c# - Web API: Configure JSON serializer settings on action or controller level

Question

Overriding the default JSON serializer settings for web API on application level has been covered in a lot of SO threads. But how can I configure its settings on action level? For example, I might want to serialize using camelcase properties in one of my actions, but not in the others.

Answer 1

Option 1 (quickest)

At action level you may always use a custom JsonSerializerSettings instance while using Json method:

public class MyController : ApiController
{
    public IHttpActionResult Get()
    {
        var settings = new JsonSerializerSettings
        {
            ContractResolver = new CamelCasePropertyNamesContractResolver()
        };
        var model = new MyModel();
        return Json(model, settings);
    }
}

Option 2 (controller level)

You may create a new IControllerConfiguration attribute which customizes the JsonFormatter:

public class CustomJsonAttribute : Attribute, IControllerConfiguration 
{
    public void Initialize(HttpControllerSettings controllerSettings, HttpControllerDescriptor controllerDescriptor)
    {
        var formatter = controllerSettings.Formatters.JsonFormatter;

        controllerSettings.Formatters.Remove(formatter);

        formatter = new JsonMediaTypeFormatter
        {
            SerializerSettings =
            {
                ContractResolver = new CamelCasePropertyNamesContractResolver()
            }
        };

        controllerSettings.Formatters.Insert(0, formatter);
    }
}

[CustomJson]
public class MyController : ApiController
{
    public IHttpActionResult Get()
    {
        var model = new MyModel();
        return Ok(model);
    }
}