Commit 7a3b486c authored by Josh Smeaton's avatar Josh Smeaton Committed by Tim Graham
Browse files

[1.9.x] Fixed #25517 -- Made Concat function idempotent on SQLite. 

Backport of 6c95b134 from master
parent 9039ff60

django/db/models/functions.py

+9 −6
Original line number Diff line number Diff line
@@ -42,10 +42,10 @@ class ConcatPair(Func): 
        super(ConcatPair, self).__init__(left, right, **extra)



    def as_sqlite(self, compiler, connection):

        self.arg_joiner = ' || '

        self.template = '%(expressions)s'

        self.coalesce()

        return super(ConcatPair, self).as_sql(compiler, connection)

        coalesced = self.coalesce()

        coalesced.arg_joiner = ' || '

        coalesced.template = '%(expressions)s'

        return super(ConcatPair, coalesced).as_sql(compiler, connection)



    def as_mysql(self, compiler, connection):

        # Use CONCAT_WS with an empty separator so that NULLs are ignored.
@@ -55,9 +55,12 @@ class ConcatPair(Func): 


    def coalesce(self):

        # null on either side results in null for expression, wrap with coalesce

        c = self.copy()

        expressions = [

            Coalesce(expression, Value('')) for expression in self.get_source_expressions()]

        self.set_source_expressions(expressions)

            Coalesce(expression, Value('')) for expression in c.get_source_expressions()

        ]

        c.set_source_expressions(expressions)

        return c





class Concat(Func):

docs/releases/1.8.6.txt

+2 −0
Original line number Diff line number Diff line
@@ -23,3 +23,5 @@ Bugfixes 
  have their reverse relations disabled (:ticket:`25545`).



* Allowed filtering over a ``RawSQL`` annotation (:ticket:`25506`).



* Made the ``Concat`` database function idempotent on SQLite (:ticket:`25517`).

tests/db_functions/tests.py

+15 −1
Original line number Diff line number Diff line
@@ -7,7 +7,8 @@ from django.db import connection 
from django.db.models import CharField, TextField, Value as V

from django.db.models.expressions import RawSQL

from django.db.models.functions import (

    Coalesce, Concat, Greatest, Least, Length, Lower, Now, Substr, Upper,

    Coalesce, Concat, ConcatPair, Greatest, Least, Length, Lower, Now, Substr,

    Upper,

)

from django.test import TestCase, skipIfDBFeature, skipUnlessDBFeature

from django.utils import six, timezone
@@ -353,6 +354,19 @@ class FunctionTests(TestCase): 
        expected = article.title + ' - ' + article.text

        self.assertEqual(expected.upper(), article.title_text)



    @skipUnless(connection.vendor == 'sqlite', "sqlite specific implementation detail.")

    def test_concat_coalesce_idempotent(self):

        pair = ConcatPair(V('a'), V('b'))

        # Check nodes counts

        self.assertEqual(len(list(pair.flatten())), 3)

        self.assertEqual(len(list(pair.coalesce().flatten())), 7)  # + 2 Coalesce + 2 Value()

        self.assertEqual(len(list(pair.flatten())), 3)



    def test_concat_sql_generation_idempotency(self):

        qs = Article.objects.annotate(description=Concat('title', V(': '), 'summary'))

        # Multiple compilations should not alter the generated query.

        self.assertEqual(str(qs.query), str(qs.all().query))



    def test_lower(self):

        Author.objects.create(name='John Smith', alias='smithj')

        Author.objects.create(name='Rhonda')