#24912: prefetch_related fails with sqlite3 database and UUIDField primary keys
-------------------------------------+-------------------------------------
     Reporter:  brki                 |                    Owner:  zedr
         Type:  Bug                  |                   Status:  assigned
    Component:  Database layer       |                  Version:  master
  (models, ORM)                      |
     Severity:  Normal               |               Resolution:
     Keywords:  UUIDField            |             Triage Stage:  Accepted
    Has patch:  0                    |      Needs documentation:  0
  Needs tests:  0                    |  Patch needs improvement:  0
Easy pickings:  0                    |                    UI/UX:  0
-------------------------------------+-------------------------------------

Comment (by zedr):

 I'm seeing this in the db logs:



 {{{
 >>> players = Player.objects.filter(id=self.player_id)
 >>> player_ = players.get()
 >>> self.assertEqual(2, player_.awards.count())

 (0.000) QUERY = 'SELECT "model_fields_player"."id",
 "model_fields_player"."name" FROM "model_fields_player" WHERE
 "model_fields_player"."id" = %s' - PARAMS =
 ('01e6706e12f6465387abaeb1cf0c6389',);
 args=('01e6706e12f6465387abaeb1cf0c6389',)

 (0.000) QUERY = 'SELECT COUNT(%s) AS "__count" FROM "model_fields_award"
 INNER JOIN "model_fields_player_awards" ON ( "model_fields_award"."id" =
 "model_fields_player_awards"."award_id" ) WHERE
 "model_fields_player_awards"."player_id" = %s' - PARAMS = ('*',
 '01e6706e12f6465387abaeb1cf0c6389'); args=('*',
 '01e6706e12f6465387abaeb1cf0c6389')
 }}}

 {{{
 >>> players = players.prefetch_related('awards')
 >>> player = players.get()
 >>> # For sqlite3, this fails with "2 != 0":
 >>> self.assertEqual(2, player.awards.count())

 (0.000) QUERY = 'SELECT "model_fields_player"."id",
 "model_fields_player"."name" FROM "model_fields_player" WHERE
 "model_fields_player"."id" = %s' - PARAMS =
 ('01e6706e12f6465387abaeb1cf0c6389',);
 args=('01e6706e12f6465387abaeb1cf0c6389',)

 (0.000) QUERY = 'SELECT ("model_fields_player_awards"."player_id") AS
 "_prefetch_related_val_player_id", "model_fields_award"."id",
 "model_fields_award"."name" FROM "model_fields_award" INNER JOIN
 "model_fields_player_awards" ON ( "model_fields_award"."id" =
 "model_fields_player_awards"."award_id" ) WHERE
 "model_fields_player_awards"."player_id" IN (%s)' - PARAMS =
 ('01e6706e12f6465387abaeb1cf0c6389',);
 args=('01e6706e12f6465387abaeb1cf0c6389',)
 }}}

--
Ticket URL: <https://code.djangoproject.com/ticket/24912#comment:4>
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