id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
20122	Pluralize filter sometimes returns singular form instead of an empty string for invalid inputs	Aymeric Augustin	Tobias Kunze	"Filters are documented to return either their input unchanged, or the empty string, whatever makes most sense, when they're used incorrectly. The `pluralize` filter returns the empty string in such cases, for instance when it receives more than two forms (singular, plural).

However, it returns the singular form instead of the empty string when it's passed an object that isn't a number, a string or a list.

Failing test case:

{{{
--- a/tests/defaultfilters/tests.py
+++ b/tests/defaultfilters/tests.py
@@ -622,6 +622,9 @@ class DefaultFiltersTests(TestCase):
         self.assertEqual(pluralize(2,'y,ies'), 'ies')
         self.assertEqual(pluralize(0,'y,ies,error'), '')
 
+    def test_pluralize_error(self):
+        self.assertEqual(pluralize(object, 'y,ies'), '')
+
     def test_phone2numeric(self):
         self.assertEqual(phone2numeric_filter('0800 flowers'), '0800 3569377')
 
}}}

I understand that the implementation is crafted to avoid `isinstance` checks, but in this case we really want different logic depending on the type of the input. I think the filter should be rewritten with the following pseudo-code:

{{{
if the value is a number:
    return singular if value is 1 else plural
if the value is a string:
    return singular if value is '1' else plural
if the value has a length (needs a try/except TypeError):
    return singular if length is 1 else plural
return ''
}}}

I discovered this while working on #16723."	Cleanup/optimization	closed	Template system	dev	Normal	fixed		Jorge C. Leitão	Accepted	1	0	0	0	0	0