精进不休 .NET 4.0 (6) ADO.NET Data Services 1.5(WCF Data Services) 新特性

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精进不休 .NET 4.0 (6) - ADO.NET Data Services 1.5(WCF Data Services) 新特性

作者：webabcd


介绍
ADO.NET Data Services 1.5(WCF Data Services) 的新增功能

• 支持服务端的 RowCount - 获取指定实体集合的成员数（只返回一个整型值，而不会返回实体集合） 
• 支持服务端的分页 - 服务端可以返回分页后的数据，并且在其中还可以包含全部数据总数 
• 支持服务端的 Select - 返回的结果只包括 Select 的字段 
• 支持大数据传输 BLOB（binary large object）
• 支持自定义数据服务 

示例
1、服务端 RowCount 的 Demo
MyDataService.svc.cs

using System;

using System.Collections.Generic;

using System.Data.Services;

using System.Data.Services.Common;

using System.Linq;

using System.ServiceModel.Web;

using System.Web;



namespace DataAccess.DataServices.Service

{

    [System.ServiceModel.ServiceBehavior(IncludeExceptionDetailInFaults = true)]

    public class MyDataService : DataService<MyEntity.AdventureWorksEntities>

    {

        public static void InitializeService(DataServiceConfiguration config)

        {

            config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2;

            config.SetEntitySetAccessRule("Products", EntitySetRights.All);



            // SetEntitySetPageSize(string name, int size) - 新增的方法。用于提供分页后的数据

            //     string name - 指定需要用于分页的实体集合

            //     int size - 分页的页大小

            config.SetEntitySetPageSize("Products", 5);

        }

    }

}

RowCount.aspx.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;



namespace DataAccess.DataServices

{

    public partial class RowCount : System.Web.UI.Page

    {

        protected void Page_Load(object sender, EventArgs e)

        {

            MyDataServiceProxy.AdventureWorksEntities context = new MyDataServiceProxy.AdventureWorksEntities(new Uri("http://localhost:9046/DataServices/Service/MyDataService.svc/"));



            // 支持服务端的 RowCount - 获取指定实体集合的成员数（只返回一个整型值，而不会返回实体集合）

            var productCount = context.Products.Count();

            Response.Write(productCount.ToString());

        }

    }

}



/*

$count - 返回 RowCount，即对应集合的成员数（只返回一个整型值，而不会返回实体集合）

http://localhost:9046/DataServices/Service/MyDataService.svc/Products/$count



$inlinecount=none - 只返回实体集合（分页后的数据）

http://localhost:9046/DataServices/Service/MyDataService.svc/Products?$inlinecount=none



$inlinecount=allpages - 在返回实体集合的基础上（分页后的数据），其中还会包括一个实体集合成员数（分页前的数据）的字段

http://localhost:9046/DataServices/Service/MyDataService.svc/Products?$inlinecount=allpages

*/

2、服务端分页的 Demo
MyDataService.svc.cs

using System;

using System.Collections.Generic;

using System.Data.Services;

using System.Data.Services.Common;

using System.Linq;

using System.ServiceModel.Web;

using System.Web;



namespace DataAccess.DataServices.Service

{

    [System.ServiceModel.ServiceBehavior(IncludeExceptionDetailInFaults = true)]

    public class MyDataService : DataService<MyEntity.AdventureWorksEntities>

    {

        public static void InitializeService(DataServiceConfiguration config)

        {

            config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2;

            config.SetEntitySetAccessRule("Products", EntitySetRights.All);



            // SetEntitySetPageSize(string name, int size) - 新增的方法。用于提供分页后的数据

            //     string name - 指定需要用于分页的实体集合

            //     int size - 分页的页大小

            config.SetEntitySetPageSize("Products", 5);

        }

    }

}

Paging.aspx.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;



namespace DataAccess.DataServices

{

    public partial class Paging : System.Web.UI.Page

    {

        protected void Page_Load(object sender, EventArgs e)

        {

            MyDataServiceProxy.AdventureWorksEntities context = new MyDataServiceProxy.AdventureWorksEntities(new Uri("http://localhost:9046/DataServices/Service/MyDataService.svc/"));



            // 支持服务端的分页 - 服务端可以返回分页后的数据，并且在其中还可以包含全部数据总数

            //     服务端代码：config.SetEntitySetPageSize("Products", 5); 表示每页最多 5 条数据

            //     客户端代码：通过 Skip() 方法来控制需要跳过的记录数

            var products = context.Products.Skip(10);



            foreach (var product in products)

            {

                Response.Write(product.ProductID.ToString() + "<br />");

            }

        }

    }

}



/*

$skip=[int] - 指定需要跳过的记录数

http://localhost:9046/DataServices/Service/MyDataService.svc/Products?$skip=10



$inlinecount=none - 只返回实体集合（分页后的数据）

http://localhost:9046/DataServices/Service/MyDataService.svc/Products?$inlinecount=none



$inlinecount=allpages - 在返回实体集合的基础上（分页后的数据），其中还会包括一个实体集合成员数（分页前的数据）的字段

http://localhost:9046/DataServices/Service/MyDataService.svc/Products?$inlinecount=allpages

*/

3、服务端 Select 的 Demo
MyDataService.svc.cs

using System;

using System.Collections.Generic;

using System.Data.Services;

using System.Data.Services.Common;

using System.Linq;

using System.ServiceModel.Web;

using System.Web;



namespace DataAccess.DataServices.Service

{

    [System.ServiceModel.ServiceBehavior(IncludeExceptionDetailInFaults = true)]

    public class MyDataService : DataService<MyEntity.AdventureWorksEntities>

    {

        public static void InitializeService(DataServiceConfiguration config)

        {

            config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2;

            config.SetEntitySetAccessRule("Products", EntitySetRights.All);



            // SetEntitySetPageSize(string name, int size) - 新增的方法。用于提供分页后的数据

            //     string name - 指定需要用于分页的实体集合

            //     int size - 分页的页大小

            config.SetEntitySetPageSize("Products", 5);

        }

    }

}

QueryProjection.aspx.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;



namespace DataAccess.DataServices

{

    public partial class QueryProjection : System.Web.UI.Page

    {

        protected void Page_Load(object sender, EventArgs e)

        {

            MyDataServiceProxy.AdventureWorksEntities context = new MyDataServiceProxy.AdventureWorksEntities(new Uri("http://localhost:9046/DataServices/Service/MyDataService.svc/"));



            // 支持服务端的 Select - 返回的结果只包括 Select 的字段

            var products = context.Products.Select(p => new { ProductID = p.ProductID, Name = p.Name });



            foreach (var product in products)

            {

                Response.Write(product.ProductID.ToString() + ": " + product.Name + "<br />");

            }

        }

    }

}



/*

$select=[column1,column2,column3,...] - 返回的实体集合数据中只包括指定的字段

http://localhost:9046/DataServices/Service/MyDataService.svc/Products/?$select=ProductID,Name

*/

4、BLOB 的 Demo
BLOBService.svc.cs

/*

ADO.NET Data Services 1.5 - 新增了对大数据传输 BLOB（binary large object）的支持

需要在概念模型（ConceptualModels）中的相关实体上增加属性“m:HasStream="true" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata"”

*/



using System;

using System.Collections.Generic;

using System.Data.Services;

using System.Data.Services.Common;

using System.Linq;

using System.ServiceModel.Web;

using System.Web;



using System.IO;



namespace DataAccess.DataServices.Service

{

    [System.ServiceModel.ServiceBehavior(IncludeExceptionDetailInFaults = true)]

    public class BLOBService : DataService<MyEntity.AdventureWorksEntities>, IServiceProvider

    {

        public static void InitializeService(DataServiceConfiguration config)

        {

            config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2;

            config.SetEntitySetAccessRule("Products", EntitySetRights.All);

        }



        public object GetService(Type serviceType)

        {

            if (serviceType != typeof(System.Data.Services.Providers.IDataServiceStreamProvider))

                return null;



            // 调用服务的时候，如果指定了需要流式传输大数据对象，则通过我们自定义的流式文件传输对象去处理

            return new ProductPhotoStreamProvider();

        }

    }



    /// <summary>

    /// 自定义的一个流式文件传输类，需要实现 System.Data.Services.Providers.IDataServiceStreamProvider 接口

    /// </summary>

    public class ProductPhotoStreamProvider : System.Data.Services.Providers.IDataServiceStreamProvider

    {

        /// <summary>

        /// 获取流。将某个实体的某个属性以流类型的方式返回

        /// </summary>

        /// <param name="entity">相关的实体</param>

        /// <param name="operationContext">当前数据服务请求的上下文</param>

        /// <returns></returns>

        public Stream GetReadStream(object entity, string etag, bool? checkETagForEquality, DataServiceOperationContext operationContext)

        {

            if (entity as MyEntity.Product == null)

                return null;



            int productId = (entity as MyEntity.Product).ProductID;



            using (var context = new MyEntity.AdventureWorksEntities())

            {

                var product = context.Products.First(p => p.ProductID == productId);

                var stream = new MemoryStream(product.ThumbNailPhoto);

                return stream;

            }

        }



        public Uri GetReadStreamUri(object entity, DataServiceOperationContext operationContext)

        {

            return null;

        }



        // 流的内容类型

        public string GetStreamContentType(object entity, DataServiceOperationContext operationContext)

        {

            return "image/jpeg";

        }



        public string GetStreamETag(object entity, DataServiceOperationContext operationContext)

        {

            return null;

        }



        // 流的缓冲区大小

        public int StreamBufferSize

        {

            get { return 64; }

        }



        public void DeleteStream(object entity, DataServiceOperationContext operationContext)

        {

            throw new NotImplementedException();

        }



        public System.IO.Stream GetWriteStream(object entity, string etag, bool? checkETagForEquality, DataServiceOperationContext operationContext)

        {

            throw new NotImplementedException();

        }



        public string ResolveType(string entitySetName, DataServiceOperationContext operationContext)

        {

            throw new NotImplementedException();

        }

    }

}

BLOB.aspx

<%@ Page Title="" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true"

    CodeBehind="BLOB.aspx.cs" Inherits="DataAccess.DataServices.BLOB" %>



<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="server">

</asp:Content>

<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">



    <!--

        查看元数据 - http://localhost:9046/DataServices/Service/BLOBService.svc/$metadata

    -->



    <!--

        Products(714) - 在 Products 集合中取主键为 714 的实体

        $value - 取流数据

    -->

    <img src="http://localhost:9046/DataServices/Service/BLOBService.svc/Products(714)/$value" alt="image" />



</asp:Content>

5、自定义数据服务的 Demo
CustomDataService.svc.cs

/*

ADO.NET Data Services 1.5 - 新增了对自定义数据服务的支持 

*/



using System;

using System.Collections.Generic;

using System.Data.Services;

using System.Data.Services.Common;

using System.Linq;

using System.ServiceModel.Web;

using System.Web;



namespace DataAccess.DataServices.Service

{

    [System.ServiceModel.ServiceBehavior(IncludeExceptionDetailInFaults = true)]

    public class CustomDataService : DataService<OrderContext>

    {

        public static void InitializeService(DataServiceConfiguration config)

        {

            config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2;

            config.SetEntitySetAccessRule("Orders", EntitySetRights.All);

            config.SetEntitySetAccessRule("Products", EntitySetRights.All);

        }

    }



    /// <summary>

    /// 数据上下文

    /// </summary>

    public class OrderContext

    {

        static List<Order> _orders;

        static List<Product> _products;

        static OrderContext()

        {

            _orders = new List<Order>

            {

                new Order { OrderId = 0, Customer="webabcd"},

                new Order { OrderId = 1, Customer="webabcdefg"}

            };



            _products = new List<Product>

            {

                new Product { ProductId = 0, ProductName="wii", Price=100 }, 

                new Product { ProductId = 1, ProductName="xbox360", Price=200 }, 

                new Product { ProductId = 2, ProductName="ps3", Price = 300 }, 

                new Product { ProductId = 3, ProductName="nds", Price=50 },

                new Product { ProductId = 4, ProductName="psp", Price=100 }

            };



            _orders[0].Items.Add(_products[0]);

            _orders[0].Items.Add(_products[1]);



            _orders[1].Items.Add(_products[2]);

            _orders[1].Items.Add(_products[3]);

            _orders[1].Items.Add(_products[4]);

        }





        public IQueryable<Order> Orders

        {

            get { return _orders.AsQueryable<Order>(); }

        }



        public IQueryable<Product> Products

        {

            get { return _products.AsQueryable<Product>(); }

        }

    }



    /*

     * DataServiceKeyAttribute() - 指定主键字段

     * EntityPropertyMapping() - 实体属性到 ATOM 字段的映射，以便生成一个友好格式的 Feed 

     */

    [EntityPropertyMapping("Customer", SyndicationItemProperty.AuthorName, SyndicationTextContentKind.Plaintext, true)]

    [DataServiceKeyAttribute("OrderId")]

    public class Order

    {

        public int OrderId { get; set; }

        public string Customer { get; set; }



        private List<Product> _items;

        public List<Product> Items

        {

            get

            {

                if (_items == null)

                    _items = new List<Product>();



                return _items;

            }

            set

            {

                _items = value;

            }

        }

    }



    [DataServiceKeyAttribute("ProductId")]

    public class Product

    {

        public int ProductId { get; set; }

        public string ProductName { get; set; }

        public int Price { get; set; }

    }

}

CustomDataService.aspx.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;



namespace DataAccess.DataServices

{

    public partial class CustomDataService : System.Web.UI.Page

    {

        protected void Page_Load(object sender, EventArgs e)

        {

            // 使用自定义数据服务提供的服务

            CustomDataServiceProxy.OrderContext context = new CustomDataServiceProxy.OrderContext(new Uri("http://localhost:9046/DataServices/Service/CustomDataService.svc/"));



            var orders = context.Orders;



            foreach (var order in orders)

            {

                Response.Write(order.OrderId.ToString() + "<br />");

            }

        }

    }

}

注：
以 URI 语法的方式查询 ADO.NET 数据服务的形式如下：
http://[Url]/[ServiceName]/[EntityName]/[NavigationOptions]?[QueryOptions]
详细语法参看 MSDN


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