dal.py 文件源码

def expand(self, expression, field_type=None):
        if isinstance(expression, Field):
            if expression.type in ('text', 'blob', 'json'):
                raise SyntaxError('AppEngine does not index by: %s' % expression.type)
            return expression.name
        elif isinstance(expression, (Expression, Query)):
            if not expression.second is None:
                return expression.op(expression.first, expression.second)
            elif not expression.first is None:
                return expression.op(expression.first)
            else:
                return expression.op()
        elif field_type:
                return self.represent(expression, field_type)
        elif isinstance(expression, (list, tuple)):
            return ','.join([self.represent(item, field_type) for item in expression])
        else:
            return str(expression)

    ### TODO from gql.py Expression