.Net MVC5异步请求Entity Framework 无限循环解决方法

.Net MVC5异步请求Entity Framework 无限循环解决方法

　　Entity Framework 存在一对多、多对多之间的关系，相互依赖，在返回JSON数据时往往会出现相互引用造成的无限循环问题，对于第三方提供的json序列还通过特性、序列化配置可以解决掉无限循环的问题，因此我们可以利用第三方库解决掉MVC返回JSON无限循环的问题。

　　我们可以利用Newtonsoft.Json 的JsonSerializerSettings类进行序列化的设置

　　

　　对于ReferenceLoopHandling枚举类型

 1 #region 程序集 Newtonsoft.Json, Version=4.5.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed
 2 // E:\VsGit\DigitizationPlatform\dll\Newtonsoft.Json.dll
 3 #endregion
 4 
 5 namespace Newtonsoft.Json
 6 {
 7     //
 8     // 摘要:
 9     //     Specifies reference loop handling options for the Newtonsoft.Json.JsonSerializer.
10     public enum ReferenceLoopHandling
11     {
12         //
13         // 摘要:
14         //     Throw a Newtonsoft.Json.JsonSerializationException when a loop is encountered.
15         Error = 0,
16         //
17         // 摘要:
18         //     Ignore loop references and do not serialize.
19         Ignore = 1,
20         //
21         // 摘要:
22         //     Serialize loop references.
23         Serialize = 2
24     }
25 }

　　我们可以设置JsonSerializerSettings 

1  　　　　　　　　 JsonSerializerSettings set = new JsonSerializerSettings();
2                 set.Formatting = Formatting.Indented;
3                 set.DateFormatString = "yyyy-MM-dd HH:mm:ss";
4                 //set.MaxDepth = 10;
5                 set.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;

　　这样我们便可以解决JsonResult返回JSON无限循环问题了

重写MVC -> JsonResult：

 1 using Newtonsoft.Json;
 2 using System;
 3 using System.Collections.Generic;
 4 using System.Linq;
 5 using System.Text;
 6 using System.Threading.Tasks;
 7 using System.Web;
 8 using System.Web.Mvc;
 9 
10 namespace Goldwind.Framework.Web.OverrideExtension
11 {
12     public class MyJsonResult: JsonResult
13     {
14         public MyJsonResult() { }
15         public MyJsonResult(object Data) {
16             this.Data = Data;
17         }
18         public MyJsonResult(object Data, JsonRequestBehavior JsonRequestBehavior = JsonRequestBehavior.DenyGet) :this(Data){
19             this.JsonRequestBehavior = JsonRequestBehavior;
20         }
21         public MyJsonResult(object Data, string ContentType,Encoding ContentEncoding = null, JsonRequestBehavior JsonRequestBehavior = JsonRequestBehavior.DenyGet) :this(Data,JsonRequestBehavior) {
22             this.ContentType = ContentType;
23             if(ContentEncoding != null)
24             {
25                 this.ContentEncoding = ContentEncoding;
26             }
27         }
28         public override void ExecuteResult(ControllerContext context)
29         {
30             if(this.JsonRequestBehavior == JsonRequestBehavior.DenyGet
31                 && string.Compare(context.HttpContext.Request.HttpMethod,"Get",true) == 0)
32             {
33                 throw new InvalidOperationException();
34             }
35             HttpResponseBase response = context.HttpContext.Response;
36             response.ContentType = string.IsNullOrEmpty(this.ContentType) ?
37                 "application/json" : this.ContentType;
38             if(this.ContentEncoding != null)
39             {
40                 response.ContentEncoding = this.ContentEncoding;
41             }
42             if(null != this.Data)
43             {
44                 JsonSerializerSettings set = new JsonSerializerSettings();
45                 set.Formatting = Formatting.Indented;
46                 set.DateFormatString = "yyyy-MM-dd HH:mm:ss";
47                 //set.MaxDepth = 10;
48                 set.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
49                 response.Write(JsonConvert.SerializeObject(this.Data,set));
50             }
51         }
52     }
53 }