title: Regex for disallowing commas
body: <p>I'm trying to disallow commas in a string entered into a textbox. Here is what I have so far:</p>
  
  <pre><code>[RegularExpression (@"?[^,]*$",
          ErrorMessage = "Commas are not allowed in the subtask title. Please remove any and try again")]
  </code></pre>
  
  <p>This is probably my 5th or 6th attempt, nothing so far has worked. Any help would be appreciated.</p>