在ASP.NET Web API中使用OData

2019-12-21 23:08 来源:未知

一.什么是OData OData是一个开放的数据协议(Open Data Protocol)
在ASP.NET Web API中,
对于CRUD(create, read, update, and delete)应用比传统WebAPI增加了很大的灵活性
只要正确使用相关的协议,可以在同等情况下
对一个CRUD应用可以节约很多开发时间,从而提高开发效率

二.怎么搭建

做一个简单的订单查询示例
我们使用Code First模式创建两个实体对象Product(产品),Supplier(供应商)
1.新建一个ASP.NET Empty项目,选择上使用Web API,如下图
图片 1
2.使用NuGet引用OData和EntityFramework程序集
图片 2
3.在Models文件夹中增加Product(产品),Supplier(供应商)两个实体

public class Product    {        public int Id { get; set; }        public string Name { get; set; }        public decimal Price { get; set; }        public string Category { get; set; }        [ForeignKey("Supplier")]        public int? SupplierId { get; set; }        public virtual Supplier Supplier { get; set; }    }public class Supplier    {        public int Id { get; set; }        public string Name { get; set; }        public ICollection<Product> Products { get; set; }    }

4.增加ProductContext数据库上下文对象,并且在web.config中配置好ConnectionString

public class ProductContext : DbContext    {        public ProductContext()            : base("Demo")        { }        public DbSet<Product> Products { get; set; }        public DbSet<Supplier> Suppliers { get; set; }    }

 

<connectionStrings>        <add name="Demo" connectionString="Data Source=(localdb)v11.0;         Initial Catalog=Demo; Integrated Security=True; MultipleActiveResultSets=True;         AttachDbFilename=|DataDirectory|Demo.mdf"      providerName="System.Data.SqlClient" />    </connectionStrings>

5.生成数据库
我们启动程序包管理控制台,运行如下3个命令,
把我们Code First生成的实体生成到数据库
PM> Enable-Migrations
PM> Add-Migration FirstInit
PM> Update-Database
然后我们可以在服务器资源管理器中看到我们生成的数据库表,如下图
图片 3图片 4
6.接下来我们在WebApiConfig中注册我们的OData路由

using Demo2.Models;using System.Web.OData.Builder;using System.Web.OData.Extensions;namespace Demo2{    public static class WebApiConfig    {        public static void Register(HttpConfiguration config)        {            ODataModelBuilder builder = new ODataConventionModelBuilder();            builder.EntitySet<Product>("Products");            builder.EntitySet<Supplier>("Suppliers");            config.MapODataServiceRoute("ODataRoute", null, builder.GetEdmModel());        }    }}

7.接下来我们分别为Product和Supplier新建ODataController,
图片 5
图片 6
我们在上图中我们选择好模型类和数据上下文,
并重复上面两步为Supplier实体也生成对应的ODataController
注意:由于VS2013的OData模板中OData V3版本的模板,
引用的名称空间要从V3
using System.Web.Http;
using System.Web.Http.ModelBinding;
using System.Web.Http.OData;
using System.Web.Http.OData.Routing;
修改为V4
using System.Web.Http;
using System.Web.OData;

到此,我们的OData示例程序已经搭建完成,我们在浏览器里打开这个项目的时候
会出现如下

{  "@odata.context":"http://localhost:8914/$metadata","value":[    {      "name":"Products","kind":"EntitySet","url":"Products"    },{      "name":"Suppliers","kind":"EntitySet","url":"Suppliers"    }  ]}

表示已经搭建成功了

三.怎么使用 由于没有测试数据,我们开始先在数据库表里为Products和Suppliers增加一些测试数据
图片 7
图片 8
接下来我们看看一些简单的使用示例
在自动生成的ProductsController和SuppliersController中
已经为我们生成了如下一些Action
图片 9图片 10
所以对于一些增加,修改,删除,更新我就不做过多示例,
这些都是和WebAPI没有什么太多区别,
我主要示例的是查询的使用,不得不说OData已经为我们把查询功能全做完了
示例1:列出所有Product
URL:

{

"@odata.context":"http://localhost:8914/$metadata#Products","value":[

{

"Id":1,"Name":"Products1","Price":100.00,"Category":"Test","SupplierId":1

},{

"Id":2,"Name":"Products2","Price":200.00,"Category":"Test","SupplierId":1

},{

"Id":3,"Name":"Products3","Price":300.00,"Category":"Test","SupplierId":1

},{

"Id":4,"Name":"Products4","Price":400.00,"Category":"P1","SupplierId":2

},{

"Id":5,"Name":"Products5","Price":500.00,"Category":"P1","SupplierId":2

},{

"Id":6,"Name":"Products6","Price":600.00,"Category":"P1","SupplierId":2

},{

"Id":7,"Name":"Products7","Price":700.00,"Category":"P1","SupplierId":2

},{

"Id":8,"Name":"Products8","Price":800.00,"Category":"Test","SupplierId":3

},{

"Id":9,"Name":"Products9","Price":900.00,"Category":"P1","SupplierId":3

}

]

}

示例2,查询单个Products
URL:) 其中(1)为Id

{  "@odata.context":"http://localhost:8914/$metadata#Products/$entity","Id":1,"Name":"Products1","Price":100.00,"Category":"Test","SupplierId":1}

示例3,查询Products,只列出Name,Price例
URL:

{  "@odata.context":"http://localhost:8914/$metadata#Products(Name,Price)","value":[    {      "Name":"Products1","Price":100.00    },{      "Name":"Products2","Price":200.00    },{      "Name":"Products3","Price":300.00    },{      "Name":"Products4","Price":400.00    },{      "Name":"Products5","Price":500.00    },{      "Name":"Products6","Price":600.00    },{      "Name":"Products7","Price":700.00    },{      "Name":"Products8","Price":800.00    },{      "Name":"Products9","Price":900.00    }  ]}

示例5:只列出ID为1的Products,只显示列Name,Price

URL:

{  "@odata.context":"http://localhost:8914/$metadata#Products(Name,Price)/$entity","Name":"Products1","Price":100.00}

示例6:列出Products(只有列Name,Price),包括Supplier
URL:

{  "@odata.context":"http://localhost:8914/$metadata#Products(Name,Price,Supplier)","value":[    {      "Name":"Products1","Price":100.00,"Supplier":{        "Id":1,"Name":"Supplier1"      }    },{      "Name":"Products2","Price":200.00,"Supplier":{        "Id":1,"Name":"Supplier1"      }    },{      "Name":"Products3","Price":300.00,"Supplier":{        "Id":1,"Name":"Supplier1"      }    },{      "Name":"Products4","Price":400.00,"Supplier":{        "Id":2,"Name":"Supplier2"      }    },{      "Name":"Products5","Price":500.00,"Supplier":{        "Id":2,"Name":"Supplier2"      }    },{      "Name":"Products6","Price":600.00,"Supplier":{        "Id":2,"Name":"Supplier2"      }    },{      "Name":"Products7","Price":700.00,"Supplier":{        "Id":2,"Name":"Supplier2"      }    },{      "Name":"Products8","Price":800.00,"Supplier":{        "Id":3,"Name":"Supplier3"      }    },{      "Name":"Products9","Price":900.00,"Supplier":{        "Id":3,"Name":"Supplier3"      }    }  ]}

示例7:过滤Products,只显示分类为Test的数据
URL: eq ’Test‘

{  "@odata.context":"http://localhost:8914/$metadata#Products","value":[    {      "Id":1,"Name":"Products1","Price":100.00,"Category":"Test","SupplierId":1    },{      "Id":2,"Name":"Products2","Price":200.00,"Category":"Test","SupplierId":1    },{      "Id":3,"Name":"Products3","Price":300.00,"Category":"Test","SupplierId":1    },{      "Id":8,"Name":"Products8","Price":800.00,"Category":"Test","SupplierId":3    }  ]}

示例8:过滤Products,只显示分类为Test的数据,并排序
URL: eq ’Test‘&$orderby=Price desc

{  "@odata.context":"http://localhost:8914/$metadata#Products","value":[    {      "Id":8,"Name":"Products8","Price":800.00,"Category":"Test","SupplierId":3    },{      "Id":3,"Name":"Products3","Price":300.00,"Category":"Test","SupplierId":1    },{      "Id":2,"Name":"Products2","Price":200.00,"Category":"Test","SupplierId":1    },{      "Id":1,"Name":"Products1","Price":100.00,"Category":"Test","SupplierId":1    }  ]}

下面是$filter的其它的使用方式
1.  eq 'Test'
过滤Category=Test
2. lt 10
过滤Price小于10
3。 ge 5 and Price le 15
过滤5<=Price>=15
5,还可以使用数据库函数如:
$filter=substringof('zz',Name)
$filter=year(ReleaseDate) gt 2005

关于排序
$orderby=Price
$orderby=Price desc
$orderby=Category,Price desc

还有一些过滤器如
$skip,$top,$inlinecount等等
所以OData基本上实现我们们想要查询的相关方法
对于CURD程序的查询来说大大提高开发效率

四: 相关引用资源

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