python - How do I raise a ValidationError (or do something similar) in views.py of my Django?

Question

I'm using Django forms. I'm validating in the model layer:

def clean_title(self):
    title = self.cleaned_data['title']
    if len(title)  < 5:
        raise forms.ValidationError("Headline must be more than 5 characters.")
    return title

However, there are some things that I need to validate in the views.py . For example...was the last time the user posted something more than a minute ago?

That kind of stuff requires request.user, which the models layer cannot get. So, I must validate in the views.py. How do I do something in the views.py to do the exact thing as this?

raise forms.ValidationError("Headline must be more than 5 characters.")

Answer 1

I think gruszczy's answer is a good one, but if you're after generic validation involving variables that you think are only available in the view, here's an alternative: pass in the vars as arguments to the form and deal with them in the form's main clean() method.

The difference/advantage here is that your view stays simpler and all things related to the form content being acceptable happen in the form.

eg:

# IN YOUR VIEW 
#?pass request.user as a keyword argument to the form
myform = MyForm(user=request.user)


# IN YOUR forms.py
# at the top:

from myapp.foo.bar import ok_to_post # some abstracted utility you write to rate-limit posting 

# and in your particular Form definition

class MyForm(forms.Form)

   ... your fields here ...

   def __init__(self, *args, **kwargs):
      self.user = kwargs.pop('user')  # cache the user object you pass in
      super(MyForm, self).__init__(*args, **kwargs)  # and carry on to init the form


   def clean(self):
      # test the rate limit by passing in the cached user object

      if not ok_to_post(self.user):  # use your throttling utility here
          raise forms.ValidationError("You cannot post more than once every x minutes")

      return self.cleaned_data  # never forget this! ;o)

Note that raising a generic ValidationError in the clean() method will put the error into myform.non_field_errors so you'll have to make sure that your template contains {{form.non_field_errors}} if you're manually displaying your form