplt); <span class="cs-keyword">if</span>(tmplt == <span class="cs-keyword">null</span>) <span class="cs-keyword">throw</span> <span class="cs-keyword">new</span> InvalidOperationException(<span class="cpp-string">"Unable to"</span> + <span class="cpp-string">" load the base UI Template"</span>); <span class="cs-keyword">this</span>._baseForm = <span class="cs-keyword">new</span> BaseServerForm((HtmlCtl.HtmlForm)obj, tmplt); <span class="cs-comment">//replace the object reference with </span> <span class="cs-comment">//our own "base server form"</span> obj = <span class="cs-keyword">this</span>._baseForm; } <span class="cs-keyword">if</span>(obj <span class="cs-keyword">is</span> Web.UI.LiteralControl) { Web.UI.LiteralControl htmlHeader = (Web.UI.LiteralControl)obj; <span class="cs-comment">//we only need to do this processing when we are in the header</span> <span class="cs-keyword">if</span>(htmlHeader.Text.IndexOf(OPEN_HTML_TAG)>=<span class="cs-literal">0</span>) { <span class="cs-comment">//we are going to need the stuff from </span> <span class="cs-comment">//the configuration now so load it up...</span> ConfigLoadingArgs cfgParam = <span class="cs-keyword">new</span> ConfigLoadingArgs(); InitializeConfiguration(<span class="cs-keyword">ref</span> cfgParam); <span class="cs-keyword">this</span>._config = (Configuration.BasePageConfiguration) Cache[<span class="cpp-string">"BASE_CONFIGURATION_"</span> + cfgParam.BasePageID]; <span class="cs-keyword">if</span>(<span class="cs-keyword">this</span>._config == <span class="cs-keyword">null</span>) InitFromConfiguration(cfgParam.BasePageID); <span class="cs-keyword">if</span>(<span class="cs-keyword">this</span>._config != <span class="cs-keyword">null</span>) { System.Text.StringBuilder htmlBuilder = <span class="cs-keyword">new</span> System.Text.StringBuilder(htmlHeader.Text.Length*<span class="cs-literal">2</span>); htmlBuilder.Append(htmlHeader.Text); <span class="cs-comment">//check to see if the current literal control </span> <span class="cs-comment">//being passed to us is actually </span> <span class="cs-comment">//the HTML header - if it is then we need </span> <span class="cs-comment">//to add any values from the custom web.config settings</span> <span class="cs-comment">//if the current page has any of the same </span> <span class="cs-comment">//values in the body tag or any inline scripts -</span> <span class="cs-comment">//then we need to allow the page to override </span> <span class="cs-comment">//the web.config settings - </span> <span class="cs-comment">//this is in following with the</span> <span class="cs-comment">//same pattern for everything in ASP.NET </span> <span class="cs-comment">//(machine.config-web.config-page...)</span> <span class="cs-comment">//see if the title is filled in if not </span> <span class="cs-comment">//insert the default title </span> <span class="cs-comment">//if the title tag is missing then add one now</span> <span class="cs-keyword">int</span> openingTitleTagOffset = htmlHeader.Text.ToUpper().IndexOf( OPEN_TITLE_TAG,<span class="cs-literal">0</span>,htmlHeader.Text.Length); <span class="cs-keyword">int</span> endTitleTagOffset = htmlHeader.Text.ToUpper().IndexOf( CLOSE_TITLE_TAG,<span class="cs-literal">0</span>,htmlHeader.Text.Length); endTitleTagOffset -= CLOSE_TITLE_TAG.Length-<span class="cs-literal">1</span>; <span class="cs-keyword">int</span> titleLen = htmlHeader.Text.Substring(openingTitleTagOffset, endTitleTagOffset -openingTitleTagOffset).Length; <span class="cs-comment">//get the length of our title</span> <span class="cs-keyword">if</span>(openingTitleTagOffset >= <span class="cs-literal">0</span>) { <span class="cs-comment">//check the length of our title</span> <span class="cs-comment">//if the title is missing then add the default one</span> <span class="cs-keyword">if</span>(titleLen == <span class="cs-literal">0</span>) htmlBuilder.Insert(openingTitleTagOffset+ OPEN_TITLE_TAG.Length, <span class="cs-keyword">this</span>._config.DefaultTitle); } <span class="cs-keyword">else</span> { <span class="cs-keyword">int</span> openHeadTagOffset = htmlHeader.Text.ToUpper().IndexOf(OPEN_HEAD_TAG, <span class="cs-literal">0</span>,htmlHeader.Text.Length); <span class="cs-comment">//if the head tag is missing then add it </span> <span class="cs-comment">//otherwise just insert the default title if needed</span> <span class="cs-comment">//create another string Builder to handle </span> <span class="cs-comment">//our missing header/title tag</span> System.Text.StringBuilder subHtml = <span class="cs-keyword">new</span> System.Text.StringBuilder((OPEN_HEAD_TAG.Length + CLOSE_HEAD_TAG.Length + OPEN_TITLE_TAG.Length + CLOSE_TITLE_TAG.Length) +_config.DefaultTitle.Length); <span class="cs-keyword">if</span>(openHeadTagOffset == -<span class="cs-literal">1</span>) { subHtml.Append(OPEN_HEAD_TAG); subHtml.Append(OPEN_TITLE_TAG); subHtml.Append(_config.DefaultTitle); subHtml.Append(CLOSE_TITLE_TAG); subHtml.Append(CLOSE_HEAD_TAG); <span class="cs-comment">//insert the output right </span> <span class="cs-comment">//after the opening HTML tag</span> htmlBuilder.Insert(OPEN_HTML_TAG.Length, subHtml.ToString()); } <span class="cs-keyword">else</span> { subHtml.Append(OPEN_TITLE_TAG); subHtml.Append(_config.DefaultTitle); subHtml.Append(CLOSE_TITLE_TAG); <span class="cs-comment">//insert the output right after </span> <span class="cs-comment">//the opening Head Tag</span> htmlBuilder.Insert(openHeadTagOffset, subHtml.ToString()); } } <span class="cs-comment">//insert our configuration metatags and </span> <span class="cs-comment">//scripts/links after the closing title tag...</span> <span class="cs-comment">//int closingTitleTagOffset = </span> htmlBuilder.ToString().ToUpper().IndexOf(CLOSE_HEAD_TAG, <span class="cs-literal">0</span>,htmlBuilder.ToString().Length); htmlBuilder.Replace(CLOSE_HEAD_TAG, GetWebConfigLinks(htmlBuilder.ToString())); RenderBodyTagLinks(htmlBuilder); <span class="cs-comment">//replace the text in the literal </span> <span class="cs-comment">//control with our new header</span> htmlHeader.Text = htmlBuilder.ToString(); } } } <span class="cs-keyword">this</span>.Controls.Add((System.Web.UI.Control)obj); } <span class="cs-preprocessor"> #region HTML Header Parsing Code</span> <span class="cs-keyword">private</span> <span class="cs-keyword">void</span> RenderBodyTagLinks(System.Text.StringBuilder htmlBuilder) { <span class="cs-comment">//rip out the body tag and replace it with our own</span> <span class="cs-comment">//that has the attributes from the web config file</span> <span class="cs-comment">//but allows the individual pages to override </span> <span class="cs-comment">//these settings at the page level</span> <span class="cs-keyword">string</span> bodyTag = htmlBuilder.ToString(); <span class="cs-keyword">int</span> bodyTagOffset = bodyTag.ToUpper().IndexOf(<span class="cpp-string">"<BODY"</span>); bodyTag = bodyTag.Substring(bodyTagOffset, bodyTag.Length - bodyTagOffset); <span class="cs-comment">//create the attributes that will be dumped into the body tag</span> <span class="cs-comment">//make sure it is not already in the body before entering it</span> <span class="cs-comment">//if it is in the body then throw it out so the individual page</span> <span class="cs-comment">//can override the web.config's settings</span> System.Text.StringBuilder bodyTagBuilder = <span class="cs-keyword">new</span> System.Text.StringBuilder(SM_STR_BUFFER_SZ); bodyTagBuilder.Append(<span class="cpp-string">" foreach(string attribute in _config.BodyAttributes.Keys) if(bodyTag.IndexOf(attribute) == -1) { bodyTagBuilder.Append("</span> <span class="cpp-string">"); bodyTagBuilder.Append(attribute); bodyTagBuilder.Append("</span>=/<span class="cpp-string">""</span>); bodyTagBuilder.Append( _config.BodyAttributes.Get(attribute)); bodyTagBuilder.Append(<span class="cpp-string">"/"</span> <span class="cpp-string">"); } //append the global body tag attributes to the //end of the current attribute list in our body tag string newAttribList = bodyTag.Substring(5,bodyTag.Length-6); //remove the opening body tag and closing bracket //get the current attributes out of the old body tag //and add them to our bodytagbuilder bodyTagBuilder.Append("</span> <span class="cpp-string">"); bodyTagBuilder.Append(newAttribList); int bodytagoffset = htmlBuilder.ToString().IndexOf(bodyTag); //remove the old body tag from our string builder htmlBuilder.Remove(bodytagoffset,htmlBuilder.Length-bodytagoffset); string output = htmlBuilder.ToString(); htmlBuilder.Append(bodyTagBuilder.ToString()); } //takes the existing script links and returns a new string //containing the existing links merged with the ones in the web.config private string GetWebConfigLinks(string oldHtml) { System.Text.StringBuilder subHtml = new System.Text.StringBuilder((_config.Scripts.Count* DEFAULT_LINK_WIDTH)+CLOSE_HEAD_TAG.Length); this.GetMetaTags(subHtml,oldHtml); this.GetStyleSheetLinks(subHtml); this.GetScriptLinks(subHtml); subHtml.Append("</span>/r/n/t<span class="cpp-string">"); subHtml.Append(CLOSE_HEAD_TAG); return subHtml.ToString(); } private void GetMetaTags(System.Text.StringBuilder htmlBuilder, string oldHtml) { foreach(string metaTag in _config.MetaTags.Keys) { if(oldHtml.IndexOf(metaTag) == -1) { htmlBuilder.Append("</span>/r/n/t/t<span class="cpp-string">"); htmlBuilder.Append("</span> <span class="cpp-string">" + "</span> htmlBuilder.Append(<span class="cpp-string">"NAME=/"</span><span class="cpp-string">"); htmlBuilder.Append(metaTag); htmlBuilder.Append("</span>/<span class="cpp-string">""</span>); htmlBuilder.Append(<span class="cpp-string">" CONTENT=/"</span><span class="cpp-string">"); htmlBuilder.Append(_config.MetaTags.Get(metaTag)); htmlBuilder.Append("</span>/<span class="cpp-string">"/>"</span>); } } } <span class="cs-keyword">private</span> <span class="cs-keyword">void</span> GetStyleSheetLinks(System.Text.StringBuilder scriptLinks) { <span class="cs-keyword">foreach</span>(<span class="cs-keyword">string</span> key <span class="cs-keyword">in</span> <span class="cs-keyword">this</span>._config.StyleSheets.Keys) { scriptLinks.Append(<span class="cpp-string">"/r/n/t/t "</span> + <span class="cpp-string">" scriptLinks.Append("</span>type=/<span class="cpp-string">"text/css/"</span> <span class="cpp-string">"); scriptLinks.Append("</span>rel=/<span class="cpp-string">"stylesheet/"</span> <span class="cpp-string">"); scriptLinks.Append("</span>href=/<span class="cpp-string">""</span>); scriptLinks.Append(ParseRootPath( <span class="cs-keyword">this</span>._config.StyleSheets.Get(key))); scriptLinks.Append(<span class="cpp-string">"/"</span>); scriptLinks.Append(key); scriptLinks.Append(<span class="cpp-string">"/"</span><span class="cpp-string">"); scriptLinks.Append("</span>/><span class="cpp-string">"); scriptLinks.Append(Environment.NewLine); } } private void GetScriptLinks(System.Text.StringBuilder scriptLinks) { foreach(string key in this._config.Scripts.Keys) { scriptLinks.Append("</span>/r/n/t/t <span class="cpp-string">"); } } #endregion #region Utility Methods private string ParseRootPath(string path) { if(path.IndexOf('~') == 0) { if(System.Web.HttpContext.Current.Request.ApplicationPath == "</span>/<span class="cpp-string">") { path = path.Replace("</span>~<span class="cpp-string">","</span><span class="cpp-string">"); } else path = path.Replace("</span>~<span class="cpp-string">", System.Web.HttpContext.Current.Request.ApplicationPath); return path; } else return path; } private void InitFromConfiguration(string pageName) { this._config = (Configuration.BasePageConfiguration)Cache["</span>BASE_CONFIGURATION_<span class="cpp-string">" + pageName]; if(this._config == null) { Configuration.BasePagesConfiguration baseConfiguration = (Configuration.BasePagesConfiguration) System.Configuration.ConfigurationSettings.GetConfig( "</span><span class="cs-keyword">base</span>.configuration<span class="cpp-string">"); if(baseConfiguration == null) return; //the base configuration was not set //in the current web.config - exit now... //load the current page's configuration and stick it //into cache so it does not have to be reloaded //on subsequent requests this._config = baseConfiguration[pageName]; Cache.Add("</span>BASE_CONFIGURATION_" + pageName, <span class="cs-keyword">this</span>._config,<span class="cs-keyword">null</span>,DateTime.MaxValue, TimeSpan.FromDays(<span class="cs-literal">100</span>), System.Web.Caching.CacheItemPriority.NotRemovable,<span class="cs-keyword">null</span>); } } <span class="cs-preprocessor"> #endregion</span> <span class="cs-preprocessor"> #region Virutal Methods</span> <span class="cs-keyword">protected</span> <span class="cs-keyword">virtual</span> <span class="cs-keyword">void</span> InitializeConfiguration(<span class="cs-keyword">ref</span> ConfigLoadingArgs configParams) {} <span class="cs-comment">/// </span> <span class="cs-comment">/// override this method in our child pages to allow us</span> <span class="cs-comment">/// to set base page state before any rendering takes place</span> <span class="cs-comment">/// in the base page</span> <span class="cs-comment">/// </span> <span class="cs-keyword">protected</span> <span class="cs-keyword">virtual</span> <span class="cs-keyword">void</span> BasePreRender(BaseServerForm baseForm) {} <span class="cs-comment">/// </span> <span class="cs-comment">/// override this method to allow the</span> <span class="cs-comment">/// base page to load the base UI template</span> <span class="cs-comment">/// the base UI template is of type BaseUITemplate</span> <span class="cs-comment">/// BaseUITemplate is of type Usercontrol</span> <span class="cs-comment">/// </span> <span class="cs-keyword">protected</span> <span class="cs-keyword">virtual</span> <span class="cs-keyword">void</span> LoadBaseUITemplate(<span class="cs-keyword">ref</span> BasePageFramework.IBaseTemplate tmplt) {} <span class="cs-comment">/// </span> <span class="cs-comment">/// override in the base page so you can load</span> <span class="cs-comment">/// user controls at the derived base page</span> <span class="cs-comment">/// where you want them to be loaded - this is done</span> <span class="cs-comment">/// so the derived base page can subscribe to events</span> <span class="cs-comment">/// fired by these controls</span> <span class="cs-comment">/// </span> <span class="cs-keyword">protected</span> <span class="cs-keyword">virtual</span> <span class="cs-keyword">void</span> LoadTemplatePanels() {} <span class="cs-comment">/// </span> <span class="cs-comment">/// override this method to initialize the smart</span> <span class="cs-comment">/// querystring with your derived smart querystring instance </span> <span class="cs-comment">/// </span> <span class="cs-comment">/// derived instance of a smart query string base</span> <span class="cs-comment">/// class that Implements the ISmartQueryString interface</span> <span class="cs-keyword">protected</span> <span class="cs-keyword">virtual</span> <span class="cs-keyword">void</span> InitSmartQueryString(<span class="cs-keyword">ref</span> ISmartQueryString isqs) {} <span class="cs-comment">/// </span> <span class="cs-comment">/// override this method to initialized the smart session</span> <span class="cs-comment">/// state with your derived smart session instance</span> <span class="cs-comment">/// </span> <span class="cs-comment">/// derirved smart session object that implements</span> <span class="cs-comment">/// the ISmartSession Interface</span> <span class="cs-keyword">protected</span> <span class="cs-keyword">virtual</span> <span class="cs-keyword">void</span> InitSmartSession(<span class="cs-keyword">ref</span> ISmartSession ises) {} <span class="cs-comment">/// </span> <span class="cs-comment">/// override this method to initialize the smart</span> <span class="cs-comment">/// application state with your derived smart application instance</span> <span class="cs-comment">/// </span> <span class="cs-comment">/// derived smart application object that</span> <span class="cs-comment">/// implements the ISmartApplication interface</span> <span class="cs-keyword">protected</span> <span class="cs-keyword">virtual</span> <span class="cs-keyword">void</span> InitSmartApplication(<span class="cs-keyword">ref</span> ISmartApplication iapp) {} <span class="cs-preprocessor"> #endregion</span> }</pre> <p>Here is how you implement a page that derives from the <code>SuperBasePage</code>:</p> <pre><span class="cs-keyword">public</span> <span class="cs-keyword">class</span> AcmeBase : BasePageFramework.SuperBasePage { <span class="cs-keyword">protected</span> <span class="cs-keyword">override</span> <span class="cs-keyword">void</span> LoadBaseUITemplate(<span class="cs-keyword">ref</span> BasePageFramework.IBaseTemplate tmplt) { tmplt = (IBaseTemplate) LoadControl(<span class="cpp-string">"~/BaseTemplateControl.ascx"</span>); } <span class="cs-keyword">protected</span> <span class="cs-keyword">override</span> <span class="cs-keyword">void</span> InitializeConfiguration(<span class="cs-keyword">ref</span> BasePageFramework.Configuration.ConfigLoadingArgs configParams) { configParams.BasePageID = <span class="cpp-string">"AcmeBase"</span>; } <span class="cs-keyword">protected</span> <span class="cs-keyword">override</span> <span class="cs-keyword">void</span> InitSmartApplication(<span class="cs-keyword">ref</span> BasePageFramework.SmartState.ISmartApplication iapp) { iapp = (ISmartApplication)<span class="cs-keyword">new</span> AcmeAppObject(); } <span class="cs-keyword">protected</span> <span class="cs-keyword">override</span> <span class="cs-keyword">void</span> InitSmartQueryString(<span class="cs-keyword">ref</span> BasePageFramework.SmartState.ISmartQueryString isqs) { isqs = (ISmartQueryString)<span class="cs-keyword">new</span> AcmeSmartQueryString(); } <span class="cs-keyword">protected</span> <span class="cs-keyword">override</span> <span class="cs-keyword">void</span> InitSmartSession(<span class="cs-keyword">ref</span> BasePageFramework.SmartState.ISmartSession ises) { ises = (ISmartSession)<span class="cs-keyword">new</span> AcmeSmartSession(); } }</pre> <p>And this is the derived base template implementation that gets loaded during the virtual <code>LoadBaseUITemplate</code> call:</p> <pre><span class="cs-keyword">public</span> <span class="cs-keyword">class</span> AcmeBaseTemplateMain : System.Web.UI.UserControl, BasePageFramework.IBaseTemplate { <span class="cs-keyword">private</span> PlaceHolder _header = <span class="cs-keyword">new</span> PlaceHolder(); <span class="cs-keyword">private</span> PlaceHolder _leftNavigation = <span class="cs-keyword">new</span> PlaceHolder(); <span class="cs-keyword">private</span> PlaceHolder _contentArea = <span class="cs-keyword">new</span> PlaceHolder(); <span class="cs-keyword">private</span> <span class="cs-keyword">void</span> Page_Load(<span class="cs-keyword">object</span> sender, System.EventArgs e) { <span class="cs-comment">// Put user code to initialize the page here</span> } <span class="cs-preprocessor"> #region IBaseTemplate Members</span> <span class="cs-keyword">public</span> PlaceHolder ContentArea { <span class="cs-keyword">get</span> { <span class="cs-keyword">return</span> _contentArea; <span class="cs-comment">//The IBaseTemplate Interface's ContentArea method </span> <span class="cs-comment">//is used by the SuperBasePage to handle </span> <span class="cs-comment">//content placement from the derived page</span> } } <span class="cs-keyword">public</span> PlaceHolder Header { <span class="cs-keyword">get</span>{<span class="cs-keyword">return</span> _header;} <span class="cs-comment">//PLACEHOLDER THAT CONTAINS OUR HEADER'S CONTENT</span> } <span class="cs-keyword">public</span> PlaceHolder LeftNav { <span class="cs-keyword">get</span>{<span class="cs-keyword">return</span> _leftNavigation;} <span class="cs-comment">//PLACEHOLDER THAT CONTAINS OUR LEFT NAV BAR</span> } <span class="cs-preprocessor"> #endregion</span> }</pre> <p>You can see that I am using a combination of overriding the <code>AddParsedSubObject()</code> and the <code>AddChildControls()</code> virtual methods. This is because we only need to use the <code>AddParsedSubObject()</code> method to do one thing. Intercept our HTML header and HTML form before it gets added to our page. I got this idea from Micheal Earls (a fellow Magenicon from Atlanta). Check out his blog here. I have seen this method overridden in server controls for child control tags but not in a page class like this. I thought it was a very clever use of the method and it solves the problem of having to remove the outer HTML from around our content area. Now that we have the outer HTML intact it also gives us the opportunity to override the Base page configuration at the page level thus imitating the <i>web.config</i> settings/page directive pattern that currently exists in ASP.NET.</p> <p>For those of you unfamiliar with this method, it gets fired whenever a handler encounters a child element. In the case of the <code>System.Web.Page</code> class, it gets fired a total of three times.</p> <ol> <li>Once when it encounters the tag. </li> <li>Once when it encounters the tag. </li> <li>And one more time when it encounters the tag. </li> </ol> <p>As you may have already guessed, we only really care about the first two, when it is fired for the HTML tag, that is when we get our custom configuration settings and place them into the header. This part of the handler needs to really scream so I struggled for awhile on what would be the best way. I have used <code>HtmlWriter</code>s in the past but I thought for this it was too much overhead since we are already using one in the render call, plus I am forced to parse all the HTML in order to make that approach effective (so clearly, it is not an option here).</p> <p>After some experimentation I decided to go with <code>StringBuilder</code>s since they are faster than vanilla string concatenation (in fact the performance of the <code>StringBuilder</code> is comparable to using the old <code>memcpy()</code> call in C). To truly take advantage of the <code>StringBuilder</code>’s performance you need to estimate how much space you will need ahead of time. If you don’t the <code>StringBuilder</code> will be moving a lot of character memory around when it has to resize itself internally to make more room. I use a combination of the default HTML content along with what is in the <i>web.config</i> to calculate a good initial size for my <code>StringBuilder</code>’s buffer. The reason this is so important is because when the <code>StringBuilder</code> reaches its limit during an <code>append()</code>, it creates a new buffer twice the size of the old one and copies all the character data over to the new buffer (then destroys the old buffer). All this movement of character data negates the performance gains of using a <code>StringBuilder</code> (although it is still probably faster than plain old string concatenation operators). Regardless, it’s better to be safe than sorry IMHO.</p> <p>We are doing some initialization in the <code>CreateChildControls</code> override as well. We do this to ensure that these methods are only called once when the request gets handled. This is done by calling <code>EnsureChildControls()</code> from our <code>init()</code> call. This call “ensures” that our child controls get created (in this case we are initializing the <code>SmartQueryString</code> and <code>SmartSessionState</code>). Since they are not critical to using the Base page and since I am trying to keep this short, I will go into more detail on these two classes in the final part.</p> <p>The virtual methods in the <code>SuperBasePage</code> are to be overridden in our derived <code>SuperBasePage</code> class. Using these virtual methods allows us to define how and what our Base page loads when it is requested.</p> <p>Here is what each method does…</p> <ul> <li><code><span class="cs-keyword">protected</span> <span class="cs-keyword">virtual</span> <span class="cs-keyword">void</span> InitializeConfiguration(<span class="cs-keyword">ref</span> ConfigLoadingArgs configParams);</code> <p>Override this method so we can tell the Base page what page configuration to use. (Remember that we have more than one page element in our config section? This is where we specify what section to use.) In this example, the Base page name attribute we want from our configuration is “<code>AcmeBase</code>”. We are passing the <code>configParams</code> argument by reference so we can set it in our override (in the derived base page).</p><p>Here is an example of how to implement it.</p><pre><span class="cs-keyword">protected</span> <span class="cs-keyword">override</span> <span class="cs-keyword">void</span> InitializeConfiguration(<span class="cs-keyword">ref</span> BasePageFramework.Configuration.ConfigLoadingArgs configParams) { configParams.BasePageID = <span class="cpp-string">"AcmeBase"</span>; }</pre><p>This in turn will tell our Super Base page to load settings from the following page config section…</p><pre><page name="AcmeBase" defaultTitle="Acme Widgets"> <body> <attribute name="topmargin" value="0"/> <attribute name="leftmargin" value="0"/> <attribute name="rightmargin" value="0"/> <attribute name="bottommargin" value="0"/> <attribute name="bgcolor" value="#FFFF00"/> </body> <metatags> <meta name="AcmeMeta" Content="dogs,cats,fish, gerbils,pets,friends,mantees"/> </metatags> <links> <css file="acmestyles.css" path="~/Content/styles"/> <script file="acmescriptlib.js" path="~/Content/scripts"> </links> </page></pre><p>The argument is passed by reference so we can set the Base page name from our derived Base page class. Please note that if the configuration element does not exist, I will throw you an exception (as you can see in the <code>SuperBasePage</code> code). You can also see that I am caching the settings. I do this for two reasons:</p> <ol> <li>If I want to use the same config for more than one page – the configuration will only be created in memory once and shared with all pages that use it. </li> <li>We do not want to parse the configuration on every request as this will cause a serious performance hit. </li> </ol><p>Here is the <code>ConfigLoadingArgs</code> class that is getting passed to our derived page from the <code>SuperBasePage</code> through its virtual method:</p><pre><span class="cs-keyword">public</span> <span class="cs-keyword">class</span> ConfigLoadingArgs { <span class="cs-keyword">private</span> <span class="cs-keyword">string</span> _basePageID = <span class="cs-keyword">string</span>.Empty; <span class="cs-keyword">internal</span> ConfigLoadingArgs() {} <span class="cs-keyword">public</span> <span class="cs-keyword">string</span> BasePageID { <span class="cs-keyword">get</span>{<span class="cs-keyword">return</span> _basePageID;} <span class="cs-keyword">set</span>{_basePageID = value;} } }</pre></li> <li><code><span class="cs-keyword">protected</span> <span class="cs-keyword">virtual</span> <span class="cs-keyword">void</span> BasePreRender(BaseServerForm baseForm)</code> <p>This method gets called in our <code>CreateChildControls</code> call before we load any templates in to our Base UI. I have never needed to use this yet myself but I thought it may be necessary for someone to access the <code>BaseServerForm</code> for this page before it loads any controls. This is where you will do it.</p></li> <li><code><span class="cs-keyword">protected</span> <span class="cs-keyword">virtual</span> <span class="cs-keyword">void</span> LoadBaseUITemplate(<span class="cs-keyword">ref</span> BasePageFramework.IBaseTemplate tmplt)</code> <p>This is where we pull in our main user control (that implements the <code>IBaseTemplate</code> interface) that will provide us with a layout for all the pages in our site. Internally, when the <code>BaseServerForm</code> is loaded and initialized – it will use the <code>IBaseTemplate</code> interface to move the content to the appropriate area.</p><p>Here is how I use it in my derived Base page class – the beauty here is that we are not required to load every single control into all the areas of the main template, you can have some static and some dynamically loaded (in the <code>LoadTemplatePanels</code> call, you will see how we dynamically load controls which we usually do when we want our derived base page to subscribe to a given control's events).</p><pre><span class="cs-keyword">protected</span> <span class="cs-keyword">override</span> <span class="cs-keyword">void</span> LoadBaseUITemplate(<span class="cs-keyword">ref</span> BasePageFramework.IBaseTemplate tmplt) { tmplt = (IBaseTemplate)LoadControl(<span class="cpp-string">"~/BaseTemplateControl.ascx"</span>); }</pre></li> <li><code><span class="cs-keyword">protected</span> <span class="cs-keyword">virtual</span> <span class="cs-keyword">void</span> LoadTemplatePanels()</code> <p>This override allows us to dynamically load controls into the areas of our Base template after the Base template UI and form are loaded and initialized. The reason you may need to do this is so you can attach events and subscribe to them in your derived Base page class (like navigation postbacks, logout requests, etc…). Remember I told you earlier that I was going to let you in as to why I was exposing all the placeholders in my <code>BaseTemplate</code> user control? You can see why in the following snippet of code. I can get to those place holders in my derived Base page. There is a catch however, you need to downcast the initialized <code>IBaseTemplate</code> to whatever class your <code>MainTemplate</code> user control type is within this override, before you can get to the placeholder properties.</p><p>Here is how I use it (I am including an event example so you can see what I want my Base page to do when the event gets fired)…</p><pre><span class="cs-keyword">protected</span> <span class="cs-keyword">override</span> <span class="cs-keyword">void</span> LoadTemplatePanels() { <span class="cs-keyword">this</span>.BaseForm.BaseTemplate.Header.Controls.Add( LoadControl(<span class="cpp-string">"~/BaseControls/AcmeHeader.ascx"</span>)); _leftNavCtl = (LeftNav)LoadControl(<span class="cpp-string">"~/BaseControls/LeftNav.ascx"</span>); <span class="cs-keyword">this</span>.BaseForm.BaseTemplate.LeftNav.Controls.Add(_leftNavCtl ); _leftNavCtl.OnNavEvent += <span class="cs-keyword">new</span> NavEventHandler(OnNavigationEvent); } <span class="cs-keyword">private</span> <span class="cs-keyword">void</span> OnNavigationEvent(<span class="cs-keyword">object</span> sender,NavEventArg e) { <span class="cs-keyword">this</span>.SmartQueryString.SmartRedirect(e.NavURL); }</pre></li> </ul> <p>These are just examples. I plan to release a full project with examples on how to do everything, at a future date.</p> <p>These last two involve the <code>SmartQueryString</code> and <code>SmartSession</code> interfaces. The smart handler interfaces give us the ability to strongly type our <code>QueryString</code>, <code>Session</code> and <code>Application</code> objects. I will go into more detail on the next post on what these methods are used for…</p> <ul class="method"> <li><code><span class="cs-keyword">protected</span> <span class="cs-keyword">virtual</span> <span class="cs-keyword">void</span> InitSmartQueryString(<span class="cs-keyword">ref</span> ISmartQueryString isqs)</code> </li> <li><code><span class="cs-keyword">protected</span> <span class="cs-keyword">virtual</span> <span class="cs-keyword">void</span> InitSmartSession(<span class="cs-keyword">ref</span> ISmartSession ises)</code> </li> <li><code><span class="cs-keyword">protected</span> <span class="cs-keyword">virtual</span> <span class="cs-keyword">void</span> InitSmartApplication(<span class="cs-keyword">ref</span> ISmartApplication iapp)</code> </li> </ul> <h2>Other methods in the Base page base…</h2> <ul class="method"> <li><code><span class="cs-keyword">private</span> <span class="cs-keyword">string</span> ParseRootPath(<span class="cs-keyword">string</span> path)</code> <p>This method ensures that we always know where in the site our controls/resources/etc… are located in relation to the derived page. It uses the standard ASP.NET recognition of the tilde “~” as the delimiter for our application root. This is important because we may be running our application out of a virtual directory (in the case of running it from the root of a website, we could have just used the standard forward slash “/” in front of our links to specify the site’s root). Don’t forget that this page can be used by all pages of your site in any subdirectory, which also means that since your pages are in different directories / subdirectories, you need this so your pages can always find the user controls and other site resources, etc....</p></li> <li><code><span class="cs-keyword">private</span> <span class="cs-keyword">void</span> InitFromConfiguration(<span class="cs-keyword">string</span> pageName)</code> <p>This is where we get our custom configuration settings. Remember that one of the features of the framework is that the individual pages can override the settings you put in the <i>web.config</i>. That way if you want the same layout (but a different backcolor, script, metatag, etc…) you can do it without having to hard code it, just do it the way any web designer would do it, put it in the hypertext where it belongs. If you don’t override it, then the page will use the settings from the <i>web.config</i>. This follows the same “machine/web/page” pattern used in all the directives of ASP.NET.</p></li> </ul> <p>Well, that was a lot to say (and for you to read). I tried to keep it short since this is just a blog post. So if you have any questions just ask and I will be happy to answer. In the last part of this article, I will talk about the Smart Handler objects (<code>SmartSession</code>, <code>SmartQueryString</code>, <code>SmartApplication</code>) and how you can create your own base handlers to persist values differently. To explain what they are for, they allow us to manage our querystring, etc… from a within our Base page (like the response and request objects already do – these are strongly typed and easy to use). They have made my life infinitely easier.</p> <h2>Part IV - Implementing the Smart Session Objects</h2> <p>In this final part (for now anyway, until someone gives me some better ideas or I wake up in the middle of the night with one of my own), I am going to describe how to implement the Smart State Objects that we can get data from via the master page. One of the things I really don’t like to do is having to hardcode strings to find stuff in a generic collection object and then rely on that object being of a specific type before I can actually use it. When I am working on the project independently it is not as much of a problem, but when it grows to more than a couple of developers, it gets tough to keep track of the keys (unless of course you step through the entire application with trace turned on so you can monitor additions and removals from our state objects).</p> <p>This gets even worse when dealing with querystring data. You can add and remove things from the query string anywhere and it does not have to be consistent, so when you redirect to another page on the web app, you are assuming that the next page is always going to have access to the query string elements you are going to need and worse, that the values that they represent are not going to change in context. My solution to this is to wrap these objects in my own smart session classes. We had a monster problem synching up the query string that we were using at an E-commerce project once, and the minute the scope shifted and the client stated that they wanted another feature (and another querystring because this site had to do all its state maintenance through the query string), we had to go through every page in our purchasing and payment process, etc… to make sure this element was added when it was needed (and worse – they were using string concatenation operators to do it on every single redirect in the site). Yuck!!!</p> <p>So I took a little time and wisely spent some time coming up with a better way to handle this problem, the solution is the <code>ISmartQueryString</code>, <code>ISmartSession</code> and <code>ISmartApplication</code> interfaces. Here is an example of the interfaces followed by what they allow us to do…</p> <pre><span class="cs-keyword">public</span> <span class="cs-keyword">interface</span> ISmartSession { <span class="cs-keyword">void</span> SetSessionState(System.Web.SessionState.HttpSessionState ses); <span class="cs-keyword">void</span> FlushSessionState(); <span class="cs-keyword">void</span> AbandonSession(); <span class="cs-keyword">void</span> PersistToSession(); } <span class="cs-keyword">public</span> <span class="cs-keyword">interface</span> ISmartQueryString { <span class="cs-keyword">void</span> SetQueryStringInfo(System.Web.UI.Page webPage); <span class="cs-keyword">void</span> SmartRedirect(<span class="cs-keyword">string</span> url); } <span class="cs-keyword">public</span> <span class="cs-keyword">interface</span> ISmartApplication { <span class="cs-keyword">void</span> FlushAppState(); <span class="cs-keyword">void</span> PersistToAppState(); <span class="cs-keyword">void</span> SetApplicationState(System.Web.HttpApplicationState state); }</pre> <p><b><code>ISmartQueryStirng</code></b>: Allows us to encapsulate the query string in one spot in our code – we are always going to be assured of an element's existence (with default values set) so we do not need to write the code to check this in every single page. We will implement this interface in our <code>SmartQueryStringBase</code> class (more on that in a bit).</p> <p>Here are the methods that need to be implemented in the <code>ISmartQueryString</code>:</p> <ul class="method"> <li><code><span class="cs-keyword">void</span> SetQueryStringInfo(System.Web.UI.Page webPage);</code> <p>This is where we pass our HTTP handler (the page object in the case of ASP.NET) to our smart query string base. We need to pass the whole thing because we are going to be using several items out of not only the request object but also the response object as you will see in a bit.</p></li> <li><code><span class="cs-keyword">void</span> SmartRedirect(<span class="cs-keyword">string</span> url);</code> <p>This is the magic call that keeps our querystring alive in the system. Yes, your developers can go ahead and just use the <code>Response</code> call directly and break it but that is easily remedied if you find it somewhere in the code. (Try using a <code>Find</code> on <code>Response</code>. And you will find it in no time!) Another thing you could do is use FXCop to keep it from happening if you need to automate the restriction. Then you can do whatever you do to the misguided developer and keep in on focus with the rest of the team.</p></li> </ul> <p>Now a framework wouldn’t be complete without an out of the box implementation of this interface so I am providing one. In this interface I am using reflection to get the values out of my <code>SmartQueryString</code> object (I am going to call it <code>AcmeSmartQueryString()</code> for lack of a better name). You can see in the following code how reflection takes the property values of our smart querystring and moves the value to our querystring. I am also putting a prefix on this: “<code>sqs</code>” for “Smart Query String”. This tells our smart query string class that there is a query string present and it can begin parsing it out back into our <code>AcmeSmartQueryString()</code> object when the MasterPage is initialized during a request. Here is the code…</p> <pre>[Serializable()] <span class="cs-keyword">public</span> <span class="cs-keyword">abstract</span> <span class="cs-keyword">class</span> SmartQueryStringBase : ISmartQueryString { [field: NonSerialized()] <span class="cs-keyword">private</span> System.Web.UI.Page _page = <span class="cs-keyword">null</span>; <span class="cs-keyword">public</span> <span class="cs-keyword">void</span> SetQueryStringInfo(System.Web.UI.Page webPage) { _page = webPage; ExtractQueryStringInfo(); } <span class="cs-keyword">public</span> <span class="cs-keyword">void</span> SmartRedirect(<span class="cs-keyword">string</span> url) { <span class="cs-comment">//build a querystring from the internal elements </span> <span class="cs-comment">//of this class and redirect the user</span> <span class="cs-keyword">string</span> qs = GenerateQueryString(); <span class="cs-keyword">if</span>(qs != <span class="cs-keyword">string</span>.Empty) _page.Response.Redirect(ParseRootPath(url) + <span class="cpp-string">"?sqs=true&"</span> + qs); <span class="cs-keyword">else</span> _page.Response.Redirect(ParseRootPath(url)); } <span class="cs-comment">//use reflection to take our objects field values </span> <span class="cs-comment">//and format it into a querystring</span> <span class="cs-keyword">private</span> <span class="cs-keyword">string</span> GenerateQueryString() { PropertyInfo [] props = <span class="cs-keyword">this</span>.GetType().GetProperties(); StringBuilder sb = <span class="cs-keyword">new</span> StringBuilder(); <span class="cs-keyword">foreach</span>(PropertyInfo prop <span class="cs-keyword">in</span> props) { BasePageFramework.Attributes.SmartQueryStringKeyAttribute [] attb = (BasePageFramework.Attributes.SmartQueryStringKeyAttribute []) prop.GetCustomAttributes(<span class="cs-keyword">typeof</span>( BasePageFramework.Attributes.SmartQueryStringKeyAttribute), <span class="cs-keyword">true</span>); <span class="cs-comment">//use the name if the attribute was omitted from the property</span> <span class="cs-keyword">if</span>(attb.Length == <span class="cs-literal">0</span>) sb.Append(prop.Name + <span class="cpp-string">"="</span> + prop.GetValue(<span class="cs-keyword">this</span>, <span class="cs-keyword">null</span>).ToString() + <span class="cpp-string">"&"</span>); <span class="cs-keyword">else</span> sb.Append(attb[<span class="cs-literal">0</span>].KeyName + <span class="cpp-string">"="</span> + prop.GetValue(<span class="cs-keyword">this</span>,<span class="cs-keyword">null</span>).ToString() + <span class="cpp-string">"&"</span>); } <span class="cs-keyword">return</span> sb.ToString(); } <span class="cs-keyword">public</span> <span class="cs-keyword">override</span> <span class="cs-keyword">string</span> ToString() { <span class="cs-keyword">return</span> <span class="cpp-string">"?sqs=true&"</span> + GenerateQueryString(); } <span class="cs-keyword">private</span> <span class="cs-keyword">string</span> ParseRootPath(<span class="cs-keyword">string</span> path) { <span class="cs-keyword">if</span>(path.IndexOf('~') == <span class="cs-literal">0</span>) { <span class="cs-keyword">if</span>(System.Web.HttpContext.Current.Request.ApplicationPath == <span class="cpp-string">"/"</span>) { path = path.Replace(<span class="cpp-string">"~"</span>,<span class="cpp-string">""</span>); } <span class="cs-keyword">else</span> path = path.Replace(<span class="cpp-string">"~"</span>, System.Web.HttpContext.Current.Request.ApplicationPath); <span class="cs-keyword">return</span> path; } <span class="cs-keyword">else</span> <span class="cs-keyword">return</span> path; } <span class="cs-keyword">private</span> <span class="cs-keyword">void</span> ExtractQueryStringInfo() { <span class="cs-keyword">string</span> sqsElement = _page.Request.QueryString[<span class="cpp-string">"sqs"</span>]; <span class="cs-keyword">if</span>(sqsElement != <span class="cs-keyword">null</span> && sqsElement != <span class="cs-keyword">string</span>.Empty) { PropertyInfo [] props = <span class="cs-keyword">this</span>.GetType().GetProperties(); <span class="cs-keyword">foreach</span>(PropertyInfo prop <span class="cs-keyword">in</span> props) { BasePageFramework.Attributes.SmartQueryStringKeyAttribute [] attb = (BasePageFramework.Attributes.SmartQueryStringKeyAttribute []) prop.GetCustomAttributes(<span class="cs-keyword">typeof</span>( BasePageFramework.Attributes.SmartQueryStringKeyAttribute),<span class="cs-keyword">true</span>); <span class="cs-keyword">if</span>(attb.Length == <span class="cs-literal">0</span>) prop.SetValue(<span class="cs-keyword">this</span>,GetFieldValue(prop.Name),<span class="cs-keyword">null</span>); <span class="cs-keyword">else</span> prop.SetValue(<span class="cs-keyword">this</span>,GetFieldValue(attb[<span class="cs-literal">0</span>].KeyName),<span class="cs-keyword">null</span>); } } } <span class="cs-keyword">private</span> <span class="cs-keyword">object</span> GetFieldValue(<span class="cs-keyword">string</span> elementName) { <span class="cs-keyword">string</span> retval = _page.Request.QueryString.Get(elementName); <span class="cs-keyword">if</span>(retval != <span class="cs-keyword">null</span>) <span class="cs-keyword">return</span> retval; <span class="cs-keyword">else</span> <span class="cs-keyword">return</span> <span class="cs-keyword">string</span>.Empty; } }</pre> <p>Finally, if you look, you can see what the <code>SmartRedirect</code> does. It’s nice because you only need supply the smart redirect with the URL where you are going and the smart query string does the rest of the work for you! Not too shabby!</p> <p>Now if you are looking closely you will also see that I am using an attribute to generate the key name for our query string. This is the <code>SmartQueryStringKeyAttribute()</code>. We will apply this attribute to our <code>AcmeSmartQueryString</code> object’s properties so we can keep the key values short and sweet in our query string's output.</p> <p>And here is the attribute class we are using to create our key value output…</p> <pre><span class="cs-keyword">public</span> <span class="cs-keyword">class</span> SmartQueryStringKeyAttribute : System.Attribute { <span class="cs-keyword">private</span> <span class="cs-keyword">string</span> _queryStringKey = <span class="cs-keyword">string</span>.Empty; <span class="cs-keyword">public</span> SmartQueryStringKeyAttribute(<span class="cs-keyword">string</span> queryStringKey) { _queryStringKey = queryStringKey; } <span class="cs-keyword">public</span> <span class="cs-keyword">string</span> KeyName { <span class="cs-keyword">get</span>{<span class="cs-keyword">return</span> _queryStringKey;} } }</pre> <p>Finally – here is the <code>AcmeSmartQueryString</code> class (our derived smart query string object that holds our smart query string's values for the app):</p> <pre><span class="cs-keyword">public</span> <span class="cs-keyword">class</span> AcmeSmartQueryString : BasePageFramework.SmartState.SmartQueryStringBase { <span class="cs-keyword">private</span> <span class="cs-keyword">string</span> _pgNum = <span class="cs-keyword">string</span>.Empty; <span class="cs-keyword">private</span> <span class="cs-keyword">string</span> _tabIdx = <span class="cs-keyword">string</span>.Empty; <span class="cs-keyword">private</span> <span class="cs-keyword">string</span> _userName = <span class="cs-keyword">string</span>.Empty; <span class="cs-keyword">public</span> AcmeSmartQueryString() {} [BasePageFramework.Attributes.SmartQueryStringKey(<span class="cpp-string">"pn"</span>)] <span class="cs-keyword">public</span> <span class="cs-keyword">string</span> PageNumber { <span class="cs-keyword">get</span>{<span class="cs-keyword">return</span> _pgNum;} <span class="cs-keyword">set</span>{_pgNum = value;} } [BasePageFramework.Attributes.SmartQueryStringKey(<span class="cpp-string">"ti"</span>)] <span class="cs-keyword">public</span> <span class="cs-keyword">string</span> TabIndex { <span class="cs-keyword">get</span>{<span class="cs-keyword">return</span> _tabIdx;} <span class="cs-keyword">set</span>{_tabIdx = value;} } [BasePageFramework.Attributes.SmartQueryStringKey(<span class="cpp-string">"un"</span>)] <span class="cs-keyword">public</span> <span class="cs-keyword">string</span> UserName { <span class="cs-keyword">get</span>{<span class="cs-keyword">return</span> _userName;} <span class="cs-keyword">set</span>{_userName = value;} } }</pre> <p>You can see that this class does not interact with its base members, this is the beauty of using the interface. You do not need to worry about what is happening to translate the query string to and from this object because it all happens behind the scenes. You are now free to interact with this object as you need just like it’s another instance in your code. I left out one of the attributes so you can see what happens on the receiving end when the next page request is filled. You will see the whole name for the property. It just has state and that’s it! That’s the beauty of it, our developers using this framework do not need to know what is happening under the hood, they just have to interact with this instance and they are good to go… Keep in mind that the smart query string although maps properties to our smart query string, you can only use strings with it (hence the name). I am looking into ways to allow you to add other types to the query string (enumerations, other value types etc…). I will leave that matter as the subject of a future post.</p> <p>Here is our Acme Master Page that not only initializes the other Master Page components but also loads our <code>AcmeSmartQueryString</code>:</p> <pre><span class="cs-keyword">public</span> <span class="cs-keyword">class</span> AcmeBasePage : BasePageFramework.SuperBasePage { <span class="cs-keyword">private</span> AcmeControls.LeftNav _leftNav = <span class="cs-keyword">null</span>; <span class="cs-keyword">protected</span> <span class="cs-keyword">override</span> <span class="cs-keyword">void</span> LoadBaseUITemplate(<span class="cs-keyword">ref</span> BasePageFramework.IBaseTemplate tmplt) { tmplt = (BasePageFramework.IBaseTemplate) LoadControl(<span class="cpp-string">"~/Base/AcmeBaseTemplate.ascx"</span>); } <span class="cs-keyword">protected</span> <span class="cs-keyword">override</span> <span class="cs-keyword">void</span> LoadTemplatePanels() { _leftNav = (AcmeControls.LeftNav) LoadControl(<span class="cpp-string">"~/AcmeControls/LeftNav.ascx"</span>); ((AcmeBaseTemplate) <span class="cs-keyword">this</span>.MainUITemplate).LeftNavigation.Controls.Add(_leftNav); _leftNav.OnNavClick += <span class="cs-keyword">new</span> AcmeWidgets.AcmeControls.LeftNavEvent(_leftNav_OnNavClick); } <span class="cs-keyword">protected</span> <span class="cs-keyword">override</span> <span class="cs-keyword">void</span> InitializeConfiguration(<span class="cs-keyword">ref</span> BasePageFramework.Configuration.ConfigLoadingArgs configParams) { configParams.BasePageID = <span class="cpp-string">"AcmeBase"</span>; } <span class="cs-keyword">protected</span> <span class="cs-keyword">override</span> <span class="cs-keyword">void</span> InitSmartQueryString(<span class="cs-keyword">ref</span> BasePageFramework.SmartState.ISmartQueryString isqs) { isqs = (BasePageFramework.SmartState.ISmartQueryString) <span class="cs-keyword">new</span> AcmeSmartState.AcmeSmartQueryString(); } <span class="cs-keyword">protected</span> <span class="cs-keyword">override</span> <span class="cs-keyword">void</span> InitSmartSession(<span class="cs-keyword">ref</span> BasePageFramework.SmartState.ISmartSession ises) { ises = (BasePageFramework.SmartState.ISmartSession) <span class="cs-keyword">new</span> AcmeSmartState.AcmeSmartSession(); } <span class="cs-keyword">private</span> <span class="cs-keyword">void</span> _leftNav_OnNavClick(<span class="cs-keyword">object</span> sender, AcmeWidgets.AcmeControls.LeftNavEventArg e) { <span class="cs-keyword">switch</span>(e.PageNumber) { <span class="cs-keyword">case</span> <span class="cpp-string">"1"</span>: <span class="cs-keyword">this</span>.SmartQueryString.SmartRedirect(<span class="cpp-string">"Default.aspx"</span>); <span class="cs-keyword">break</span>; <span class="cs-keyword">case</span> <span class="cpp-string">"2"</span>: <span class="cs-keyword">this</span>.SmartQueryString.SmartRedirect(<span class="cpp-string">"PageTwo.aspx"</span>); <span class="cs-keyword">break</span>; <span class="cs-keyword">case</span> <span class="cpp-string">"3"</span>: <span class="cs-keyword">this</span>.SmartQueryString.SmartRedirect(<span class="cpp-string">"PageThree.aspx"</span>); <span class="cs-keyword">break</span>; <span class="cs-keyword">case</span> <span class="cpp-string">"4"</span>: <span class="cs-keyword">this</span>.SmartQueryString.SmartRedirect(<span class="cpp-string">"PageFour.aspx"</span>); <span class="cs-keyword">break</span>; <span class="cs-keyword">default</span>: <span class="cs-keyword">this</span>.SmartQueryString.SmartRedirect(<span class="cpp-string">"Default.aspx"</span>); <span class="cs-keyword">break</span>; } } }</pre> <p>You can see in our event handler in the above page that we are using the <code>SmartQueryString</code> of the current instance (initialized in our base page when it gets requested) to do the redirection and keep our string elements intact. This not only makes it easier to manage the querystring, it also centralizes everything that happens in the querystring in one place making maintenance infinitely easier.</p> <p>On a side note, so I know what some of you are saying… But I <b>hate</b> using reflection!! Why not use a formatter or typeconverter instead??!! To answer that question, you can write your own. I created interfaces for these objects so you can create your own <code>SmartQueryStringBase</code> class (along with the other smart state objects) – the master page base does not care – all it needs to keep a reference to are these interfaces, so write your own if you must.</p> <p>Now for the other smart state objects, things are not as automatic because we do not have the “Smart Redirect” to pass the data along to our code so it can be persisted. Therefore we need to tell the other SmartState Objects to persist themselves whenever we change something in them. These interfaces are fairly straightforward minus the fact that we have to set the state somehow. That is where “<code>SetApplicationState</code>” and “<code>SetSessionState</code>” come in. Pass these calls the appropriate state object and away you go!</p> <p>Here is our <code>SmartSessionBase</code> class that comes out of the box:</p> <pre>[Serializable] <span class="cs-keyword">public</span> <span class="cs-keyword">class</span> SmartSessionBase : ISmartSession { <span class="cs-comment">// Fields</span> [field: NonSerialized()] <span class="cs-keyword">private</span> HttpSessionState _session = <span class="cs-keyword">null</span>; <span class="cs-keyword">private</span> <span class="cs-keyword">void</span> ExtractSessionStateRefs() { <span class="cs-keyword">foreach</span>(PropertyInfo inf <span class="cs-keyword">in</span> <span class="cs-keyword">this</span>.GetType().GetProperties()) inf.SetValue(<span class="cs-keyword">this</span>,<span class="cs-keyword">this</span>._session[inf.Name],<span class="cs-keyword">null</span>); } <span class="cs-keyword">void</span> ISmartSession.AbandonSession() { <span class="cs-keyword">this</span>._session.Abandon(); } <span class="cs-keyword">void</span> ISmartSession.FlushSessionState() { <span class="cs-keyword">this</span>._session.Clear(); } <span class="cs-keyword">void</span> ISmartSession.PersistToSession() { <span class="cs-keyword">foreach</span>(PropertyInfo inf <span class="cs-keyword">in</span> <span class="cs-keyword">this</span>.GetType().GetProperties()) { <span class="cs-keyword">this</span>._session[inf.Name] = inf.GetValue(<span class="cs-keyword">this</span>,<span class="cs-keyword">null</span>); } } <span class="cs-keyword">void</span> ISmartSession.SetSessionState(HttpSessionState ses) { <span class="cs-keyword">this</span>._session = ses; <span class="cs-keyword">this</span>.ExtractSessionStateRefs(); } }</pre> <p>Here is the <code>AcmeSmartSessionBase</code> implementation (I included the <code>Person</code> object so you can see the class we are keeping in session state:</p> <pre><span class="cs-keyword">public</span> <span class="cs-keyword">class</span> AcmeSmartSession : BasePageFramework.SmartState.SmartSessionBase { <span class="cs-keyword">private</span> Person _person = <span class="cs-keyword">null</span>; <span class="cs-keyword">public</span> Person SelectedPerson { <span class="cs-keyword">get</span>{<span class="cs-keyword">return</span> _person;} <span class="cs-keyword">set</span>{_person = value;} } } [Serializable()] <span class="cs-keyword">public</span> <span class="cs-keyword">class</span> Person { <span class="cs-keyword">string</span> _name = <span class="cs-keyword">string</span>.Empty; <span class="cs-keyword">int</span> _age = <span class="cs-literal">0</span>; <span class="cs-keyword">int</span> _weight = <span class="cs-literal">0</span>; <span class="cs-keyword">public</span> <span class="cs-keyword">string</span> Name { <span class="cs-keyword">get</span>{<span class="cs-keyword">return</span> _name;} <span class="cs-keyword">set</span>{_name = value;} } <span class="cs-keyword">public</span> <span class="cs-keyword">int</span> Age { <span class="cs-keyword">get</span>{<span class="cs-keyword">return</span> _age;} <span class="cs-keyword">set</span>{_age = value;} } <span class="cs-keyword">public</span> <span class="cs-keyword">int</span> Weight { <span class="cs-keyword">get</span>{<span class="cs-keyword">return</span> _weight;} <span class="cs-keyword">set</span>{_weight = value;} } }</pre> <p>Using the application state is similar except that we lock the instance before we mess with it. Here is the code for our default <code>SmartApplicationStateBase</code> (not too much different from the <code>SmartSessionBase</code> aside from the thread sync stuff):</p> <pre><span class="cs-keyword">public</span> <span class="cs-keyword">class</span> SmartApplicationBase : ISmartApplication { [field: NonSerialized()] <span class="cs-keyword">private</span> HttpApplicationState _appState = <span class="cs-keyword">null</span>; <span class="cs-preprocessor"> #region ISmartApplication Members</span> <span class="cs-keyword">public</span> <span class="cs-keyword">void</span> FlushAppState() { CheckInit(); _appState.Clear(); } <span class="cs-keyword">public</span> <span class="cs-keyword">void</span> PersistToAppState() { CheckInit(); _appState.Lock(); <span class="cs-comment">//update the derived smartapplication object </span> <span class="cs-comment">//to the application state...</span> <span class="cs-keyword">foreach</span>(PropertyInfo inf <span class="cs-keyword">in</span> <span class="cs-keyword">this</span>.GetType().GetProperties()) <span class="cs-keyword">this</span>._appState[inf.Name] = inf.GetValue(<span class="cs-keyword">this</span>,<span class="cs-keyword">null</span>); _appState.UnLock(); } <span class="cs-keyword">public</span> <span class="cs-keyword">void</span> SetApplicationState(System.Web.HttpApplicationState state) { _appState = state; <span class="cs-comment">//extract the values out of application state </span> <span class="cs-comment">//so our smart application object </span> <span class="cs-comment">//has everything it needs to be referenced in the page</span> _appState.Lock(); <span class="cs-keyword">foreach</span>(PropertyInfo inf <span class="cs-keyword">in</span> <span class="cs-keyword">this</span>.GetType().GetProperties()) inf.SetValue(<span class="cs-keyword">this</span>,<span class="cs-keyword">this</span>._appState[inf.Name],<span class="cs-keyword">null</span>); _appState.UnLock(); } <span class="cs-keyword">private</span> <span class="cs-keyword">void</span> CheckInit() { <span class="cs-keyword">if</span>(_appState == <span class="cs-keyword">null</span>) <span class="cs-keyword">throw</span> <span class="cs-keyword">new</span> InvalidOperationException(<span class="cpp-string">"The SmartApplicationState"</span> + <span class="cpp-string">" must be initialized before it is accessed"</span>); } <span class="cs-preprocessor"> #endregion</span> }</pre> <p>Finally here is an example of how to use these objects (remember our master page already set these up for us so they are all ready to go when we need them):</p> <pre><span class="cs-keyword">private</span> <span class="cs-keyword">void</span> Button1_Click(<span class="cs-keyword">object</span> sender, System.EventArgs e) { <span class="cs-comment">//create an object</span> Classes.AcmeClass cls = <span class="cs-keyword">new</span> Classes.AcmeClass(<span class="cpp-string">"Chase"</span>,<span class="cs-literal">30</span>); <span class="cs-comment">//set it into our smartsession instance</span> ((Master.AcmeSmartSession)<span class="cs-keyword">this</span>.SmartSession).Person = cls; <span class="cs-comment">//update our current smart session to the session state</span> <span class="cs-keyword">this</span>.SmartSession.PersistToSession(); AcmeSmartQueryString sqs = (AcmeSmartQueryString)<span class="cs-keyword">this</span>.SmartQueryString; sqs.Page = <span class="cs-literal">2</span>.ToString(); sqs.SmartRedirect(<span class="cpp-string">"TestOne.aspx"</span>); }</pre> <p>And this is how you get to it when you need it…</p> <pre>AcmeSmartSession sss = (AcmeSmartSession)<span class="cs-keyword">this</span>.SmartSession; <span class="cs-keyword">if</span>(sss.Person != <span class="cs-keyword">null</span>) sss.Person.Name = <span class="cpp-string">"Bob"</span>;</pre> <p>I am not going to post anything about how to use the Application State stuff since it works the exact same way as the <code>SmartSession</code>. That is the smart state objects in a nutshell – I am currently working on ways to make the persisting calls more efficient by adding an interface to check for a new / dirty / clean object. I will post the enhancements to this framework as they become available.</p> </div> </div> </div> </div> </div> <!--PC和WAP自适应版--> <div id="SOHUCS" sid="1297364922543448064"></div> <script type="text/javascript" src="/views/front/js/chanyan.js"></script> <!-- 文章页-底部 动态广告位 --> <div class="youdao-fixed-ad" id="detail_ad_bottom"></div> </div> <div class="col-md-3"> <div class="row" id="ad"> <!-- 文章页-右侧1 动态广告位 --> <div id="right-1" class="col-lg-12 col-md-12 col-sm-4 col-xs-4 ad"> <div class="youdao-fixed-ad" id="detail_ad_1"> </div> </div> <!-- 文章页-右侧2 动态广告位 --> <div id="right-2" class="col-lg-12 col-md-12 col-sm-4 col-xs-4 ad"> <div class="youdao-fixed-ad" id="detail_ad_2"></div> </div> <!-- 文章页-右侧3 动态广告位 --> <div id="right-3" class="col-lg-12 col-md-12 col-sm-4 col-xs-4 ad"> <div class="youdao-fixed-ad" id="detail_ad_3"></div> </div> </div> </div> </div> </div> </div> <div class="container"> <h4 class="pt20 mb15 mt0 border-top">你可能感兴趣的:(Building a Better ASP.NET 1.1 BasePage Framework 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