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://www.cnblogs.com/webabcd/archive/2008/10/09/1307486.html

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.SetEntitySetAccessRule("*", 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>

</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();

}

OK
[源码下载]

posted @ 2009-03-12 08:07 webabcd 阅读(6999) 评论(9) 编辑收藏举报

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