From 7acbe89cc2a72f1b85d415c1cdb622c0dbbbe37c Mon Sep 17 00:00:00 2001 From: Tim Graham Date: Tue, 13 Jun 2017 14:16:52 -0400 Subject: [PATCH] Refs #23853 -- Updated sql.query.Query.join() docstring. Follow up to ab89414f40db1598364a7fe4cfac1766cacd2668. --- django/db/models/sql/query.py | 25 +++++++------------------ 1 file changed, 7 insertions(+), 18 deletions(-) diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py index 656482e102..d3ab487ba7 100644 --- a/django/db/models/sql/query.py +++ b/django/db/models/sql/query.py @@ -894,27 +894,16 @@ class Query: def join(self, join, reuse=None): """ - Return an alias for the join in 'connection', either reusing an - existing alias for that join or creating a new one. 'connection' is a - tuple (lhs, table, join_cols) where 'lhs' is either an existing - table alias or a table name. 'join_cols' is a tuple of tuples containing - columns to join on ((l_id1, r_id1), (l_id2, r_id2)). The join corresponds - to the SQL equivalent of:: + Return an alias for the 'join', either reusing an existing alias for + that join or creating a new one. 'join' is either a + sql.datastructures.BaseTable or Join. - lhs.l_id1 = table.r_id1 AND lhs.l_id2 = table.r_id2 - - The 'reuse' parameter can be either None which means all joins - (matching the connection) are reusable, or it can be a set containing - the aliases that can be reused. + The 'reuse' parameter can be either None which means all joins are + reusable, or it can be a set containing the aliases that can be reused. A join is always created as LOUTER if the lhs alias is LOUTER to make - sure we do not generate chains like t1 LOUTER t2 INNER t3. All new - joins are created as LOUTER if nullable is True. - - If 'nullable' is True, the join can potentially involve NULL values and - is a candidate for promotion (to "left outer") when combining querysets. - - The 'join_field' is the field we are joining along (if any). + sure chains like t1 LOUTER t2 INNER t3 aren't generated. All new + joins are created as LOUTER if the join is nullable. """ reuse = [a for a, j in self.alias_map.items() if (reuse is None or a in reuse) and j == join]