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

2022-08-05 08:25:36

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

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>
        {
static void InitializeService() 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
        {
void Page_Load() 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

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
        {
void Page_Load() 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

QueryProjection.aspx.cs

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
        {
static void InitializeService() static void InitializeService(DataServiceConfiguration config)
                {
                        config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2;
                        config.SetEntitySetAccessRule("Products", EntitySetRights.All);
                }

object GetService() 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>
Stream GetReadStream() 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;
                        }
                }

Uri GetReadStreamUri() Uri GetReadStreamUri(object entity, DataServiceOperationContext operationContext)
                {
                        return null;
                }

                // 流的内容类型
string GetStreamContentType() string GetStreamContentType(object entity, DataServiceOperationContext operationContext)
                {
                        return "image/jpeg";
                }

string GetStreamETag() string GetStreamETag(object entity, DataServiceOperationContext operationContext)
                {
                        return null;
                }

                // 流的缓冲区大小
                public int StreamBufferSize
                {
                        get { return 64; }
                }

void DeleteStream() void DeleteStream(object entity, DataServiceOperationContext operationContext)
                {
                        throw new NotImplementedException();
                }

System.IO.Stream GetWriteStream() System.IO.Stream GetWriteStream(object entity, string etag, bool? checkETagForEquality, DataServiceOperationContext operationContext)
                {
                        throw new NotImplementedException();
                }

string ResolveType() 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">

        

        
        <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>
        {
static void InitializeService() 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

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

OK
[源码下载]

本文转自webabcd 51CTO博客，原文链接：http://blog.51cto.com/webabcd/341317，如需转载请自行联系原作者

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