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);     } } 

Answer 2

Here's an implementation of the above as Action Attribute:

public class CustomActionJsonFormatAttribute : ActionFilterAttribute {     public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)     {         if (actionExecutedContext?.Response == null) return;          var content = actionExecutedContext.Response.Content as ObjectContent;          if (content?.Formatter is JsonMediaTypeFormatter)         {             var formatter = new JsonMediaTypeFormatter             {                 SerializerSettings =                 {                     ContractResolver = new CamelCasePropertyNamesContractResolver()                 }             };              actionExecutedContext.Response.Content = new ObjectContent(content.ObjectType, content.Value, formatter);         }     } }  public class MyController : ApiController {     [CustomActionJsonFormat]     public IHttpActionResult Get()     {         var model = new MyModel();         return Ok(model);     } }