温故知新ASP.NET 2.0(C#)(8) - DataSourceControl(数据源控件)

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温故知新ASP.NET 2.0(C#)(8) - DataSourceControl(数据源控件)

作者： webabcd


介绍
在 ASP.NET 2.0 中有几个新的数据源控件，例如，SqlDataSource、ObjectDataSource、XmlDataSource、AccessDataSource 和 SiteMapDataSource。它们全都可以用来从它们各自类型的数据源中检索数据，并且可以绑定到各种数据绑定控件。数据源控件减少了为检索和绑定数据甚至对数据进行排序、分页或编辑而需要编写的自定义代码的数量。

其中 ObjectDataSource 控件可针对各种基础数据存储区（如 SQL 数据库或 XML）启用声明性数据绑定模型。因为页开发人员也常常将数据检索（也可能包含业务逻辑）封装在一个组件对象中，从而在呈现页和数据提供程序之间引入另一个层。ObjectDataSource 控件允许开发人员使用此传统的三层结构构造应用程序，同时仍然能够利用 ASP.NET 中的声明性数据绑定模型的易用性优点。


关键
1、在数据层创建 强类型的DataSet和TableAdapter，TableAdapter查询可以使用现有的存储过程。注：直接把表或存储过程拖进来会自动创建TableAdapter

2、中间层的类用[System.ComponentModel.DataObject]声明为数据组件，CRUD方法分别对应[DataObjectMethod(DataObjectMethodType.Insert)]，[DataObjectMethod(DataObjectMethodType.Select)]，[DataObjectMethod(DataObjectMethodType.Update)]，[DataObjectMethod(DataObjectMethodType.Delete)]

3、web层使用ObjectDataSource展现数据，ObjectDataSource就相当于一个代理。ObjectDataSource只是查找具有匹配的参数名称的方法，它不会使用参数的 Type 或 Size，而只是对参数的名称进行匹配

4、其它
  ·<asp:Parameter />有ConvertEmptyStringToNull属性，默认是true。另外还有Direction属性
  ·注意<asp:BoundField />的这几个属性NullDisplayText，HtmlEncode，ApplyFormatInEditMode，InsertVisible，DataFormatString，ReadOnly
  ·DataKeyNames有多个值的话用“,”分隔，用<asp:ControlParameter />绑定的话给其加一个“PropertyName”属性，值类似如下“SelectedDataKey.Values[0]”
  ·关于绑定：简单属性<%# custID %>；集合<asp:ListBox id="List1" datasource='<%# myArray %>' runat="server">；表达式<%# ( customer.FirstName + " " + customer.LastName ) %>；方法<%# GetBalance(custID) %> 
  ·<%# Eval("field1") %> 和 <%# Bind("field1") %>，Eval是单向绑定，Bind是双向邦定
  ·<asp:ObjectDataSource />有一个OldValuesParameterFormatString属性一般不用，不过如果要处理乐观并发之类的就会用到。当该属性的值为“original_{0}”的时候“original_参数名”则为初始值
  ·还有一些如编程方式给参数赋值，错误处理，得到返回值之类的请看源码


示例
相关存储过程和数据层略，见源码

单例模式的实现
App_Code/Singleton.cs

using  System;
using  System.Data;
using  System.Configuration;
using  System.Web;
using  System.Web.Security;
using  System.Web.UI;
using  System.Web.UI.WebControls;
using  System.Web.UI.WebControls.WebParts;
using  System.Web.UI.HtmlControls;

/**/ /// <summary>
/// Singleton 的摘要说明
/// </summary>
public   class  Singleton < T >  where T :  new ()
{
    public static T Instance
    {
        get { return SingletonCreator.instance; }
    }

    class SingletonCreator
    {
        internal static readonly T instance = new T();
    }
}

中间层代码
App_Code/Test.cs

using  System;
using  System.Data;
using  System.Configuration;
using  System.Web;
using  System.Web.Security;
using  System.Web.UI;
using  System.Web.UI.WebControls;
using  System.Web.UI.WebControls.WebParts;
using  System.Web.UI.HtmlControls;

using  TestDatabaseTableAdapters;
using  System.ComponentModel;

/**/ /// <summary>
/// Test 的摘要说明
/// </summary>
[DataObject]
public   class  Test
{
    [DataObjectMethod(DataObjectMethodType.Select, true)]
    public TestDatabase.TestDataTable GetTest()
    {
        return Singleton<TestTableAdapter>.Instance.GetTest();
    }

    [DataObjectMethod(DataObjectMethodType.Select, false)]
    public TestDatabase.TestDataTable GetTestById(int id)
    {
        return Singleton<TestTableAdapter>.Instance.GetTestById(id);
    }

    [DataObjectMethod(DataObjectMethodType.Insert, true)]
    public int?[] InsertTest(int? parentId, string name, DateTime? publishTime, decimal? price, bool? isGood, out int? minId)
    {
        // 仅为说明如何做错误处理
        if (String.IsNullOrEmpty(name))
            throw new ArgumentException("参数不能是空", "name");

        int? id = null;
        int? count = null;
        minId = null;

        Singleton<TestTableAdapter>.Instance.InsertTest(parentId, name, publishTime, price, isGood, ref id, ref count, ref minId);
        return new int?[] { id, count };
    }

    [DataObjectMethod(DataObjectMethodType.Delete, true)]
    public int? DeleteTest(int id)
    {
        int? rowAffected;

        rowAffected = Singleton<TestTableAdapter>.Instance.DeleteTest(id);
        return rowAffected;
    }

    [DataObjectMethod(DataObjectMethodType.Update, true)]
    public int? UpdateTest(int? id, int? parentId, string name, DateTime? publishTime, decimal? price, bool? isGood)
    {
        int? rowAffected;

        rowAffected = Singleton<TestTableAdapter>.Instance.UpdateTest(id, parentId, name, publishTime, price, isGood);
        return rowAffected;
    }
}

DataSourceControl/Test.aspx

<% @ Page Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeFile="Test.aspx.cs"
    Inherits="DataSourceControl_Test" Title="数据源控件测试"  %>

< asp:Content  ID ="Content1"  ContentPlaceHolderID ="ContentPlaceHolder1"  runat ="Server" >
     < p >
         < asp:Label  ID ="lblMsg"  runat ="server"  ForeColor ="red"   />
     </ p >
     < table  cellpadding ="6" >
         < tr >
             < td  valign ="top" >
                 < asp:DetailsView  ID ="DetailsView1"  runat ="server"  AllowPaging ="True"  AutoGenerateRows ="False"
                    DataKeyNames ="Id"  DataSourceID ="ObjectDataSource1"  Height ="50px"  Width ="125px"  OnItemInserted ="DetailsView1_ItemInserted" >
                     < Fields >
                         < asp:BoundField  DataField ="Id"  HeaderText ="Id"  InsertVisible ="False"  ReadOnly ="True"
                            SortExpression ="Id"   />
                         < asp:BoundField  DataField ="ParentId"  HeaderText ="ParentId"  SortExpression ="ParentId"   />
                         < asp:BoundField  DataField ="Name"  HeaderText ="Name"  SortExpression ="Name"   />
                         < asp:BoundField  DataField ="PublishTime"  HeaderText ="PublishTime"  SortExpression ="PublishTime"
                            InsertVisible ="False"   />
                         < asp:BoundField  DataField ="Price"  HeaderText ="Price"  SortExpression ="Price"  DataFormatString ="{0:c}"  HtmlEncode ="False"   />
                         < asp:CheckBoxField  DataField ="IsGood"  HeaderText ="IsGood"  SortExpression ="IsGood"   />
                         < asp:CommandField  ShowInsertButton ="True"   />
                     </ Fields >
                 </ asp:DetailsView >
             </ td >
             < td  valign ="top" >
                 < asp:DetailsView  ID ="DetailsView2"  runat ="server"  Height ="50px"  Width ="125px"  AutoGenerateRows ="False"  DataKeyNames ="Id"  DataSourceID ="ObjectDataSource2" >
                     < Fields >
                         < asp:BoundField  DataField ="Id"  HeaderText ="Id"  InsertVisible ="False"  ReadOnly ="True"
                            SortExpression ="Id"   />
                         < asp:BoundField  DataField ="ParentId"  HeaderText ="ParentId"  SortExpression ="ParentId"   />
                         < asp:BoundField  DataField ="Name"  HeaderText ="Name"  SortExpression ="Name"   />
                         < asp:BoundField  DataField ="PublishTime"  HeaderText ="PublishTime"  SortExpression ="PublishTime"   />
                         < asp:BoundField  DataField ="Price"  HeaderText ="Price"  SortExpression ="Price"  DataFormatString ="{0:c}"  HtmlEncode ="false"   />
                         < asp:CheckBoxField  DataField ="IsGood"  HeaderText ="IsGood"  SortExpression ="IsGood"   />
                     </ Fields >
                 </ asp:DetailsView >
             </ td >
         </ tr >
     </ table >
     < p >
         < asp:GridView  ID ="GridView1"  runat ="server"  AutoGenerateColumns ="False"  DataKeyNames ="Id"
            DataSourceID ="ObjectDataSource1"  AllowPaging ="True"  AllowSorting ="True"  OnRowUpdating ="GridView1_RowUpdating" >
             < Columns >
                 < asp:CommandField  ShowDeleteButton ="True"  ShowEditButton ="True"  ShowSelectButton ="True"   />
                 < asp:BoundField  DataField ="Id"  HeaderText ="Id"  InsertVisible ="False"  ReadOnly ="True"
                    SortExpression ="Id"   />
                 < asp:BoundField  DataField ="ParentId"  HeaderText ="ParentId"  SortExpression ="ParentId"
                    NullDisplayText ="我的值是NULL"   />
                 < asp:BoundField  DataField ="Name"  HeaderText ="Name"  SortExpression ="Name"   />
                 < asp:BoundField  DataField ="PublishTime"  HeaderText ="PublishTime"  SortExpression ="PublishTime"
                    ReadOnly ="true"   />
                 < asp:BoundField  DataField ="Price"  HeaderText ="Price"  SortExpression ="Price"  DataFormatString ="{0:c}"  HtmlEncode ="false"  ApplyFormatInEditMode ="True"   />
                 < asp:CheckBoxField  DataField ="IsGood"  HeaderText ="IsGood"  SortExpression ="IsGood"   />
             </ Columns >
         </ asp:GridView >
     </ p >
     < asp:ObjectDataSource  ID ="ObjectDataSource1"  runat ="server"  SelectMethod ="GetTest"
        TypeName ="Test"  InsertMethod ="InsertTest"  DeleteMethod ="DeleteTest"  UpdateMethod ="UpdateTest"
        OnInserting ="ObjectDataSource1_Inserting"  OnInserted ="ObjectDataSource1_Inserted" >
         < InsertParameters >
             <% --ConvertEmptyStringToNull属性默认为true-- %>
             < asp:Parameter  Name ="parentId"  Type ="Int32"  ConvertEmptyStringToNull ="true"   />
             < asp:Parameter  Name ="name"  Type ="String"   />
             < asp:Parameter  Name ="publishTime"  Type ="DateTime"   />
             < asp:Parameter  Name ="price"  Type ="Decimal"   />
             < asp:Parameter  Name ="isGood"  Type ="Boolean"   />
             < asp:Parameter  Direction ="Output"  Name ="minId"  Type ="Int32"   />
         </ InsertParameters >
         < DeleteParameters >
             < asp:Parameter  Name ="id"  Type ="Int32"   />
         </ DeleteParameters >
         < UpdateParameters >
             < asp:Parameter  Name ="id"  Type ="Int32"   />
             < asp:Parameter  Name ="parentId"  Type ="Int32"   />
             < asp:Parameter  Name ="name"  Type ="String"   />
             < asp:Parameter  Name ="publishTime"  Type ="DateTime"   />
             < asp:Parameter  Name ="price"  Type ="Decimal"   />
             < asp:Parameter  Name ="isGood"  Type ="Boolean"   />
         </ UpdateParameters >
     </ asp:ObjectDataSource >
     < asp:ObjectDataSource  ID ="ObjectDataSource2"  runat ="server"  OldValuesParameterFormatString ="original_{0}"
        SelectMethod ="GetTestById"  TypeName ="Test" >
         < SelectParameters >
             < asp:ControlParameter  ControlID ="GridView1"  Name ="id"  PropertyName ="SelectedValue"
                Type ="Int32"   />
         </ SelectParameters >
     </ asp:ObjectDataSource >
</ asp:Content >

DataSourceControl/Test.aspx.cs

using  System;
using  System.Data;
using  System.Configuration;
using  System.Collections;
using  System.Web;
using  System.Web.Security;
using  System.Web.UI;
using  System.Web.UI.WebControls;
using  System.Web.UI.WebControls.WebParts;
using  System.Web.UI.HtmlControls;

public  partial  class  DataSourceControl_Test : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    protected void ObjectDataSource1_Inserting(object sender, ObjectDataSourceMethodEventArgs e)
    {
        // 编程方式给参数赋值
        if (e.InputParameters["publishTime"] == null)
        {
            e.InputParameters["publishTime"] = DateTime.Now;
        }
    }

    protected void ObjectDataSource1_Inserted(object sender, ObjectDataSourceStatusEventArgs e)
    {
        // 错误处理
        if (e.Exception != null)
        {
            if (e.Exception.InnerException != null)
            {
                Exception inner = e.Exception.InnerException;

                if (inner is ArgumentException)
                {
                    string paramName = ((ArgumentException)inner).ParamName;
                    lblMsg.Text = string.Concat("参数 ", paramName, " 有问题");
                }
            }
        }
        else
        {
            int?[] ary = (int?[])e.ReturnValue;
            lblMsg.Text = "新插入信息的ID是：" + ary[0].ToString();
            lblMsg.Text += "<br />数据总数是：" + ary[1].ToString();

            lblMsg.Text += "<br />最小ID是：" + e.OutputParameters["minId"].ToString();
        }
    }

    protected void DetailsView1_ItemInserted(object sender, DetailsViewInsertedEventArgs e)
    {
        if (e.Exception != null)
        {
            // 错误已处理
            e.ExceptionHandled = true;
            // DetailsView保持插入状态
            e.KeepInInsertMode = true;
        }
    }

    protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
    {
        // 价格格式转换为decimal格式
        if (e.NewValues["Price"] != null)
            e.NewValues["Price"] = decimal.Parse(e.NewValues["Price"].ToString(), System.Globalization.NumberStyles.Currency);
    }
}

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