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.
3 Answers
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);
}
}
3 Comments
JobaDiniz
do we need to instantiate a new formmater? can't we tweak the current instance or the change will be applied everywhere?
Federico Dipuma
@JobaDiniz as you stated, if you change properties of the original formatter, those changes will affect every other controller
gius
Nice initialization of SerializerSettings! I didn't know about that C# feature.
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);
}
}
1 Comment
R. Salisbury
I used this code but I gave it a
Type ContractResolverType property and then did ContractResolver = (IContractResolver)Activator.CreateInstance(ContractResolverType) so I don't have to create one of these for each contract resolver type. In use it looks like this: [ActionContractResolver(ContractResolverType = typeof(DefaultContractResolver))]I needed to return a 404 status error code alongside a json object with error details. I solved it using WebApi.Content with a new new JsonMediaTypeFormatter.
public class MyController : ApiController
{
public IHttpActionResult Get()
{
// Configure new Json formatter
var formatter = new JsonMediaTypeFormatter
{
SerializerSettings =
{
TypeNameHandling = TypeNameHandling.None,
PreserveReferencesHandling = PreserveReferencesHandling.None,
Culture = CultureInfo.InvariantCulture,
Formatting = Formatting.Indented,
NullValueHandling = NullValueHandling.Ignore
}
};
try
{
var model = new MyModel();
return Content(HttpStatusCode.OK, model, formatter);
}
catch (Exception err)
{
var errorDto = GetErrorDto(HttpStatusCode.NotFound, $"{err.Message}");
return Content(HttpStatusCode.NotFound, errorDto, formatter);
}
}
}
HttpResponseMessagemanually setting the content to your desired json output? It's not as tidy as dealing with a global formatter but you can still create DRY helpers for dealing with these one off situations.