title: REST api for field validation
body: <p>I have to create a couple of web services for validating possible values of given fields. I'm contemplating having something like:</p>
  
  <pre><code>POST /entity/fieldName body { fieldValues }
  </code></pre>
  
  <p>where the POST will return 400 (Bad request) if the arguments are invalid and 422 (Unprocessable entity) otherwise. However I do not really like the 422 response part very much since it makes the request always return an error. On the other hand since I'm only doing validation and this is a POST I don't want to actually create a new resource on the server (i.e. return 200). Is there another HTTP method / API endpoint that is better suit for this? For what it's worth I will be checking that the entity field with <code>&lt;fieldName&gt;</code> has its value in a given range.</p>