#23423: Integrate unaccent lookups in django.contrib.postgres
-------------------------------------+-------------------------------------
Reporter: Thomas Chaumeny | Owner: Thomas
| Chaumeny
Type: New feature | Status: closed
Component: contrib.postgres | Version: master
Severity: Normal | Resolution: fixed
Keywords: | Triage Stage: Ready for
| checkin
Has patch: 1 | Needs documentation: 1
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by Gabor Körber):
bilaterality of this function maybe should be explained in the
documentation.
also there is a caveat, and i want to comment it here, as this
implementation caused me to debug for a while:
if i do (please note how the sequence of enclosing is for unaccent and
lower, also what follows are just abstract examples, i know there are
possible workarounds!)
{{{#!python
Model.objects.annotate(a_value=Unaccent(Lower('fieldname'))).filter(
a_value=Lower( 'another_field_or_Value' ) )
}}}
you would expect (abstractly) something like this SQL:
SELECT * WHERE unaccent(lower(fieldname)) = lower(another_field_or_Value);
however what you get is (because of bilateral "magic"):
SELECT * WHERE unaccent(lower(fieldname)) =
lower(unaccent(another_field_or_Value))
less of a problem, as most likely you would want anyway something like
{{{#!python
Model.objects.annotate(a_value=Unaccent(Lower('fieldname'))).filter(
a_value=Unaccent(Lower( 'another_field_or_Value' )) )
}}}
however this expression results in django as
SELECT * WHERE unaccent(lower(fieldname)) =
unaccent(lower(unaccent(another_field_or_Value)))
this would not make much issues, you can just leave out unaccent on RHS as
you will get it from annotate, especially if lower and unaccent were
interchangable in their position
but they are not, there are exceptions
see in postgres:
select lower(unaccent('ÇÁÈÎËßÖÜ')), unaccent(lower('ÇÁÈÎËßÖÜ'));
results in "caeiesou", "caeieSou"
and these are just the european exceptions i checked, but be warned.
--
Ticket URL: <https://code.djangoproject.com/ticket/23423#comment:10>
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