title: How to redirect and then display errors with Google App Engine
body: <p>I'm working on a Google App Engine project that collects stories submitted by users.</p>
  
  <p>This is how I handle submission errors in the post method of my Request Handler:</p>
  
  <pre><code># get the title and content using self.request.get()
  errors = []
  if not title:
      errors.append("Please enter a title.")
  if not content:
      errors.append("Please enter a story.")
  if not errors:
      # create the story, save it to the database
      # redirect to the story's page
  else:
      # pass the title and/or content to a template
      # pass the error message(s) to a template
      # the same template that displays the submission form is used here
  </code></pre>
  
  <p><b>The problem:</b> since my form sends posts to <b>example.com/createstory.do</b> -- if there are errors I end up redisplaying the form page  at that address. </p>
  
  <p><b>What I want to happen:</b> redirect the user back the page where they submitted the form: <b>example.com/Share</b>, while at the same time displaying the error messages and redisplaying the submitted form data.</p>
  
  <p>What's the easiest way to do this?</p>
  
  <p>I know I could just have <b>/Share</b> handle both get and post requests, but I'm looking for a solution that I can use even when doing that wouldn't be an option. </p>