Django: Make certain fields in a ModelForm required=False

How do I make certain fields in a ModelForm required=False?

If I have:

class ThatForm(ModelForm):
  class Meta:
    widgets = {"text": Textarea(required=False)}

Or if I have:

class ThatForm(ModelForm):
  text = Textarea(required=False)

Django returns:

__init__() got an unexpected keyword argument 'required'

following from comments. Probably yes:

class ThatForm(ModelForm):
    def __init__(self, *args, **kwargs):
        # first call parent's constructor
        super(ThatForm, self).__init__(*args, **kwargs)
        # there's a `fields` property now
        self.fields['desired_field_name'].required = False

you ought to add blank=True to the corresponding model

The documentation says

If the model field has blank=True, then required is set to False on the form field. Otherwise, required=True.

Also see the documentation for blank itself.