Can't get error message on BadRequest in Web A

Question

I've googled a lot searching for an answer to my problem with no luck so, let's try if someone else can help me.

I have a Web Api 2 action to register an user after doing some validations. If everything works, it return the serialized user and if don't, an error message sent within a BadRequest response.

At the other hand, I have a WPF client that calls the API for a response.

My problem is that I can't get the reason sent by the error, the client just get the Bad Request error message.

This is a part of the code:

• Web Api Action:

  public async Task<IHttpActionResult> AddUser(NewUserDTO {
      if (!ModelState.IsValid)
      {
          return BadRequest(ModelState);
      }
      if (!model.IdCliente.HasValue)
      {
          ModelState.AddModelError("", "No existe el cliente");
          return BadRequest(ModelState);
      }
      // do save stuff
      return Ok(TheModelFactory.Create(user));
  }
  

• Client function:

  public async Task<ApplicationUserDTO> AddUser(NewUserDTO dto) {
      using (var client = new HttpClient()) {
          client.BaseAddress = new Uri(_urlBase);
          client.DefaultRequestHeaders.Accept.Clear();
          client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
          client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", Token);
          HttpContent content = new StringContent(JsonConvert.SerializeObject(dto));
          content.Headers.ContentType = new MediaTypeHeaderValue("application/json");
          HttpResponseMessage responseMessage = await client.PostAsync("api/accounts/AddUser", content);
          if (responseMessage.IsSuccessStatusCode) {
              var responseJson = await responseMessage.Content.ReadAsStringAsync();
              user = JsonConvert.DeserializeObject<ApplicationUserDTO>(responseJson);
          }
          else
               MessageBox.Show(responseMessage.Content.ReadAsStringAsync().Result);
          return user;
      } 
  }
  

Anyone can help?

Edited:

• DTO:

  [Serializable]
  public class NewUserDTO {
  public int? IdCliente { get; set; }
  [Required]
  public string UserName { get; set; }
  [Required]
  public string Email { get; set; }
  public string Role { get; set; }
  public string Password { get; set; } }
  

Anyway... the dto is sent correctly to api nut, here's the serialized dto as you asked for:

"{\"IdCliente\":null,\"UserName\":\"Toni\",\"Email\":\"[e-mail]\",\"Role\":\"Filtra\",\"Password\":\"TONI\"}"

Answer 1

Have you checked your web.config httpErrors section?

I had the same issue because my web.config looked like this

<httpErrors errorMode="Custom" existingResponse="Replace">
    <clear />
    <error statusCode="404" path="~/Error/NotFound" responseMode="ExecuteURL" />
    <error statusCode="403" path="~/Error/AccessDenied" responseMode="ExecuteURL" />
    <error statusCode="500" path="~/Error/ServerError" responseMode="ExecuteURL" />
</httpErrors>

You must make sure that existingResponse is set to PassThrough

<httpErrors errorMode="Custom" existingResponse="PassThrough">
    <clear />
    <error statusCode="404" path="~/Error/NotFound" responseMode="ExecuteURL" />
    <error statusCode="403" path="~/Error/AccessDenied" responseMode="ExecuteURL" />
    <error statusCode="500" path="~/Error/ServerError" responseMode="ExecuteURL" />
</httpErrors>

Not sure if it will help you, but give it a shot.

Answer 2

API

return new BadRequestErrorMessageResult(yourErrorMessage);

Client

var errorMessage = responseMessage.Content.ReadAsStringAsync().GetAwaiter().GetResult();
MessageBox.Show(errorMessage);

Answer 3

Instead of returning it, throw a request exception:

throw new HttpResponseException(HttpStatusCode.BadRequest);

Unless you require more detail passing o the client in which case you could pass back a Request.CreateErrorResponse but you would need to change the return type to HttpResponseMessage

Answer 4

Finally, I gived up. Maybe some code at web.config, mvc config, api config, filtering or whatever is disturbing and sending a diferent response than the controller does. I added a status code and a message property to my DTO and return always an object. Thanks anyway to all who tried to help me.

Answer 5

Add the line below to WebAPIConfig.cs in the Register method. This will include the error details instead of just the generic 500 internal server error.

        GlobalConfiguration.Configuration.IncludeErrorDetailPolicy = IncludeErrorDetailPolicy.Always;