HTTP Response for Unsuccessful Handling of Request

Question

Let's say I have a REST POST end-point: www.foo.com/id/X where X represents a number.

My server-side pseudocode looks like this:

performIdLookup(int id) { 

  if ( idExists(id) ) {
     return toJson(lookup(id)) // returns 200/OK Status Code with object as JSON
  }
  else {
     return HTTP_???_error 
  }
}

Per this question , sending a 400 error doesn't seem right here since the user submitted a valid request, but the server couldn't locate it.

What's the right HTTP response here and why?

Answer 1

That is very easy.

404 Not Found

If there is no resourece at /id/42 , a resource can not be found for this URL.

See the list of HTTP status codes .

Answer 2

Not 400 (bad request). But 404 (not found). Yes, 404 is not what we are used to watching in these cases, but you can add some custom information with response.