From 9fefa0874502b820752d4b323a80e5015e211803 Mon Sep 17 00:00:00 2001 From: Adrian Torres Date: Thu, 16 Jul 2020 08:59:43 +0000 Subject: [FIX] core: mapped() does not prefetch as expected Before this commit, calling `mapped()` on a relational field of a single record inside a for loop does not correctly propagate the prefetch ids from the bigger recordset down to the record inside the loop: [rec.line_ids.mapped('name') for rec in recs] To be more precise, `recs` correctly propagates prefetching information down to `rec.line_ids`, but method `mapped()` does not pass it along to the record that triggers the prefetching. This resulted in one query per record in `recs`, so if `recs` were a 1000 records recordset, at least 1000 queries would be necessary. With this commit, the `mapped()` function correctly propagates the `_prefetch_ids` of the larger recordset (`rec.line_ids`) so that the prefetching works properly and the 1000 queries are brought down to 1. This commit is a followup on #42611. closes odoo/odoo#54565 X-original-commit: 0e97053fee36c0c76b70cb94be5340c3144b178b Signed-off-by: Raphael Collet (rco) Signed-off-by: Adrian Torres (adt) --- odoo/fields.py | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'odoo/fields.py') diff --git a/odoo/fields.py b/odoo/fields.py index 6ad32a505b6..31d67bc6556 100644 --- a/odoo/fields.py +++ b/odoo/fields.py @@ -1018,8 +1018,12 @@ class Field(MetaField('DummyField', (object,), {})): # retrieve values in cache, and fetch missing ones vals = records.env.cache.get_until_miss(records, self) while len(vals) < len(records): - # trigger prefetching on remaining records, and continue retrieval - remaining = records[len(vals):] + # It is important to construct a 'remaining' recordset with the + # _prefetch_ids of the original recordset, in order to prefetch as + # many records as possible. If not done this way, scenarios such as + # [rec.line_ids.mapped('name') for rec in recs] would generate one + # query per record in `recs`! + remaining = records._browse(records.env, records[len(vals):]._ids, records._prefetch_ids) self.__get__(first(remaining), type(remaining)) vals += records.env.cache.get_until_miss(remaining, self) -- cgit v1.2.3