Serializing Dictionary to array of "name": "value"

Question

I have this simple model in an ASP.NET WebAPI 2 application:

public class Model {
    public int ID { get; set; }
    public Dictionary<string, string> Dic { get; set; }
}

When it gets serialized, the output is:

{
    "ID": 0,
    "Dic": {
        "name1": "value1",
        "name2": "value2"
    }
}

I searched the problem, but it seems most people need this serialization:

{
    "ID": 0,
    "Dic": [{
        "Key": "name1",
        "Value": "value1"
    }]
}

And all solutions out there are resolving to that kind of serialization. But what I'm looking for is to serialize the dictionary into this format:

{
    "ID": 0,
    "Dic": [{
        "name1": "value1"
    }, {
        "name2": "value2"
    }]
}

In other words, I want to serialize it into an array of objects containing one "name1": "value1" pair each. Is there any way to do that? Or I should be looking for another type?

Array in json can't have key. You should use object (hash) instead. — Niyoko, Oct 26 '16 at 08:29
Sorry man, your json is not valid. You can check it on any online json validator — Dmitresky, Oct 26 '16 at 08:50

score 1 · Accepted Answer · answered Oct 26 '16 at 15:00

You can use a custom JsonConverter to get the JSON you're looking for. Here is the code you would need for the converter:

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

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        IDictionary dict = (IDictionary)value;
        JArray array = new JArray();
        foreach (DictionaryEntry kvp in dict)
        {
            JObject obj = new JObject();
            obj.Add(kvp.Key.ToString(), kvp.Value != null ? JToken.FromObject(kvp.Value, serializer) : new JValue((string)null));
            array.Add(obj);
        }
        array.WriteTo(writer);
    }

    public override bool CanRead
    {
        get { return false; }
    }

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

To use the converter, mark the dictionary in your model class with a [JsonConverter] attribute like this:

public class Model 
{
    public int ID { get; set; }
    [JsonConverter(typeof(CustomDictionaryConverter))]
    public Dictionary<string, string> Dic { get; set; }
}

Demo fiddle: https://dotnetfiddle.net/320LmU

Serializing Dictionary to array of "name": "value"

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