__init__.py 文件源码

def _check_max_length_attribute(self, **kwargs):
        if self.max_length is None:
            return [
                checks.Error(
                    "CharFields must define a 'max_length' attribute.",
                    hint=None,
                    obj=self,
                    id='fields.E120',
                )
            ]
        elif not isinstance(self.max_length, six.integer_types) or self.max_length <= 0:
            return [
                checks.Error(
                    "'max_length' must be a positive integer.",
                    hint=None,
                    obj=self,
                    id='fields.E121',
                )
            ]
        else:
            return []