.Net Core Web API: How to return a validation message from API method?

Question

I am using React Js in my client-side and.Net Core 3.0 Web API on the server-side. I have one API method called CreateAccount and the return type is IActionResult. Now if I do validate with any one of the model property then I have to send or return the validation message along with empty model data. I am new to API and tried like below but could not send the string as a result type.

API method,

[AllowAnonymous]
[HttpPost("createaccount")]
public async Task<IActionResult> CreateAccount([FromBody]Users user)
{
        try
        {
            if (ModelState.IsValid)
            {
                if (user == null)
                    return BadRequest(new { message = "Data is empty" });

                if(user.UserType!="Admin")
                {
                    return new ValidationResult("Only Admin can create new account");
                }
                return Ok(await _userService.CreateAnUserAccount(user));
            }
        }
        catch(Exception e)
        {
            throw new ArgumentException(e.Message);
        }

        return ValidationProblem();
}

I do not know the proper.Net Core API coding part, could anyone please help me to resolve this issue?

Answer 1

You could return an ObjectResult with a StatusCode other than StatusCodes.Status200OK and a serialized object that contains whatever information you want to return to the client, eg:

return new ObjectResult(new YourApiError() { Message = "message.." })
{ 
     StatusCode = StatusCodes.Status405MethodNotAllowed 
};