CODEWITHSUNDEEP
c#jsonasp.net-web-apiasp.net-web-api2
Martijn
Martijn

Reputation: 24789

How to format a custom type in the json result?

I have a custom class, which basically boils down to this:

public class MyValue
{
    public MyValue(int v)
    {
        Value = v;
    }

    public int Value {get;}
}

I use this class as a property on various classes. When my API returns a class (which has a MyValue property), the json returned looks like:

"propertyOfTypeMyValue": {
    "value": 4
}

I don't want this. What I'd like is that the json returned looks like this:

"propertyOfTypeMyValue": 4

Is this possible? If so, how?

Upvotes: 1

Views: 72

Answers (1)

Brian Rogers
Brian Rogers

Reputation: 129677

Yes, it is possible to get the output you want by creating a custom JsonConverter for your MyValue class like this:

public class MyValueConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        return objectType == typeof(MyValue);
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null) 
            return null;
        if (reader.TokenType == JsonToken.Integer) 
            return new MyValue(Convert.ToInt32(reader.Value));
        throw new JsonException("Unexpected token type: " + reader.TokenType);
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        writer.WriteValue(((MyValue)value).Value);
    }
}

To use the converter, mark the MyValue class with a [JsonConverter] attribute:

[JsonConverter(typeof(MyValueConverter))]
public class MyValue
{
    public MyValue(int v)
    {
        Value = v;
    }

    public int Value { get; private set; }
}

Here is a working demo: https://dotnetfiddle.net/A4eU87

Upvotes: 1

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