data and bindings

WinJS为我们提供了一些数据绑定的方法来实现MVC和MVVC这种架构,使我们对应用数据的管理和更新变得更加方便

首先,需要创建一个viewmodel,新建一个js文件,并在文件中添加如下代码:

///<reference path="//Microsoft.WinJS.1.0/js/base.js"/>
///<reference path="//Microsoft.WinJS.1.0/js/ui.js"/>

(function () {

    "use strict"

    WinJS.Namespace.define("ViewModel.UserData", {

        
            _shoppingItems:[],
            _preferredStores:[],
            homeZipCode: null,
        
            getStore: function () {
                return this._preferredStore;
            },

            addStore: function (newStore) {
                this._preferredStore.push(newStore);
            },

            getItems: function () {
                return this._shoppingItems;
            },

            addItems: function (newName, newQuanity, newStore) {
                this._shoppingItems.push({
                    item: newName,
                    quanity: newQuanity,
                    store:newStore
                });
            }
    });

    ViewModel.UserData.homeZipCode = "NY 10086";

    ViewModel.UserData.addStore("Yuki");
    ViewModel.UserData.addStore ("Nike");

    ViewModel.UserData.addItems("Kobe8", 1, "Nike");


})();

这样就定义了一个全局变量,在整个工程里都可以使用,在html文件中添加viewmodel.js的路径:

<script src="viewmodel.js的url"></script>

第一种bindings叫做基本声明绑定,即只能绑定简单变量,类和数组等不能通过这种方法绑定

在html文件中添加一个span,用来显示绑定的内容:

        The Zip Code is <span id="zipCode" class="TheZipCode" data-win-bind="innerText:UserData.homeZipCode"></span>

homeZipCode为viewmodel.js文件中所定义的ViewModel.UserData里的一个简单变量

然后再default.js文件的app.onactivated函数里添加如下代码:

app.onactivated = function (args) {
        if (args.detail.kind === activation.ActivationKind.launch) {
            if (args.detail.previousExecutionState !== activation.ApplicationExecutionState.terminated) {
                // TODO: This application has been newly launched. Initialize
                // your application here.
                performIntialSetup(args);
            } else {
                // TODO: This application has been reactivated from suspension.
                // Restore application state here.
            }
            args.setPromise(WinJS.UI.processAll());
        }
    };

performInitialSetup(e)函数的实现如下:

WinJS.Binding.processAll(document.body, ViewModel);

这样就完成了基本声明绑定,可能大家会有疑问,为什么span的data-win-bind=“UserData.homeZipCode”而不是ViewModel.UserData.homeZipCode,这是因为Declarative data bindings are relative to the data source

可是这种绑定只能显示数据,并不能实现同步更新修改,这时,动态绑定可以帮我们实现

这里需要用到一个函数WinJS.Binding.as(),把ViewModel的成员作为一个object作为WinJS.Binding.as函数的参数,对viewmodel.js文件作以下修改:

WinJS.Namespace.define("ViewModel", {

        UserData:WinJS.Binding.as({

            _shoppingItems:[],
            _preferredStores:[],

            homeZipCode: null,
        
            getStore: function () {
                return this._preferredStore;
            },

            addStore: function (newStore) {
                this._preferredStore.push(newStore);
            },

            getItems: function () {
                return this._shoppingItems;
            },

            addItems: function (newName, newQuanity, newStore) {
                this._shoppingItems.push({
                    item: newName,
                    quanity: newQuanity,
                    store:newStore
                });
            }

        }),
    });

在html文件里添加一个输入文本框和一个更新按钮:

.Enter a new zip code:<input id="zipCodeInput" data-win-bind="value:UserData.homeZipCode" />
        <button id="update">update</button>

接着,在之前的performInitialSetup(e)函数里添加代码,是在点击更新按钮之后,以输入文本框里的内容重置homeZipCode的值:

WinJS.Utilities.query('#update').listen("click", function (e) {
            ViewModel.UserData.homeZipCode = WinJS.Utilities.query('#zipCodeInput')[0].value;
        });

这样在输入一些东西之后,点击更新,就可以看到之前绑定的span的内容也更新为输入的东西

完成了简单变量的绑定,接下来便是一些复杂变量的绑定了,如数组

这时,需要WinJS.Binding.List(),UserData中的两个数组不再是私有成员,必须将其定义为全局变量,在viewmodel.js里做如下修改:

var shoppingItems =new WinJS.Binding.List();
    var preferredStore =new WinJS.Binding.List();

    WinJS.Namespace.define("ViewModel", {

        UserData:WinJS.Binding.as({


            homeZipCode: null,
        
            getStore: function () {
                return preferredStore;
            },

            addStore: function (newStore) {
                preferredStore.push(newStore);
            },

            getItems: function () {
                return shoppingItems;
            },

            addItems: function (newName, newQuanity, newStore) {
                shoppingItems.push({
                    item: newName,
                    quanity: newQuanity,
                    store:newStore
                });
            }

        }),
   });

在html中添加additem按钮和removeitem按钮还有一个显示最后添加的Item的newName的span:

the last item is:<span id="item"></span>
        <button id="additem">Add Item</button>
        <button id="removeitem">Remove Item</button>

在performIntialSetup(e)函数里如入下如下代码:

WinJS.Utilities.query('button').listen("click", function (e) {
            if (this.id == "additem") {
                console.log("additem succeed");
                ViewModel.UserData.addItems("Kobe9", 1, "Nike");
            }
            else
                if(this.id=="removeitem")
                {
                    ViewModel.UserData.getItems().pop();
                }
        });

        var setValue = function () {
            var list = ViewModel.UserData.getItems();
            document.getElementById('item').innerText = list.getAt(list.length - 1).item;
        };

        var eventTypes = ["itemchanged", "iteminserted", "itemmoved", "itemremoved"];
        
        eventTypes.forEach(function (type) {
            ViewModel.UserData.getItems().addEventListener(type, setValue);
        });
        

        setValue();

eventType的设置是相当重要的,这样,当有新item插入,它才会响应并更新最后插入的item的名字
至此,也完成了数组的绑定

 

 

 

 


 


 

 

 

 

 

 

 

 

 

 


 


 

 

 

 

 


 

 

 

 

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