#26379: Document that first filter() chained to a RelatedManager is sticky
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Reporter: Balázs Oroszi | Owner: Annabelle
| Wiegart
Type: Bug | Status: assigned
Component: Documentation | Version: 1.9
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by Annabelle Wiegart):
While trying to replicate the sticky vs. permissive filter behaviour with
the docs example, I discovered another quite surprising twist. In this
example without an explicit through model, I was not able to reproduce the
permissive filter behaviour:
{{{
>>> from django.db.models import Q
>>> arg1 = Q(headline__contains="Lennon")
>>> arg2 = Q(headline__contains="Best")
>>> q12 = taylor.texts.filter(arg1&arg2)
>>> q12
<QuerySet []>
>>> q13 = taylor.texts.filter(arg1).filter(arg2)
>>> q13
<QuerySet []>
>>> print(q13.query)
SELECT "filterexample_entry"."id", "filterexample_entry"."blog_id",
"filterexample_entry"."headline", "filterexample_entry"."body_text",
"filterexample_entry"."pub_date", "filterexample_entry"."mod_date",
"filterexample_entry"."number_of_comments",
"filterexample_entry"."number_of_pingbacks",
"filterexample_entry"."rating" FROM "filterexample_entry" INNER JOIN
"filterexample_entry_authors" ON ("filterexample_entry"."id" =
"filterexample_entry_authors"."entry_id") WHERE
("filterexample_entry_authors"."author_id" = 2 AND
"filterexample_entry"."headline"::text LIKE %Lennon% AND
"filterexample_entry"."headline"::text LIKE %Best%)
}}}
I would have expected q13 to produce a double JOIN and result in a
permissive filter, but it didn't.
Does an explicit through model make a difference in the end?
--
Ticket URL: <https://code.djangoproject.com/ticket/26379#comment:17>
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