How to return JSON in an ApiController for a single method?

Question

Currently, my ApiControllers are returning XML as a response, but for a single method, I want to return JSON. i.e. I can't make a global change to force responses as JSON.

public class CarController : ApiController {       [System.Web.Mvc.Route("api/Player/videos")]     public HttpResponseMessage GetVideoMappings()     {         var model = new MyCarModel();             return model;     } } 

I tried doing this, but can't seem to convert my model to a JSON string correctly:

var jsonString = Json(model).ToString();     var response = this.Request.CreateResponse(HttpStatusCode.OK); response.Content = new StringContent(jsonString, Encoding.UTF8, "application/json"); return response; 

Answer 1

If you can't make a global change to force responses as JSON, then try:

[Route("api/Player/videos")] public HttpResponseMessage GetVideoMappings() {     var model = new MyCarModel();     return Request.CreateResponse(HttpStatusCode.OK,model,Configuration.Formatters.JsonFormatter); } 

OR

[Route("api/Player/videos")] public IHttpActionResult GetVideoMappings() {     var model = new MyCarModel();     return Json(model);     } 

If you want to change globally, then first go to YourProject/App_Start/WebApiConfig.cs and add:

config.Formatters.XmlFormatter.SupportedMediaTypes.Remove( config.Formatters.XmlFormatter.SupportedMediaTypes.FirstOrDefault(t => t.MediaType == "application/xml")); 

at the bottom of the Register method.

Then try:

[Route("api/Player/videos")] public IHttpActionResult GetVideoMappings() {     var model = new MyCarModel();     return Ok(model);     } 

Answer 2

The XML is returned instead JSON because the caller is requesting XML. The returned format can be forced to JSON using a filter that adds the header you need and lets MVC resolve the JSON.

public class AcceptHeaderJsonAttribute : ActionFilterAttribute {     public override void OnActionExecuting(System.Web.Http.Controllers.HttpActionContext actionContext)     {         actionContext.Request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));         } } 

So you can decorate the method you want to force a JSON response with this attribute and keep the same global JSON configuration and serialization as any other method.