EF 序列化实体为Json时的循环引用问题(不用自己写实体,不用匿名类型,不用EF的上下文属性)

using Newtonsoft.Json;
using Newtonsoft.Json.Converters;
using Newtonsoft.Json.Serialization;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Web;

namespace AceepSystem.Models.Help
{
    public class JsonForEF : DefaultContractResolver
    {
        string[] props = null;

        bool retain;

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="props">传入的属性数组</param>
        /// <param name="retain">true:表示props是需要保留的字段  false：表示props是要排除的字段</param>
        public JsonForEF(string[] props, bool retain = true)
        {
            //指定要序列化属性的清单
            this.props = props;

            this.retain = retain;
        }

        protected override IList<JsonProperty> CreateProperties(Type type,

        MemberSerialization memberSerialization)
        {
            IList<JsonProperty> list =
            base.CreateProperties(type, memberSerialization);
            //只保留清单有列出的属性
            return list.Where(p =>
            {
                if (retain)
                {
                    return props.Contains(p.PropertyName);
                }
                else
                {
                    return !props.Contains(p.PropertyName);
                }
            }).ToList();
        }
        public static string[] GetVirtualList<T>()
        {
            var stringType = typeof(T);
            var props = stringType.GetProperties();
            List<string> test = new List<string>();
            foreach (var prop in props)
            {
                if (prop.GetAccessors()[0].IsVirtual)
                {
                    test.Add(prop.Name);
                }
            }
            return test.ToArray();
        }
        public static JsonSerializerSettings GetJsonConfig<T>()
        {

            JsonSerializerSettings jsetting = new JsonSerializerSettings();//过滤掉ef中的导航属性,无残留...
            jsetting.ContractResolver = new JsonForEF(
            JsonForEF.GetVirtualList<T>()//泛型方法传入当前要序列化的类型
            , false);//false为要排除的属性,true为要保留的属性(第一个参数为string[])
            jsetting.Converters.Add(new MyDateTimeConvertor());
            return jsetting;
        }
        public class MyDateTimeConvertor : DateTimeConverterBase
        {
            public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
            {
                return DateTime.Parse(reader.Value.ToString());
            }

            public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
            {
                writer.WriteValue(((DateTime)value).ToString("yyyy/MM/dd HH:mm"));
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Web;

namespace AceepSystem.Models.Help
{
    public static class Virtual_Help
    {
      
        public static bool? IsVirtual(this PropertyInfo self)
        {
            if (self == null)
                throw new ArgumentNullException("self");

            bool? found = null;

            foreach (MethodInfo method in self.GetAccessors())
            {
                if (found.HasValue)
                {
                    if (found.Value != method.IsVirtual)
                        return null;
                }
                else
                {
                    found = method.IsVirtual;
                }
            }

            return found;
        }
       
    }
}