【因】

　　　WebAPI的Controller中，一般都是下面四种方法：

　　对应于数据操作是我们通常所说的CRUD.

　　C对应post,R对应Get，U对应Put，D对应Delete。

　　直接模仿VS 2012 WebAPI项目模板中的CRUD方法，R传回的是要查的值，CUD都是空，这样虽然也满足逻辑，

　　但是一旦出错，没有有效的错误处理机制，如上一节Controller中的方法,虽然也可以使用,但不适合作为商用项目中的标准方法.

　　所以在此总结出较标准的CRUD方法模板，以供参考。

 

【果】

　　改编自第一节中的CRUD方法

　　1.Read

　　1)GET  api/courses/id

　　不同于以前返回的是要查找的对象,现在返回的是HttpResponseMessage对象，其中可以包含要返回的对象值，一旦出错，会有恰当的

　　错误代码及信息返回。

1 // GET api/courses/id 2         public HttpResponseMessage Get(int id) 3         {  4             HttpResponseMessage msg=null; 5             var ret=(from c in courses 6                      where c.id==id 7                      select c).FirstOrDefault(); 8             //todo: if null- should return 404 9             if (ret == null)10             {11                 msg = Request.CreateErrorResponse(HttpStatusCode.NotFound, "Course not found");12             }13             else14             {15                 msg = Request.CreateResponse
     
      (HttpStatusCode.OK, ret);16             }17             return msg;18         }
     

　　

     2.Create

 　　Post   api/courses/

1 // Post api/courses 2         public HttpResponseMessage Post([FromBody]course c) 3         { 4             c.id = courses.Count; 5             courses.Add(c); 6             //TODO:: should return a 201 with a location head 7             var msg = Request.CreateResponse(HttpStatusCode.Created); 8             msg.Headers.Location = new Uri(Request.RequestUri + c.id.ToString()); 9             return msg;10         }

    

　　3.Update

1  // Put api/courses/id 2         public HttpResponseMessage Put(int id, [FromBody]course c) 3         { 4             HttpResponseMessage msg = null; 5             var ret = (from v in courses 6                        where v.id == c.id 7                        select v).FirstOrDefault(); 8             if (ret == null) 9             {10                 msg = Request.CreateErrorResponse(HttpStatusCode.NotFound, "Course not found");11             }12             else13             {14                 ret.title = c.title;15                 msg = Request.CreateResponse
     
      (HttpStatusCode.Accepted, ret);16                 msg.Headers.Location = new Uri(Request.RequestUri + c.id.ToString());17             }18             return msg;19         }
     

    

　　 4.Delete

1  // Delete api/courses/id 2         public HttpResponseMessage Delete(int id) 3         { 4             HttpResponseMessage msg = null; 5             var ret = (from c in courses 6                        where c.id == id 7                        select c).FirstOrDefault(); 8              9             if (ret == null)10             {11                 msg = Request.CreateErrorResponse(HttpStatusCode.NotFound, "Course not found");12             }13             else14             {15                 courses.Remove(ret);16                 msg = Request.CreateResponse
     
      (HttpStatusCode.Gone, ret);17             }18             return msg;19         }