Fixed #29986 -- Added .format() support to ngettext_lazy strings.

django/utils/translation/__init__.py

@@ -110,20 +110,30 @@ def lazy_number(func, resultclass, number=None, **kwargs):
             def __bool__(self):
                 return bool(kwargs['singular'])
 
+            def _get_number_value(self, values):
+                try:
+                    return values[number]
+                except KeyError:
+                    raise KeyError(
+                        "Your dictionary lacks key '%s\'. Please provide "
+                        "it, because it is required to determine whether "
+                        "string is singular or plural." % number
+                    )
+
+            def _translate(self, number_value):
+                kwargs['number'] = number_value
+                return func(**kwargs)
+
+            def format(self, *args, **kwargs):
+                number_value = self._get_number_value(kwargs) if kwargs and number else args[0]
+                return self._translate(number_value).format(*args, **kwargs)
+
             def __mod__(self, rhs):
                 if isinstance(rhs, dict) and number:
-                    try:
-                        number_value = rhs[number]
-                    except KeyError:
-                        raise KeyError(
-                            "Your dictionary lacks key '%s\'. Please provide "
-                            "it, because it is required to determine whether "
-                            "string is singular or plural." % number
-                        )
+                    number_value = self._get_number_value(rhs)
                 else:
                     number_value = rhs
-                kwargs['number'] = number_value
-                translated = func(**kwargs)
+                translated = self._translate(number_value)
                 try:
                     translated = translated % rhs
                 except TypeError:

tests/i18n/other/locale/de/LC_MESSAGES/django.po

@@ -107,4 +107,30 @@ msgstr "Es gibt %(num_comments)s Kommentare"
 #: models.py:23
 msgctxt "other comment count"
 msgid "There are %(num_comments)s comments"
-msgstr "Andere: Es gibt %(num_comments)s Kommentare"
+msgstr "Andere: Es gibt %(num_comments)s Kommentare"
+
+#: tests.py:213
+msgid "{} good result"
+msgid_plural "{} good results"
+msgstr[0] "{} gutes Resultat"
+msgstr[1] "{} guten Resultate"
+
+#: tests.py:214
+msgctxt "Exclamation"
+msgid "{} good result"
+msgid_plural "{} good results"
+msgstr[0] "{} gutes Resultat!"
+msgstr[1] "{} guten Resultate!"
+
+#: tests.py:226
+msgid "Hi {name}, {num} good result"
+msgid_plural "Hi {name}, {num} good results"
+msgstr[0] "Hallo {name}, {num} gutes Resultat"
+msgstr[1] "Hallo {name}, {num} guten Resultate"
+
+#: tests.py:230
+msgctxt "Greeting"
+msgid "Hi {name}, {num} good result"
+msgid_plural "Hi {name}, {num} good results"
+msgstr[0] "Willkommen {name}, {num} gutes Resultat"
+msgstr[1] "Willkommen {name}, {num} guten Resultate"

tests/i18n/tests.py

@@ -208,6 +208,39 @@ class TranslationTests(SimpleTestCase):
             with self.assertRaisesMessage(KeyError, 'Your dictionary lacks key'):
                 complex_context_deferred % {'name': 'Jim'}
 
+    @override_settings(LOCALE_PATHS=extended_locale_paths)
+    def test_ngettext_lazy_format_style(self):
+        simple_with_format = ngettext_lazy('{} good result', '{} good results')
+        simple_context_with_format = npgettext_lazy('Exclamation', '{} good result', '{} good results')
+
+        with translation.override('de'):
+            self.assertEqual(simple_with_format.format(1), '1 gutes Resultat')
+            self.assertEqual(simple_with_format.format(4), '4 guten Resultate')
+            self.assertEqual(simple_context_with_format.format(1), '1 gutes Resultat!')
+            self.assertEqual(simple_context_with_format.format(4), '4 guten Resultate!')
+
+        complex_nonlazy = ngettext_lazy('Hi {name}, {num} good result', 'Hi {name}, {num} good results', 4)
+        complex_deferred = ngettext_lazy(
+            'Hi {name}, {num} good result', 'Hi {name}, {num} good results', 'num'
+        )
+        complex_context_nonlazy = npgettext_lazy(
+            'Greeting', 'Hi {name}, {num} good result', 'Hi {name}, {num} good results', 4
+        )
+        complex_context_deferred = npgettext_lazy(
+            'Greeting', 'Hi {name}, {num} good result', 'Hi {name}, {num} good results', 'num'
+        )
+        with translation.override('de'):
+            self.assertEqual(complex_nonlazy.format(num=4, name='Jim'), 'Hallo Jim, 4 guten Resultate')
+            self.assertEqual(complex_deferred.format(name='Jim', num=1), 'Hallo Jim, 1 gutes Resultat')
+            self.assertEqual(complex_deferred.format(name='Jim', num=5), 'Hallo Jim, 5 guten Resultate')
+            with self.assertRaisesMessage(KeyError, 'Your dictionary lacks key'):
+                complex_deferred.format(name='Jim')
+            self.assertEqual(complex_context_nonlazy.format(num=4, name='Jim'), 'Willkommen Jim, 4 guten Resultate')
+            self.assertEqual(complex_context_deferred.format(name='Jim', num=1), 'Willkommen Jim, 1 gutes Resultat')
+            self.assertEqual(complex_context_deferred.format(name='Jim', num=5), 'Willkommen Jim, 5 guten Resultate')
+            with self.assertRaisesMessage(KeyError, 'Your dictionary lacks key'):
+                complex_context_deferred.format(name='Jim')
+
     def test_ngettext_lazy_bool(self):
         self.assertTrue(ngettext_lazy('%d good result', '%d good results'))
         self.assertFalse(ngettext_lazy('', ''))