Re: Custom form field validation and required=False

Thanks for that, using:

from django.core import validators
.
.
class ExistingUserField(forms.CharField):
def clean(self, value):
if value in validators.EMPTY_VALUES:
return value

did the trick.

Paddy

On Jul 17, 3:31 am, Nuno Maltez <nuno.li...@gmail.com> wrote:
> Hi,
>
> Looking at Django's forms/fiedls.py may give you some ideas.
>
> The test for an empty value is
>
> if value in validators.EMPTY_VALUES
>
> You can also use self.required to see if the required attribute is set
> (e.g., see Field's validate() method).
>
> Of course, a username with a single space will still raise your "User
> not found" exception using this method  - but I think it's standard
> behaviour for all Fields (try inserting a space in an integer field).
>
> You're also ignoring validators on your custom clean method, but I
> guess that's because you know you won't need them :)
>
> """
> The clean() method on a Field subclass. This is responsible for
> running to_python, validate and run_validators in the correct order
> and propagating their errors. If, at any time, any of the methods
> raise ValidationError, the validation stops and that error is raised.
> This method returns the clean data, which is then inserted into the
> cleaned_data dictionary of the form.
> """http://docs.djangoproject.com/en/dev/ref/forms/validation/
>
> hth,
> Nuno
>
> On Fri, Jul 16, 2010 at 2:01 PM, Paddy Joy <paddy...@gmail.com> wrote:
> > I'm trying to create a custom form field that will validate against
> > auth.user. The field should throw a validation error if the user does
> > not exist, otherwise the field should validate.
>
> > So far I have:
>
> > class ExistingUserField(forms.CharField):
> >    def clean(self, value):
> >        # Check if the user exists
> >        try:
> >            user = User.objects.get(username=value)
> >        except:
> >            # User does not exist
> >            raise forms.ValidationError('User %s not found' % value)
> >       return value
>
> > I then use this in a form as:
>
> > class MyForm(forms.Form):
> >    user = ExistingUserField(required=False)
>
> > This code works as expected when the user field is populated but does
> > not honour the "required=False" argument, when the user field is left
> > blank the error "User not found" is raised.
>
> > Do i need to check for all forms of None and blank strings? Is there a
> > better way?
>
> > Paddy
>
> > --
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>
>

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