WebApi custom JsonConverter not called - json

Question

I implemented a custom JsonConverter for Guids.
If I declare it on the properties (of type Guid) of the class serialized like so
[JsonConverter(typeof(JsonGuidConverter))]
then it gets called and works fine.
However, I'd like to use it "automatically", without needed the attributes, so I do this:
var formatters = GlobalConfiguration.Configuration.Formatters;
var jsonFormatter = formatters.JsonFormatter;
jsonFormatter.SerializerSettings.Converters.Add(new JsonGuidConverter());
Unfortunately this results in my converter never getting called. I'm using WebApi 2.1 in a MVC 5.1 project.
Any ideas?
Edit: here is the converter code
public class JsonGuidConverter : JsonConverter
{
public override bool CanRead
{
get
{
// We only need the converter for writing Guids without dashes, for reading the default mechanism is fine
return false;
}
}
public override bool CanWrite
{
get
{
return true;
}
}
public override bool CanConvert(Type objectType)
{
return objectType == typeof(Guid) || objectType == typeof(Guid?);
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, Newtonsoft.Json.JsonSerializer serializer)
{
// We declared above CanRead false so the default serialization will be used
throw new NotImplementedException();
}
public override void WriteJson(JsonWriter writer, object value, Newtonsoft.Json.JsonSerializer serializer)
{
if (value == null || Guid.Empty.Equals(value))
{
writer.WriteValue(string.Empty);
}
else
{
writer.WriteValue(((Guid)value).ToStringNoDashes());
}
}
}
Additional note, not even the CanRead/CanWrite properties and CanConvert method are called when trying to use it by adding it to the converters collection.
Maybe it has something to do with how I return data from the webapi controller?
public async Task<IHttpActionResult> GetSettings()
{
...
return Json(something);
}

Answer 1

Since your are using formatters, do not use Json(something) when returning from action, but rather use Content(something) in this case. The Content helper will honor the formatters' settings.
I agree that Json helper is confusing here and something which I wished we never included in our product.