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稳扎稳打Silverlight(28) - 2.0通信之调用ADO.NET Data Services(数据服务)


作者:webabcd


介绍
Silverlight 2.0 调用 ADO.NET Data Services (数据服务)。本文以 Northwind 数据库为示例数据库,做一个添加、查询、更新和删除的Demo 
    在 Silverlight 2.0 中调用数据服务只能使用异步方式调用。另外,数据服务要与 Silverlight 宿主放在相同的域上
    System.Data.Services.Client.DataServiceContext - 数据服务上下文
    System.Data.Services.Client.DataServiceQuery - 以指定的 URI 语法查询数据服务
    AddObject(), UpdateObject(), DeleteObject() - 本别用于添加, 更新, 删除实体
    BeginExecute()/EndExecute(), BeginExecuteBatch()/EndExecuteBatch - 用于执行某一个 DataServiceQuery 查询或批量执行(将一组查询一次性地提交到数据服务)
    BeginSaveChanges()/EndSaveChanges() - 用于提交对实体的修改(增,删,改)
    BeginLoadProperty()/EndLoadProperty() - 用于加载指定的属性的值,加载导航属性的时候需要用到它
    AddLink(), SetLink(), DeleteLink() - 分别为创建连接,Added状态(一对多);创建连接,Added状态(多对一);删除连接,Deleted状态


在线DEMO
http://webabcd.blog.51cto.com/1787395/342779 


示例
1、数据服务
NorthwindDataService.svc
<%@ ServiceHost Language="C#" Factory="System.Data.Services.DataServiceHostFactory, System.Data.Services, Version=3.5.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" Service="Silverlight20.Web.DataService.NorthwindDataService" %>
 
NorthwindDataService.svc.cs
using System;
using System.Collections.Generic;
using System.Data.Services;
using System.Linq;
using System.ServiceModel.Web;
using System.Web;

namespace Silverlight20.Web.DataService
{
        public class NorthwindDataService : DataService<NorthwindEntities>
        {
                public static void InitializeService(IDataServiceConfiguration config)
                {
                        config.SetEntitySetAcce***ule("*", EntitySetRights.All);
                }
        }
}
 
 
2、Silverlight 调用数据服务
DataService.xaml
<UserControl x:Class="Silverlight20.Communication.DataService"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:data="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Data">

        <StackPanel HorizontalAlignment="Left" Margin="5">

                <TextBlock x:Name="lblMsg" Margin="10" Foreground="Red" />

                <StackPanel Orientation="Horizontal">
                        <TextBlock x:Name="lblCategoryName" Text="类别名称" Margin="10" />
                        <TextBox x:Name="txtCategoryName" Width="100" Margin="10" />
                        <TextBlock x:Name="lblDescription" Text="类别备注" Margin="10" />
                        <TextBox x:Name="txtDescription" Width="100" Margin="10" />
                        <Button x:Name="btnAdd" Content="添加" Margin="10" Click="btnAdd_Click" />
                </StackPanel>

                <StackPanel Orientation="Horizontal">
                        <Button x:Name="btnUpdate" Content="更新选中" Margin="10" Click="btnUpdate_Click" />
                        <Button x:Name="btnDelete" Content="删除选中" Margin="10" Click="btnDelete_Click"    />
                </StackPanel>

                <data:DataGrid Name="dataGrid1" Margin="10" AutoGenerateColumns="False" ItemsSource="{Binding}"
                        SelectionChanged="DataGrid_SelectionChanged">
                        <data:DataGrid.Columns>
                                <data:DataGridTextColumn Header="类别ID" Binding="{Binding CategoryID}" />
                                <data:DataGridTextColumn Header="类别名称" Binding="{Binding CategoryName}" />
                                <data:DataGridTextColumn Header="类别备注" Binding="{Binding Description}" />
                        </data:DataGrid.Columns>
                </data:DataGrid>

                <data:DataGrid Name="dataGrid2" Margin="10" AutoGenerateColumns="False" ItemsSource="{Binding}">
                        <data:DataGrid.Columns>
                                <data:DataGridTextColumn Header="产品ID" Binding="{Binding ProductID}" />
                                <data:DataGridTextColumn Header="产品名称" Binding="{Binding ProductName}" />
                        </data:DataGrid.Columns>
                </data:DataGrid>

        </StackPanel>

</UserControl>
 
DataService.xaml.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

using System.Data.Services.Client;
using System.Collections.ObjectModel;
using Silverlight20.NorthwindDataService;

namespace Silverlight20.Communication
{
        public partial class DataService : UserControl
        {
                // 配置服务地址,数据服务要与 Silverlight 宿主放在相同的域上
                Uri uri = new Uri("DataService/NorthwindDataService.svc", UriKind.Relative);
                NorthwindEntities ctx;
                ObservableCollection<Categories> categories;
                ObservableCollection<Products> products;

                public DataService()
                {
                        InitializeComponent();

                        this.Loaded += new RoutedEventHandler(DataService_Loaded);
                }

                void DataService_Loaded(object sender, RoutedEventArgs e)
                {
                        // 实例化 DataServiceContext
                        ctx = new NorthwindEntities(uri);
                        // 初始化 Categories 集合,为了做 OneWay ,所以是 ObservableCollection<Categories> 类型
                        categories = new ObservableCollection<Categories>();
                        // 初始化 Products 集合,为了做 OneWay ,所以是 ObservableCollection<Products> 类型
                        products = new ObservableCollection<Products>();

                        BindCategory();
                }

                private void BindCategory()
                {
                        DataServiceQuery<Categories> query = ctx.Categories;

                        // IAsyncResult BeginExecute(AsyncCallback callback, object state) - 以异步方式发出请求
                        //         AsyncCallback callback - 经典的 AsyncCallback 委托,指定回调方法
                        //         object state - 传递给回调方法的自定义对象,此处必须是 DataServiceQuery<T> 类型
                        query.BeginExecute(OnBindCategoryCompleted, query);
                        // RequestUri - 请求服务的地址,因为数据服务发布的是REST,所以也可以用自己构造 URI 的方式去调用数据服务,详细的 URI 语法请参看 MSDN
                        lblMsg.Text = "读取类别数据中。。。" + query.RequestUri.ToString();
                }

                void OnBindCategoryCompleted(IAsyncResult ar)
                {
                        try
                        {
                                var query = ar.AsyncState as DataServiceQuery<Categories>;

                                // EndExecute(IAsyncResult ar) - 获取异步查询的结果
                                var result = query.EndExecute(ar);

                                foreach (var item in result)
                                {
                                        categories.Add(item);
                                }

                                this.Dispatcher.BeginInvoke(() =>
                                {
                                        dataGrid1.DataContext = categories;
                                        lblMsg.Text = "";
                                });
                        }
                        catch (DataServiceRequestException ex)
                        {
                                lblMsg.Text = ex.ToString();
                        }
                }

                private void btnAdd_Click(object sender, RoutedEventArgs e)
                {
                        Categories category = new Categories();
                        category.CategoryName = txtCategoryName.Text;
                        category.Description = txtDescription.Text;

                        ctx.AddToCategories(category);

                        for (int i = 0; i < 10; i++)
                        {
                                var product = new Products() { ProductName = "测试用" + i.ToString() };
                                product.Categories = category;
                                ctx.AddToProducts(product);
                                // 多对一关系,使用 SetLink 建立连接,BeginSaveChanges() 的时候会一起发送到数据服务
                                ctx.SetLink(product, "Categories", category);
                        }

                        ctx.BeginSaveChanges(OnAddCompleted, category);
                        lblMsg.Text = "新增数据中。。。";
                }

                void OnAddCompleted(IAsyncResult ar)
                {
                        try
                        {
                                var x = ctx.EndSaveChanges(ar);

                                categories.Add(ar.AsyncState as Categories);

                                this.Dispatcher.BeginInvoke(() =>
                                {
                                        lblMsg.Text = "";
                                });
                        }
                        catch (DataServiceRequestException ex)
                        {
                                lblMsg.Text = ex.ToString();
                        }
                }

                private void DataGrid_SelectionChanged(object sender, SelectionChangedEventArgs e)
                {
                        var category = e.AddedItems[0] as Categories;
                        BindProduct(category.CategoryID);
                }

                private void BindProduct(int categoryId)
                {
                        // 可以使用 Lambda 表达式或查询语法,然后将其转换为 DataServiceQuery<T> 再使用
                        DataServiceQuery<Products> query =
                                (from p in ctx.Products where p.Categories.CategoryID == categoryId select p) as DataServiceQuery<Products>;

                        lblMsg.Text = "读取产品数据中。。。";
                        query.BeginExecute(OnBindProductCompleted, query);
                }

                void OnBindProductCompleted(IAsyncResult ar)
                {
                        try
                        {
                                var query = ar.AsyncState as DataServiceQuery<Products>;

                                var result = query.EndExecute(ar);
                                products.Clear();
                                foreach (var item in result)
                                {
                                        products.Add(item);
                                }

                                this.Dispatcher.BeginInvoke(() =>
                                {
                                        dataGrid2.DataContext = products;
                                        lblMsg.Text = "";
                                });
                        }
                        catch (DataServiceRequestException ex)
                        {
                                lblMsg.Text = ex.ToString();
                        }
                }

                private void btnDelete_Click(object sender, RoutedEventArgs e)
                {
                        if (dataGrid1.SelectedItem != null)
                        {
                                try
                                {
                                        Categories category = dataGrid1.SelectedItem as Categories;

                                        DeleteCategory(category);
                                        lblMsg.Text = "删除中。。。";
                                }
                                catch (DataServiceRequestException ex)
                                {
                                        lblMsg.Text = ex.ToString();
                                }
                        }
                }

                private void DeleteCategory(Categories category)
                {
                        try
                        {
                                // BeginLoadProperty(object entity, string propertyName, AsyncCallback callback, object state) - 开始加载指定属性的值的异步操作
                                //         object entity - 需要加载属性的所属实体    
                                //         string propertyName - 需要加载属性的名称
                                //         AsyncCallback callback - 经典的 AsyncCallback 委托,指定回调方法
                                //         object state - 传递给回调方法的自定义对象
                                ctx.BeginLoadProperty(category, "Products", OnLoadPropertyCompleted, category);
                        }
                        catch (DataServiceRequestException ex)
                        {
                                lblMsg.Text = ex.ToString();
                        }
                }

                void OnLoadPropertyCompleted(IAsyncResult ar)
                {
                        Categories category = ar.AsyncState as Categories;

                        try
                        {
                                // EndLoadProperty(IAsyncResult ar) - 完成加载指定属性的值的这个异步操作
                                ctx.EndLoadProperty(ar);

                                foreach (Products product in category.Products)
                                {
                                        // 在指定的对象上删除指定的连接,BeginSaveChanges() 的时候会一起发送到数据服务
                                        ctx.DeleteLink(category, "Products", product);
                                }

                                ctx.DeleteObject(category);
                                ctx.BeginSaveChanges(OnDeleteCategoryCompleted, null);

                                categories.Remove(category);
                        }
                        catch (DataServiceRequestException ex)
                        {
                                lblMsg.Text = ex.ToString();
                        }
                }

                void OnDeleteCategoryCompleted(IAsyncResult ar)
                {
                        try
                        {
                                ctx.EndSaveChanges(ar);
                                lblMsg.Text = "";

                        }
                        catch (DataServiceRequestException ex)
                        {
                                lblMsg.Text = ex.ToString();
                        }
                }

                private void btnUpdate_Click(object sender, RoutedEventArgs e)
                {
                        if (dataGrid1.SelectedItem != null)
                        {
                                try
                                {
                                        Categories category = dataGrid1.SelectedItem as Categories;

                                        ctx.UpdateObject(category);
                                        ctx.BeginSaveChanges(OnUpdateCategoryCompleted, category);
                                        lblMsg.Text = "更新中。。。";
                                }
                                catch (DataServiceRequestException ex)
                                {
                                        lblMsg.Text = ex.ToString();
                                }
                        }
                }

                void OnUpdateCategoryCompleted(IAsyncResult ar)
                {
                        try
                        {
                                ctx.EndSaveChanges(ar);
                                lblMsg.Text = "";

                        }
                        catch (DataServiceRequestException ex)
                        {
                                lblMsg.Text = ex.ToString();
                        }
                }
        }
}