django - how can I access the form field from inside a custom widget

Question

The below class inherits from the Textarea widget and features javascript code that displays how many characters more a user can enter in a textarea.

Answer 1

Although not required for solving your problem, access to the form or form field may be indeed useful sometimes. See the full answer at another question, but in short, you can bind the form or field to the widget manually in form __init__:

class MyForm(forms.ModelForm):
    foo = forms.ModelChoiceField(Foo.objects, widget=CustomWidget())

    class Meta:
        model = Bar

    def __init__(self, *args, **kwargs):
        super(MyForm, self).__init__(*args, **kwargs)
        self.fields['foo'].widget.form_instance = self

Answer 2

Technically, a Widget doesn't have to have a direct relationship back to a Field, so you don't do this.

Looking at the source of CharField, you can see that it has a widget_attrs method which automatically adds the maxlength attribute to TextInput / PasswordInput fields.

I suggest you use a custom Field which overrides this method and adds an attribute for your custom Widget.

Also, I'm not sure that leaving it in attrs is a good idea anyway - the <TextArea> will be rendered with an invalid max_length argument. Perhaps you should be pop()ing it off instead?