C# Json 将整数反序列化为类型实例答案

【问题标题】：C# Json deserialize integer to type instanceC# Json 将整数反序列化为类型实例
【发布时间】：2015-10-17 09:50:38
【问题描述】：

考虑下面给出的 json 字符串：

{
    "items":
    [
        { 
            ..., 
            "view_count":4,
            "answer_count":0,
            "score":0,
            "last_activity_date":1445071150
        }
    ],
    ...
}

有没有办法使用System.Runtime.Serialization.DataContractAttribute 和System.Runtime.Serialization.Json.DataContractJsonSerializer 将last_activity_date 反序列化为另一种类型的实例？

例如：1445071150 -> Date 其中Date 是

[System.Runtime.Serialization.DataContract]
public class Date
{
    [System.Runtime.Serialization.IgnoreDataMember]
    public long ElapsedSeconds { get; set; }

    [System.Runtime.Serialization.IgnoreDataMember]
    public DateTime Date { get { ... } set; }

    public Date(long seconds)
    {
        ElapsedSeconds = seconds;
        Date = ...;
    }

    public static implicit operator Date(long seconds)
    {
        return new Date(seconds);
    }

    // Other members ...
}

【问题讨论】：

我认为你应该实现IContractResolver : newtonsoft.com/json/help/html/contractresolver.htm 并使用自己的Converter。

标签： c# json deserialization datacontract

【解决方案1】：

你可以有这样的定义：

[DataContract]
public class Item
{
    [DataMember(Name = "view_count")]
    public int ViewCount { get; set; }

    [DataMember(Name = "answer_count")]
    public int AnswerCount { get; set; }

    [DataMember(Name = "score")]
    public int Score { get; set; }

    [IgnoreDataMember]
    public Date LastActivityDate { get; private set; }

    [DataMember(Name = "last_activity_date")]
    private long Date
    {
        set
        {
            LastActivityDate = value;
        }
        get
        {
            return LastActivityDate.ElapsedSeconds;
        }
    }
}

现在当 JSON 被反序列化时，Date 属性的设置器将负责设置 LastActivityDate 成员。

这是一个完整的例子：

using System;
using System.IO;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Json;
using System.Text;

[DataContract]
public class Root
{
    [DataMember(Name = "items")]
    public Item[] Items { get; set; }
}

[DataContract]
public class Item
{
    [DataMember(Name = "view_count")]
    public int ViewCount { get; set; }

    [DataMember(Name = "answer_count")]
    public int AnswerCount { get; set; }

    [DataMember(Name = "score")]
    public int Score { get; set; }

    [IgnoreDataMember]
    public Date LastActivityDate { get; private set; }

    [DataMember(Name = "last_activity_date")]
    private long Date
    {
        set
        {
            LastActivityDate = value;
        }
        get
        {
            return LastActivityDate.ElapsedSeconds;
        }
    }
}

[DataContract]
public class Date
{
    [IgnoreDataMember]
    public long ElapsedSeconds { get; set; }

    public Date(long seconds)
    {
        ElapsedSeconds = seconds;
    }

    public static implicit operator Date(long seconds)
    {
        return new Date(seconds);
    }
}

static class Program
{
    static void Main()
    {
        string json = 
            @"{
                ""items"":
                [
                    { 
                        ""view_count"":4,
                        ""answer_count"":0,
                        ""score"":0,
                        ""last_activity_date"":1445071150
                    }
                ]
            }";

        var serializer = new DataContractJsonSerializer(typeof(Root));
        using (var stream = new MemoryStream(Encoding.UTF8.GetBytes(json)))
        {
            var root = (Root)serializer.ReadObject(stream);
            Console.WriteLine(root.Items[0].LastActivityDate.ElapsedSeconds);
        }
    }
}

【讨论】：