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

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

作者： webabcd

介绍
ADO.NET Data Services 1.5 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

代码

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

代码

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

代码

Paging.aspx.cs

代码

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

代码

QueryProjection.aspx.cs

代码

4、BLOB 的 Demo
BLOBService.svc.cs

代码

/*
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

代码

<% @ 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" >

     

     
     < 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

代码

/*
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

代码