orm.py 文件源码

def conv_NullBooleanField(self, model, field, kwargs):
        from django.db.models.fields import NOT_PROVIDED

        def coerce_nullbool(value):
            d = {'None': None, None: None, 'True': True, 'False': False}
            if isinstance(value, NOT_PROVIDED):
                return None
            elif value in d:
                return d[value]
            else:
                return bool(int(value))

        choices = ((None, 'Unknown'), (True, 'Yes'), (False, 'No'))
        return f.SelectField(choices=choices, coerce=coerce_nullbool, **kwargs)