.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

#region 程序集 Newtonsoft.Json, Version=4.5.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed
// E:VsGitDigitizationPlatformdllNewtonsoft.Json.dll
#endregion

namespace Newtonsoft.Json
{
    //
    // 摘要:
    //     Specifies reference loop handling options for the Newtonsoft.Json.JsonSerializer.
    public enum ReferenceLoopHandling
    {
        //
        // 摘要:
        //     Throw a Newtonsoft.Json.JsonSerializationException when a loop is encountered.
        Error = 0,
        //
        // 摘要:
        //     Ignore loop references and do not serialize.
        Ignore = 1,
        //
        // 摘要:
        //     Serialize loop references.
        Serialize = 2
    }
}

　　我们可以设置JsonSerializerSettings 

 　　　　　　　　 JsonSerializerSettings set = new JsonSerializerSettings();
                set.Formatting = Formatting.Indented;
                set.DateFormatString = "yyyy-MM-dd HH:mm:ss";
                //set.MaxDepth = 10;
                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：

using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Web;
using System.Web.Mvc;

namespace Goldwind.Framework.Web.OverrideExtension
{
    public class MyJsonResult: JsonResult
    {
        public MyJsonResult() { }
        public MyJsonResult(object Data) {
            this.Data = Data;
        }
        public MyJsonResult(object Data, JsonRequestBehavior JsonRequestBehavior = JsonRequestBehavior.DenyGet) :this(Data){
            this.JsonRequestBehavior = JsonRequestBehavior;
        }
        public MyJsonResult(object Data, string ContentType,Encoding ContentEncoding = null, JsonRequestBehavior JsonRequestBehavior = JsonRequestBehavior.DenyGet) :this(Data,JsonRequestBehavior) {
            this.ContentType = ContentType;
            if(ContentEncoding != null)
            {
                this.ContentEncoding = ContentEncoding;
            }
        }
        public override void ExecuteResult(ControllerContext context)
        {
            if(this.JsonRequestBehavior == JsonRequestBehavior.DenyGet
                && string.Compare(context.HttpContext.Request.HttpMethod,"Get",true) == 0)
            {
                throw new InvalidOperationException();
            }
            HttpResponseBase response = context.HttpContext.Response;
            response.ContentType = string.IsNullOrEmpty(this.ContentType) ?
                "application/json" : this.ContentType;
            if(this.ContentEncoding != null)
            {
                response.ContentEncoding = this.ContentEncoding;
            }
            if(null != this.Data)
            {
                JsonSerializerSettings set = new JsonSerializerSettings();
                set.Formatting = Formatting.Indented;
                set.DateFormatString = "yyyy-MM-dd HH:mm:ss";
                //set.MaxDepth = 10;
                set.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
                response.Write(JsonConvert.SerializeObject(this.Data,set));
            }
        }
    }
}