#23270: select_related on fields pointing to subclasses does not work when using defer ----------------------------------------------+---------------------------- Reporter: islavov | Owner: nobody Type: Uncategorized | Status: new Component: Database layer (models, ORM) | Version: 1.7-rc-2 Severity: Normal | Keywords: select_related Triage Stage: Unreviewed | defer Easy pickings: 0 | Has patch: 0 | UI/UX: 0 ----------------------------------------------+---------------------------- I have the following models {{{ #!python from django.db import models
class Base(models.Model): text = models.TextField() class SubClassA(Base): name = models.CharField(max_length=32) }}} In shell {{{ #!python In [3]: from defertest.models import SubClassA, Base # Select related + defer In [4]: c=Base.objects.select_related("subclassa").defer("text")[0] (0.001) SELECT "defertest_base"."id", "defertest_subclassa"."base_ptr_id", "defertest_subclassa"."name" FROM "defertest_base" LEFT OUTER JOIN "defertest_subclassa" ON ("defertest_base"."id" = "defertest_subclassa"."base_ptr_id") LIMIT 1; args=() # We get an extra query when accessing the subclass In [5]: c.subclassa (0.000) SELECT "defertest_base"."id", "defertest_base"."text", "defertest_subclassa"."base_ptr_id", "defertest_subclassa"."name" FROM "defertest_subclassa" INNER JOIN "defertest_base" ON ("defertest_subclassa"."base_ptr_id" = "defertest_base"."id") WHERE "defertest_subclassa"."base_ptr_id" = 1 ; args=(1,) Out[5]: <SubClassA: SubClassA object> # If no deferred fields In [6]: c=Base.objects.select_related("subclassa")[0] (0.000) SELECT "defertest_base"."id", "defertest_base"."text", "defertest_subclassa"."base_ptr_id", "defertest_subclassa"."name" FROM "defertest_base" LEFT OUTER JOIN "defertest_subclassa" ON ("defertest_base"."id" = "defertest_subclassa"."base_ptr_id") LIMIT 1; args=() # select related works fine ( no extra query ) In [7]: c.subclassa Out[7]: <SubClassA: SubClassA object> }}} -- Ticket URL: <https://code.djangoproject.com/ticket/23270> Django <https://code.djangoproject.com/> The Web framework for perfectionists with deadlines. -- You received this message because you are subscribed to the Google Groups "Django updates" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-updates+unsubscr...@googlegroups.com. To post to this group, send email to django-updates@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/django-updates/050.fc2e87d9020703d142526a0025284c44%40djangoproject.com. For more options, visit https://groups.google.com/d/optout.