序列化字典<,>作为 Json.NET 中的数组 [英] Serialize Dictionary<,> as array in Json.NET

问题描述

如何使 Json.NET 序列化程序将 IDictionary<,> 实例序列化为具有键/值属性的对象数组?默认情况下，它将 Key 的值序列化为 JSON 对象的属性名称.

How can I make Json.NET serializer to serialize IDictionary<,> instance into array of objects with key/value properties? By default it serializes the value of Key into JSON object's property name.

基本上我需要这样的东西:

Basically I need something like this:

[{"key":"some key","value":1},{"key":"another key","value":5}]

代替:

{{"some key":1},{"another key":5}}

我尝试将 KeyValuePairConverter 添加到序列化程序设置，但没有效果.(我发现对于 IDictionary<> 的类型，此转换器被忽略，但我无法轻易更改对象的类型，因为它们是从其他库接收的，因此从 IDictionary<> 到 ICollection<KeyValuePair<>> 不适合我.)

I tried to add KeyValuePairConverter to serializer settings but it has no effect. (I found this converter is ignored for type of IDictionary<> but I cannot easily change the type of my objects as they are received from other libraries, so changing from IDictionary<> to ICollection<KeyValuePair<>> is not option for me.)

推荐答案

我能够让这个转换器工作.

I was able to get this converter to work.

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

public class CustomDictionaryConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        return (typeof(IDictionary).IsAssignableFrom(objectType) || 
                TypeImplementsGenericInterface(objectType, typeof(IDictionary<,>)));
    }

    private static bool TypeImplementsGenericInterface(Type concreteType, Type interfaceType)
    {
        return concreteType.GetInterfaces()
               .Any(i => i.IsGenericType && i.GetGenericTypeDefinition() == interfaceType);
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        Type type = value.GetType();
        IEnumerable keys = (IEnumerable)type.GetProperty("Keys").GetValue(value, null);
        IEnumerable values = (IEnumerable)type.GetProperty("Values").GetValue(value, null);
        IEnumerator valueEnumerator = values.GetEnumerator();

        writer.WriteStartArray();
        foreach (object key in keys)
        {
            valueEnumerator.MoveNext();

            writer.WriteStartObject();
            writer.WritePropertyName("key");
            writer.WriteValue(key);
            writer.WritePropertyName("value");
            serializer.Serialize(writer, valueEnumerator.Current);
            writer.WriteEndObject();
        }
        writer.WriteEndArray();
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        throw new NotImplementedException();
    }
}

以下是使用转换器的示例:

Here is an example of using the converter:

IDictionary<string, int> dict = new Dictionary<string, int>();
dict.Add("some key", 1);
dict.Add("another key", 5);

string json = JsonConvert.SerializeObject(dict, new CustomDictionaryConverter());
Console.WriteLine(json);

这是上面的输出:

[{"key":"some key","value":1},{"key":"another key","value":5}]

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