Post handler to insert an Assignment for our GradeRecorder web app

InsertAssignmentAction.py

class InsertAssignmentAction(webapp2.RequestHandler):
  def post(self):
    user = users.get_current_user()
    urlsafe_entity_key = self.request.get('assignment_entity_key')
    if len(urlsafe_entity_key) > 0:
      # Edit
      assignment_key = ndb.Key(urlsafe=urlsafe_entity_key)
      assignment = assignment_key.get()
    else:
      # Add
      assignment = Assignment(parent=utils.get_parent_key(user))
    assignment.name = self.request.get('assignment_name')
    assignment.put()
    self.redirect("/?active_assignment=" + assignment.key.urlsafe())