the_void the_void - 7 months ago 45
JSON Question

Skip Serializing the the Property Name for a JSON Object using Newtonsoft.Json

I have the below simple class

class MyType {
string JsonData { get; set;}

string OtherProperty { get; set; }
}


where
JsonData
contains formatted JSON that I want to plug into the serialized class output:

"Prop1":"Value1",
"Prop2":"Value2",
"Prop3":"Value3"


and I want to have it serialized as

{
<JsonData>,
"OtherProperty": ""
}


I have tried using a custom
JsonConverter
for that field, but I cannot find a way to remove the serialization of the property name:

{
"JsonData": <JsonData>,
"OtherProperty": ""
}


So basically I just need to have
"JsonData":
removed from the output (preferably without using
string.Replace()
)

Answer Source

You can do this with a custom JsonConverter, but the converter has to be made to handle the whole MyType class as opposed to just the JsonData property. As you've seen, there is no way to omit the property name from within a converter that handles just the property.

Here is how I might write the converter:

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

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        MyType mt = (MyType)value;
        JObject jo = new JObject();

        if (!string.IsNullOrWhiteSpace(mt.JsonData))
        {
            // JsonData is assumed to contain pre-formatted, comma-separated, JSON properties
            jo.Add(JObject.Parse("{" + mt.JsonData + "}").Properties());
        }

        foreach (PropertyInfo prop in typeof(MyType).GetProperties()
                 .Where(p => p.CanRead && p.Name != "JsonData"))
        {
            object val = prop.GetValue(mt, null);
            jo.Add(prop.Name, val != null ? JToken.FromObject(val, serializer) : JValue.CreateNull());
        }

        jo.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, just annotate your class with a [JsonConverter] attribute like this:

[JsonConverter(typeof(MyTypeConverter))]
class MyType
{
    ...
}

Demo fiddle: https://dotnetfiddle.net/bu0NgC


Having presented the above, I should point out that this might not be the best solution, depending on where the pre-formatted JSON properties are coming from. If they are coming from a third party out of your control, then the design you have along with the converter is probably adequate. However, if you are creating the pre-formatted JSON properties yourself somewhere along the line as a way of having dynamic properties in your MyType class, then there is definitely a better way to do it.

Instead of using a string, you can declare JsonData as a Dictionary<string, object> and mark it with the special [JsonExtensionData] attribute:

class MyType 
{
    public MyType()
    {
        JsonData = new Dictionary<string, object>();
    }

    [JsonExtensionData]
    public Dictionary<string, object> JsonData { get; set;}

    public string OtherProperty { get; set; }
}

Then, just add your dynamic properties to the dictionary as key-value pairs:

MyType mt = new MyType();
mt.JsonData.Add("Prop1", "Value1");
...

When you serialize MyType, the dictionary KVPs will be automatically added as properties of the JSON object just like OtherProperty. No converter needed!

Fiddle: https://dotnetfiddle.net/f8gCVA