How to throw exception in Web API?

Question

How can I throw a exception to in ASP.net Web Api?

Below is my code:

public Test GetTestId(string id)
{
    Test test = _test.GetTest(id);

    if (test == null)
    {
        throw new HttpResponseException(HttpStatusCode.NotFound);
    }

    return test;
}

I don't think I am doing the right thing, How do my client know it is a HTTP 404 error?

score 75 · Accepted Answer · edited Nov 10 '16 at 09:33

75

It's absolutely fine.

Alternatively, if you wish to provide more info (to allow, as you say, the client to distinguish from regular 404):

    if (test == null)
    {
         throw new HttpResponseException(Request.CreateErrorResponse(HttpStatusCode.NotFound, 
"this item does not exist"));
    }

edited Nov 10 '16 at 09:33

Divyang Desai

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answered Jan 30 '13 at 15:52

Filip W

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2

But when I host it to the web server, I always get a HTTP 500 error. – Alvin Jan 30 '13 at 23:13
@Alvin Are you inheriting your controller from ApiController? Also check if this GetTestId method is NOT called from a constructor, just to be sure. If everything fails, try the following to throw the error: throw new HttpException((int)HttpStatusCode.NotFound,"this item does not exist"); – Ε Г И І И О Jan 06 '20 at 04:21

score 6 · Answer 2 · edited Feb 12 '21 at 23:42

6

This blogpost should help you understand WebAPI error handling a bit better.

What you have in your code snippet should work. The server will send back a 404 Not Found to the client if test is null with no response body. If you want a response body, you should consider using Request.CreateErrorResponse as explained in the blog post above and passing that response to the HttpResponseException.

edited Feb 12 '21 at 23:42

Osama Rizwan

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answered Jan 30 '13 at 15:51

Youssef Moussaoui

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How to throw exception in Web API?

2 Answers2

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