fields.py 文件源码

def clean(self, data, initial=None):
        # If the widget got contradictory inputs, we raise a validation error
        if data is FILE_INPUT_CONTRADICTION:
            raise ValidationError(self.error_messages['contradiction'], code='contradiction')
        # False means the field value should be cleared; further validation is
        # not needed.
        if data is False:
            if not self.required:
                return False
            # If the field is required, clearing is not possible (the widget
            # shouldn't return False data in that case anyway). False is not
            # in self.empty_value; if a False value makes it this far
            # it should be validated from here on out as None (so it will be
            # caught by the required check).
            data = None
        if not data and initial:
            return initial
        return super(FileField, self).clean(data)