title: Django forms.ChoiceField without validation of selected value
body: <p>Django ChoiceField "Validates that the given value exists in the list of choices."</p>
  
  <p>I want a ChoiceField (so I can input choices in the view) but I don't want Django to check if the choice is in the list of choices. It's complicated to explain why but this is what I need. How would this be achieved? </p>