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再接再厉VS 2008 sp1 + .NET 3.5 sp1(7) - Data Services(数据服务)


作者:webabcd


介绍
以Northwind为示例数据库,演示ADO.NET Data Services(数据服务)
  • DataService<T> - ADO.NET 数据服务的主入口点。 T 为数据源类名
  • IDataServiceConfiguration.SetEntitySetAcce***ule(string name, EntitySetRights rights) - 为指定实体集设置访问规则
  • QueryInterceptorAttribute - 声明在方法上的查询拦截器
  • DataServiceContext - 数据服务的上下文
  • DataServiceQuery - 以指定的 URI 语法查询数据服务


示例
服务端
Service.cs
using System;
using System.Data.Services;
using System.Collections.Generic;
using System.Linq;
using System.ServiceModel.Web;

using VS2008SP1.Business;
using System.Linq.Expressions;

// DataService<T> - ADO.NET 数据服务的主入口点。 T 为数据源类名
public class Service : DataService<VS2008SP1.Business.NorthwindEntities>
{
        // 初始化涉及服务范围的策略(仅调用一次)
static void InitializeService() static void InitializeService(IDataServiceConfiguration config)
        {
                /**//*
                 * IDataServiceConfiguration.SetEntitySetAcce***ule(string name, EntitySetRights rights) - 为指定实体集设置访问规则
                 *         name - 实体集名称(* 为全部)
                 *         rights - 设置对指定实体集的操作权限 [System.Data.Services.EntitySetRights 枚举]
                 * EntitySetRights.None - 权限为:无任何权限    
                 * EntitySetRights.All - 权限为:全部权限    
                 * EntitySetRights.ReadSingle - 权限为:只能读取数据集内的某一条数据
                 * EntitySetRights.ReadMultiple - 权限为:可读取数据集内的全部数据
                 * EntitySetRights.WriteAppend - 权限为:插入    
                 * EntitySetRights.WriteReplace - 权限为:更新    
                 * EntitySetRights.WriteDelete - 权限为:删除
                 * EntitySetRights.WriteMerge - 权限为:合并数据    
                 * EntitySetRights.AllRead - 权限为:全部可读    
                 * EntitySetRights.AllWrite - 权限为:全部可写    
                 */
                config.SetEntitySetAcce***ule("*", EntitySetRights.All);
                
                // config.SetEntitySetAcce***ule("*", EntitySetRights.AllRead | EntitySetRights.AllWrite);
        }

        /**//*
         *    QueryInterceptorAttribute - 声明在方法上的查询拦截器
         *            方法名任意(不带参数),返回值必须为一个 Expression<Func<T, bool>> 表达式,T 为需要过滤的实体集类名
         */
        [QueryInterceptor("Orders")]
Expression<Func<Orders, bool>> FilterOrders() Expression<Func<Orders, bool>> FilterOrders()
        {
                // 本例为无论在任何情况下,返回的 Orders 都是 ContactName 为 Paul Henriot 的 Orders
                return o => o.Customers.ContactName == "Paul Henriot";
        }
}
 
 
1、添加、查询、更新和删除的Demo
Demo.aspx
<%@ Page Title="添加、查询、更新和删除的Demo" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true"
        CodeFile="Demo.aspx.cs" Inherits="DataServices_Demo" %>

<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server">
        <div style="margin: 10px;">
                CategoryName:<asp:TextBox ID="txtCategoryName" runat="server" />
                Description:<asp:TextBox ID="txtDescription" runat="server" />
                <asp:Button ID="btnAddCategory" runat="server" Text="添加产品类别" OnClick="btnAddCategory_Click" />
        </div>
        <div style="margin: 10px;">
                <asp:GridView ID="GridView1" DataKeyNames="CategoryID" runat="server" AutoGenerateColumns="false"
                        OnRowDeleting="GridView1_RowDeleting" OnRowCancelingEdit="GridView1_RowCancelingEdit"
                        OnRowEditing="GridView1_RowEditing" OnRowUpdating="GridView1_RowUpdating" OnSelectedIndexChanged="GridView1_SelectedIndexChanged">
                        <Columns>
                                <asp:BoundField DataField="CategoryID" HeaderText="ID" ReadOnly="true" />
                                <asp:BoundField DataField="CategoryName" HeaderText="CategoryName" />
                                <asp:BoundField DataField="Description" HeaderText="Description" />
                                <asp:CommandField ShowSelectButton="True" ShowEditButton="True" ShowDeleteButton="True">
                                </asp:CommandField>
                        </Columns>
                </asp:GridView>
        </div>
        <div style="margin: 10px;">
                <asp:GridView ID="GridView2" runat="server">
                </asp:GridView>
        </div>
</asp:Content>
 
Demo.aspx.cs
// 客户端用到的只有以下两个类
// System.Data.Services.Client.DataServiceContext - 数据服务的上下文
// System.Data.Services.Client.DataServiceQuery - 以指定的 URI 语法查询数据服务

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

using MyDataService;

public partial class DataServices_Demo : System.Web.UI.Page
{
        // ADO.NET 数据服务的地址
        Uri _uri = new Uri("http://localhost:7002/DataServices/Service.svc/", UriKind.Absolute);

void Page_Load() void Page_Load(object sender, EventArgs e)
        {
                if (!Page.IsPostBack)
                {
                        BindData();
                }
        }

        void BindData()
        {
                // NorthwindEntities - 继承自 DataServiceContext ,其构造函数的参数为数据服务的 URI 地址
                NorthwindEntities ctx = new NorthwindEntities(_uri);

                // 将 System.Data.Services.Client.DataServiceQuery<Categories> 绑定到 Gridview1
                GridView1.DataSource = ctx.Categories;
                GridView1.DataBind();
        }

void btnAddCategory_Click() void btnAddCategory_Click(object sender, EventArgs e)
        {
                NorthwindEntities ctx = new NorthwindEntities(_uri);

                Categories category = new Categories();
                category.CategoryName = txtCategoryName.Text;
                category.Description = txtDescription.Text;

                // DataServiceContext.Timeout - 超时时间
                // DataServiceContext.MergeOption - 当前数据上下文与数据服务的数据的同步选项 [System.Data.Services.Client.MergeOption 枚举]
                //         AppendOnly - 追加。默认值
                //         OverwriteChanges - 以新结果为准
                //         PreserveChanges - 以原结果为准
                //         NoTracking - 取消变更跟踪,不会使用 ObjectStateManager,减少执行查询的时间,所有返回的实体将是分离的状态(detached state)
                ctx.MergeOption = System.Data.Services.Client.MergeOption.AppendOnly;

                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);

                        // DataServiceContext.SetLink(Object source, string sourceProperty, Object target) - 在指定对象上创建新的连接,Added状态,SaveChanges() 的时候会一起发送到数据服务。多对一关系
                        //         source - 源对象
                        //         sourceProperty - 源对象上的属性,用于标识目标对象的类型
                        //         target - 目标对象
                        ctx.SetLink(product, "Categories", category);
                        // DataServiceContext.AddLink(Object source, string sourceProperty, Object target) - 在指定对象上创建新的连接,Added状态,SaveChanges() 的时候会一起发送到数据服务。一对多关系
                        // DataServiceContext.DeleteLink(Object source, string sourceProperty, Object target) - 在指定的对象上删除连接,Deleted状态,SaveChanges() 的时候会一起发送到数据服务
                }

                // DataServiceContext.SaveChanges() - 将所有更新保存到相关存储区中
                //         SaveChangesOptions.Batch - 一个 http 提交所有操作
                //         SaveChangesOptions.ContinueOnError - 一个 http 一个操作,某操作出错仍将处理后续操作(不能与 Batch 共存)
                //         SaveChangesOptions.ReplaceOnUpdate -    
                //         SaveChangesOptions.None - 出错则停止
                ctx.SaveChanges(System.Data.Services.Client.SaveChangesOptions.Batch);

                Page.ClientScript.RegisterStartupScript(this.GetType(), "js", "alert('CategoryID: " + category.CategoryID + "');", true);

                GridView1.EditIndex = -1;
                BindData();
        }

void GridView1_RowDeleting() void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
        {
                NorthwindEntities ctx = new NorthwindEntities(_uri);

                var categoryId = (int)GridView1.DataKeys[e.RowIndex].Value;

                var category = ctx.Categories.Where(p => p.CategoryID == categoryId).First();

                // DataServiceContext.LoadProperty(Object entity, string propertyName) - 加载指定对象的指定实体属性
                //         entity - 包含要加载的实体属性的实体
                //         propertyName - 需要加载的实体属性的名称
                ctx.LoadProperty(category, "Products");
                foreach (var product in category.Products)
                {
                        ctx.DeleteObject(product);
                }

                ctx.DeleteObject(category);

                ctx.SaveChanges();

                GridView1.EditIndex = -1;
                BindData();
        }

void GridView1_SelectedIndexChanged() void GridView1_SelectedIndexChanged(object sender, EventArgs e)
        {
                NorthwindEntities ctx = new NorthwindEntities(_uri);

                var categoryId = (int)GridView1.SelectedDataKey.Value;

                // 查找当前选中的类别下的产品集合
                var products = ctx.Products.Where(p => p.Categories.CategoryID == categoryId);

                // 将 System.Linq.IQueryable<Products> 绑定到 GridView2
                GridView2.DataSource = products;
                GridView2.DataBind();
        }

void GridView1_RowUpdating() void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
        {
                NorthwindEntities ctx = new NorthwindEntities(_uri);

                var categoryId = (int)GridView1.DataKeys[e.RowIndex].Value;

                var category = ctx.Categories.Where(p => p.CategoryID == categoryId).First();

                category.CategoryName = ((TextBox)GridView1.Rows[e.RowIndex].Cells[1].Controls[0]).Text;
                category.Description = ((TextBox)GridView1.Rows[e.RowIndex].Cells[2].Controls[0]).Text;

                ctx.UpdateObject(category);
                ctx.SaveChanges();

                GridView1.EditIndex = -1;
                BindData();
        }

void GridView1_RowEditing() void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
        {
                GridView1.EditIndex = e.NewEditIndex;
                BindData();
        }

void GridView1_RowCancelingEdit() void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
        {
                GridView1.EditIndex = -1;
                BindData();
        }
}
 
 
2、其他知识点
Demo2.aspx
<%@ Page Title="其它" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true"
        CodeFile="Demo2.aspx.cs" Inherits="DataServices_Demo2" %>

<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server">
        <div id="result" runat="server">
        </div>
</asp:Content>
 
Demo2.aspx.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

using MyDataService;
using System.Data.Services.Client;

public partial class DataServices_Demo2 : System.Web.UI.Page
{
        // ADO.NET 数据服务的地址
        Uri _uri = new Uri("http://localhost:7002/DataServices/Service.svc/", UriKind.Absolute);

void Page_Load() void Page_Load(object sender, EventArgs e)
        {
                // 以 URI 语法的方式查询 ADO.NET 数据服务
                Demo();

                // 异步方式查询 ADO.NET 数据服务
                Demo2();

                // 演示查询拦截器的 Demo
                Demo3();

                // 演示以 JSON 作为响应格式的 Demo
                Demo4();
        }

        void Demo()
        {
                DataServiceContext ctx = new DataServiceContext(_uri);

                // 以 URI 语法的方式查询 ADO.NET 数据服务,详细语法参看 MSDN
                // http://[Url]/[ServiceName]/[EntityName]/[NavigationOptions]?[QueryOptions]
                DataServiceQuery<Categories> categories = ctx.CreateQuery<Categories>("/Categories");

                foreach (var c in categories)
                {
                        result.InnerHtml += c.CategoryID + ",";
                }

                result.InnerHtml += "<br /><br />";
        }

        void Demo2()
        {
                DataServiceContext ctx = new DataServiceContext(_uri);

                DataServiceQuery<Categories> query = ctx.CreateQuery<Categories>("/Categories");

                // 异步方式查询 ADO.NET 数据服务
                query.BeginExecute(
                        delegate(IAsyncResult ar)
                        {
                                foreach (var c in query.EndExecute(ar))
                                {
                                        result.InnerHtml += c.CategoryID + ",";
                                }

                                result.InnerHtml += "<br /><br />";
                        },
                        null);
        }

        void Demo3()
        {
                NorthwindEntities ctx = new NorthwindEntities(_uri);

                // 因为设置了查询拦截器,所以只能收到 ContactName 为 Paul Henriot 的 Orders
                foreach (var o in ctx.Orders)
                {
                        result.InnerHtml += o.OrderID + ",";
                }

                result.InnerHtml += "<br /><br />";
        }

        void Demo4()
        {
                System.Net.WebClient client = new System.Net.WebClient();
                // 需要以 json 格式返回结果的话,需要设置以下 header
                client.Headers.Add("accept", "application/json");
                // client.Headers.Add("accept", "application/xml"); xml/atom 格式
                // client.Headers.Add("accept", "*/*"); xml/atom 格式,默认值
                result.InnerHtml += HttpUtility.HtmlEncode(client.DownloadString(_uri));
        }
}