mapper.py 文件源码

def _compile(self, whereclause = None, **kwargs):
        order_by = kwargs.pop('order_by', False)
        if order_by is False:
            order_by = self.order_by
        if order_by is False:
            if self.table.default_order_by() is not None:
                order_by = self.table.default_order_by()

        if self._should_nest(**kwargs):
            s2 = sql.select(self.table.primary_key, whereclause, use_labels=True, **kwargs)
            if not kwargs.get('distinct', False) and order_by:
                s2.order_by(*util.to_list(order_by))
            s3 = s2.alias('rowcount')
            crit = []
            for i in range(0, len(self.table.primary_key)):
                crit.append(s3.primary_key[i] == self.table.primary_key[i])
            statement = sql.select([], sql.and_(*crit), from_obj=[self.table], use_labels=True)
            if order_by:
                statement.order_by(*util.to_list(order_by))
        else:
            statement = sql.select([], whereclause, from_obj=[self.table], use_labels=True, **kwargs)
            if order_by:
                statement.order_by(*util.to_list(order_by))
            # for a DISTINCT query, you need the columns explicitly specified in order
            # to use it in "order_by".  insure they are in the column criterion (particularly oid).
            # TODO: this should be done at the SQL level not the mapper level
            if kwargs.get('distinct', False) and order_by:
                statement.append_column(*util.to_list(order_by))
        # plugin point


        # give all the attached properties a chance to modify the query
        for key, value in self.props.iteritems():
            value.setup(key, statement, **kwargs) 
        return statement