Question

当我尝试使用json.net将对象转换为json时，我收到错误。

错误：

  Unable to cast object of type 'System.Collections.Generic.List`1[System.Int32]' to type
 'MyNamespace.Domain.Entity'.

要序列化的类：

[Serializable]
public class Business:Entity
    {
        public virtual string TemplateName { get; set; }

        public virtual CalculationBasis CalculationBasis { get; set; }

        public virtual PeriodSelectionType PeriodSelectionType { get; set; }

        public virtual DateTime PeriodEndDate { get; set; }

        public virtual IEnumerable<int> mainKeys { get; set; }
  }

序列化代码：

JsonSerializerSettings settings = new JsonSerializerSettings();
    settings.NullValueHandling = NullValueHandling.Ignore;
    settings.DateFormatHandling = DateFormatHandling.MicrosoftDateFormat;
    var strJson = JsonConvert.SerializeObject( ObjectOfBusiness, settings);

反序列化代码：

JsonConvert.DeserializeObject<Business>(ObjectOfBusiness, settings);

当我在IEnumerable<int> mainKeys

中有值时，我只会收到此错误

注意：mainKeys是List<int>

看起来错误是因为它的父类“Entity”，类是这样的：

  [Serializable]
    public abstract class Entity
    {
        public Entity()
        {
        }

        public Entity(int id)
        {
            this.Id = id;
        }

        public virtual int Id { get; set; }

        public override bool Equals(object obj)
        {
            Entity other = (Entity)obj;
            return this.Id == other.Id;
        }

        public override int GetHashCode()
        {
            return this.Id.GetHashCode();
        }
    }

不知道为什么json.net试图将IEnumerable转换为“entity”类型（其父类）..

我无法删除实体（父类），因为它已在很多地方使用过。

请建议。

由于

Answer 1

终于找到了解决方案。问题是因为override bool Equals(object obj)方法中的代码很差。正确的代码是：

  public override bool Equals(object obj)
        {
            if (obj is Entity)
            {
                Entity other = (Entity) obj;
                return this.Id == other.Id;
            }
            else
            {
                return false;
            }
        }

http://json.codeplex.com/workitem/16554

Answer 2

这不是一个真正的答案 - 这是“这很好”：

using Newtonsoft.Json;
using System;
using System.Collections.Generic;
public class Entity { }
public class CalculationBasis { }
public class PeriodSelectionType { }
[Serializable]
public class Business : Entity
{
    public virtual string TemplateName { get; set; }
    public virtual CalculationBasis CalculationBasis { get; set; }
    public virtual PeriodSelectionType PeriodSelectionType { get; set; }
    public virtual DateTime PeriodEndDate { get; set; }
    public virtual IEnumerable<int> mainKeys { get; set; }
}
class program
{
    static void Main()
    {
        JsonSerializerSettings settings = new JsonSerializerSettings();
        settings.NullValueHandling = NullValueHandling.Ignore;
        settings.DateFormatHandling = DateFormatHandling.MicrosoftDateFormat;

        var ObjectOfBusiness = new Business
        {
            TemplateName = "abc",
            CalculationBasis = new CalculationBasis(),
            PeriodSelectionType = new PeriodSelectionType(),
            PeriodEndDate = new DateTime(),
            mainKeys = new int[] { 1, 2, 3, 4, 5 }
        };
        var strJson = JsonConvert.SerializeObject(ObjectOfBusiness, settings);
        //...
        var obj = JsonConvert.DeserializeObject<Business>(strJson, settings);
        // ^^^^ all good
    }
}

所以：如果你能展示一个失败的案例，或者给我们提供更多线索，那将是非常好的。有关信息，上面的JSON是：

{"TemplateName":"abc","CalculationBasis":{},"PeriodSelectionType":{},"PeriodEndDate":"\/Date(-62135596800000)\/","mainKeys":[1,2,3,4,5]}

使用JsonConvert.SerializeObject时可枚举的错误

2 个答案: