database.py 文件源码

def select(self, query, model_class=None, settings=None):
        '''
        Performs a query and returns a generator of model instances.

        - `query`: the SQL query to execute.
        - `model_class`: the model class matching the query's table,
          or `None` for getting back instances of an ad-hoc model.
        - `settings`: query settings to send as HTTP GET parameters
        '''
        query += ' FORMAT TabSeparatedWithNamesAndTypes'
        query = self._substitute(query, model_class)
        r = self._send(query, settings, True)
        lines = r.iter_lines()
        field_names = parse_tsv(next(lines))
        field_types = parse_tsv(next(lines))
        model_class = model_class or ModelBase.create_ad_hoc_model(zip(field_names, field_types))
        for line in lines:
            # skip blank line left by WITH TOTALS modifier
            if line:
                yield model_class.from_tsv(line, field_names, self.server_timezone, self)