WebApi2 OData return custom error object

Hello,

I've searched this intensive but can't get it to work.

I've haven an Web AP2 OData API and need to return a custom error class.

Here is what I have:

public class Error
{
public string Code { get; set; }
public string Message { get; set; }
}

In Global.asax.cs

protected void Application_Start()
{
GlobalConfiguration.Configure(WebApiConfig.Register);

GlobalConfiguration.Configuration.MessageHandlers.Add(new MessageInterceptor());
}

public class MessageInterceptor : DelegatingHandler
{
protected override Task SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{

return base.SendAsync(request, cancellationToken).ContinueWith(
task =>
{
var body = task.Result.Content.ReadAsStringAsync().Result;
var resultObj = JsonConvert.DeserializeObject(body.Replace("value", "Results"));
task.Result.Content = new ObjectContent(typeof(object), resultObj, new JsonMediaTypeFormatter());
return task.Result;
}, cancellationToken);
}
}

In WebApiConfig,cs

public static class WebApiConfig
{
public static void Register(HttpConfiguration config)
{

config.Filters.Add(new HandleApiExceptionAttribute());

}

public class HandleApiExceptionAttribute : ExceptionFilterAttribute, IExceptionFilter
{
public override void OnException(HttpActionExecutedContext context)
{
if (context.Exception is Error)
{
var res = context.Exception.Message;

//Define the Response Message
HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.InternalServerError)
{
Content = new StringContent(res),
ReasonPhrase = res
};

//Create the Error Response
context.Response = response;
}
}

public class OrdersController : ODataControllerA controller
{
private Context db = new Context();

// GET: odata/Orders
[Queryable]
public IQueryable GetOrders(ODataQueryOptions opts)

{

Error theError = new Error()
{
Code = "1000",
Message = "Geen filter gespecificeerd"
};

HttpResponseMessage response = Request.CreateResponse(HttpStatusCode.BadRequest, theError);
//return Request.CreateResponse(HttpStatusCode.BadRequest, theError);
throw new HttpResponseException(response);

}

When I try this this crashes in teh MessageInterceptor.

This is there because a third party consuming the API want's it in the specific format.

When the code runs correct is return results{}

On error it should return Error{code:, message: }

Anyone ideas?

Jeroen

This is what I cam up with:

I changed the controller to:

public IHttpActionResult GetOrders(ODataQueryOptions opts)
{
else
{
Error theError = new Error()
{
Code = "1000",
Message = "Geen filter gespecificeerd"
};
return new ErrorResult(theError, Request)
}
return Ok(resultList);
}

Using this class

public class ErrorResult : IHttpActionResult
{
Error _error;
HttpRequestMessage _request;
public ErrorResult(Error error, HttpRequestMessage request)
{
_error = error;
_request = request;
}
public Task ExecuteAsync(CancellationToken cancellationToken)
{
List _errorList = new List();
_errorList.Add(_error);
error err = new error()
{
errors = _errorList
};
var response = new HttpResponseMessage(HttpStatusCode.BadRequest)
{
Content = new ObjectContent(err, new JsonMediaTypeFormatter()),
RequestMessage = _request
};
return Task.FromResult(response);
}
}
public class Error
{
public string Code { get; set; }
public string Message { get; set; }
}
public class error
{
public List errors { get; set; }
}

1 Reply

Know the answer? Post it — somebody with the same question will find it here.

Jeroen Everhard9y ago
This is what I cam up with:

I changed the controller to:
public IHttpActionResult GetOrders(ODataQueryOptions opts)
        {
else
            {

                Error theError = new Error()
                {
                    Code = "1000",
                    Message = "Geen filter gespecificeerd"
                };

                return new ErrorResult(theError, Request)
            }

            return Ok(resultList);
        }
Using this class
public class ErrorResult : IHttpActionResult
    {
        Error _error;
        HttpRequestMessage _request;

        public ErrorResult(Error error, HttpRequestMessage request)
        {
            _error = error;
            _request = request;
        }

        public Task ExecuteAsync(CancellationToken cancellationToken)
        {

            List _errorList = new List();
            _errorList.Add(_error);

            error err = new error()
            {
                errors = _errorList
            };

            var response = new HttpResponseMessage(HttpStatusCode.BadRequest)
            {
                Content = new ObjectContent(err, new JsonMediaTypeFormatter()),
                RequestMessage = _request
            };
            return Task.FromResult(response);
        }
    }

    public class Error
    {
        public string Code { get; set; }
        public string Message { get; set; }
    }

    public class error
    {
        public List errors { get; set; }
    }