WebApi学习笔记07：使用webapi核心文件模板 --创建OData端点

1.Web项目

1.1概述

前面介绍的EF访问和操作数据库，要OUT了（当然不是啦），这章使用OData(开源数据协议)……

1.2创建项目

在“解决方案资源管理器”中右键，添加-》新建解决方案文件夹，命名为：OData

右键“OData”逻辑文件夹，添加-》新建项目：

1.3安装OData框架

1.4添加模型

在Models文件夹下，添加Product.cs，其代码：

namespace ProductService.Models
{
    public class Product
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public decimal Price { get; set; }
        public string Category { get; set; }
    }
}

1.5安装EF

1.6添加上下文类

在Models文件夹下，添加EFContext.cs，其代码：

using System.Data.Entity;

namespace ProductService.Models
{
    public class EFContext : DbContext
    {
        public EFContext()
            : base("name=ProductContext")
        {
        }
        public DbSet<Product> Products { get; set; }
    }
}

1.7连接字符串

在Web.config里<configuration>下，添加：

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

1.8配置端点
修改App_Start\WebApiConfig.cs，其代码：

using ProductService.Models;
using System.Web.Http;
using System.Web.OData.Builder;
using System.Web.OData.Extensions;

namespace ProductService
{
    public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            // Web API 配置和服务

            //创建实体数据模型 (EDM)
            ODataModelBuilder builder = new ODataConventionModelBuilder();
            builder.EntitySet<Product>("Products");

            //添加路由
            config.MapODataServiceRoute(
                routeName: "ODataRoute",
                routePrefix: null,
                model: builder.GetEdmModel());

            // Web API 路由
            //config.MapHttpAttributeRoutes();

            //config.Routes.MapHttpRoute(
            //    name: "DefaultApi",
            //    routeTemplate: "api/{controller}/{id}",
            //    defaults: new { id = RouteParameter.Optional }
            //);
        }
    }
}

1.9添加控制器
在Controllers文件夹下，添加ProductsController.cs，其代码：

using ProductService.Models;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;
using System.Linq;
using System.Net;
using System.Threading.Tasks;
using System.Web.Http;
using System.Web.OData;

namespace ProductService.Controllers
{
    public class ProductsController : ODataController
    {
        EFContext db = new EFContext();

        [EnableQuery]
        public IQueryable<Product> Get()
        {
            return db.Products;
        }
        [EnableQuery]
        public SingleResult<Product> Get([FromODataUri] int key)
        {
            IQueryable<Product> result = db.Products.Where(p => p.Id == key);
            return SingleResult.Create(result);
        }

        public async Task<IHttpActionResult> Post(Product product)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }
            db.Products.Add(product);
            await db.SaveChangesAsync();
            return Created(product);
        }

        public async Task<IHttpActionResult> Patch([FromODataUri] int key, Delta<Product> product)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }
            var entity = await db.Products.FindAsync(key);
            if (entity == null)
            {
                return NotFound();
            }
            product.Patch(entity);
            try
            {
                await db.SaveChangesAsync();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!ProductExists(key))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }
            return Updated(entity);
        }
        public async Task<IHttpActionResult> Put([FromODataUri] int key, Product update)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }
            if (key != update.Id)
            {
                return BadRequest();
            }
            db.Entry(update).State = EntityState.Modified;
            try
            {
                await db.SaveChangesAsync();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!ProductExists(key))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }
            return Updated(update);
        }

        public async Task<IHttpActionResult> Delete([FromODataUri] int key)
        {
            var product = await db.Products.FindAsync(key);
            if (product == null)
            {
                return NotFound();
            }
            db.Products.Remove(product);
            await db.SaveChangesAsync();
            return StatusCode(HttpStatusCode.NoContent);
        }

        private bool ProductExists(int key)
        {
            return db.Products.Any(p => p.Id == key);
        }
        protected override void Dispose(bool disposing)
        {
            db.Dispose();
            base.Dispose(disposing);
        }
    }
}

1.10运行