Fixed #20477: Allowed settings.FORMAT_MODULE_PATH to be a list of modules.

Previously the FORMAT_MODULE_PATH setting only accepted one string (dotted
module path).

This is useful when using several reusable third party apps that define new
formats. We can now use them all and we can even override some of the formats
by providing a project-wide format module.

django/utils/formats.py

@@ -47,10 +47,15 @@ def iter_format_modules(lang, format_module_path=None):
     Does the heavy lifting of finding format modules.
     """
     if check_for_language(lang):
-        format_locations = ['django.conf.locale.%s']
-        if format_module_path:
-            format_locations.append(format_module_path + '.%s')
-            format_locations.reverse()
+        format_locations = []
+        if settings.FORMAT_MODULE_PATH:
+            if isinstance(settings.FORMAT_MODULE_PATH, six.string_types):
+                format_module_path_setting = [settings.FORMAT_MODULE_PATH]
+            else:
+                format_module_path_setting = settings.FORMAT_MODULE_PATH
+            for path in format_module_path_setting:
+                format_locations.append(path + '.%s')
+        format_locations.append('django.conf.locale.%s')
         locale = to_locale(lang)
         locales = [locale]
         if '_' in locale:

docs/ref/settings.txt

@@ -1378,6 +1378,20 @@ like::
                 __init__.py
                 formats.py
 
+.. versionchanged:: 1.8
+
+    You can also set this setting to a list of Python paths, for example::
+
+        FORMAT_MODULE_PATH = [
+            'mysite.formats',
+            'some_app.formats',
+        ]
+
+    When Django searches for a certain format, it will go through all given
+    Python paths until it finds a module that actually defines the given
+    format. This means that formats defined in packages farther up in the list
+    will take precedence over the same formats in packages farther down.
+
 Available formats are :setting:`DATE_FORMAT`, :setting:`TIME_FORMAT`,
 :setting:`DATETIME_FORMAT`, :setting:`YEAR_MONTH_FORMAT`,
 :setting:`MONTH_DAY_FORMAT`, :setting:`SHORT_DATE_FORMAT`,

docs/releases/1.8.txt

@@ -133,7 +133,10 @@ Forms
 Internationalization
 ^^^^^^^^^^^^^^^^^^^^
 
-* ...
+* :setting:`FORMAT_MODULE_PATH` can now be a list of strings representing
+  module paths. This allows importing several format modules from different
+  reusable apps. It also allows overriding those custom formats in your main
+  Django project.
 
 Management Commands
 ^^^^^^^^^^^^^^^^^^^

docs/topics/i18n/formatting.txt

@@ -154,11 +154,20 @@ Django provides format definitions for many locales, but sometimes you might
 want to create your own, because a format files doesn't exist for your locale,
 or because you want to overwrite some of the values.
 
-To use custom formats, specify the path where you'll place format files first.
-To do that, just set your :setting:`FORMAT_MODULE_PATH` setting to the package
-where format files will exist, for instance::
 
-    FORMAT_MODULE_PATH = 'mysite.formats'
+.. versionchanged:: 1.8
+
+    The ability to specify FORMAT_MODULE_PATH as a list was added. Previously,
+    only a single string value was supported.
+
+To use custom formats, specify the path where you'll place format files
+first. To do that, just set your :setting:`FORMAT_MODULE_PATH` setting to
+the package where format files will exist, for instance::
+
+    FORMAT_MODULE_PATH = [
+        'mysite.formats',
+        'some_app.formats',
+    ]
 
 Files are not placed directly in this directory, but in a directory named as
 the locale, and must be named ``formats.py``.

tests/utils_tests/test_formats.py

@@ -0,0 +1,59 @@
+"""Tests for ``django/utils/formats.py``."""
+from django.test import TestCase
+from django.utils.formats import iter_format_modules
+
+
+class IterFormatModulesTestCase(TestCase):
+    """Tests for the ``iter_format_modules`` method."""
+    longMessage = True
+
+    def test_returns_correct_default(self):
+        """
+        Should return default module when FORMAT_MODULE_PATH is not set.
+        """
+        result = list(iter_format_modules('en'))
+        self.assertEqual(len(result), 1, msg=(
+            "Should return only Django's default formats module."))
+        self.assertEqual(
+            result[0].__name__, 'django.conf.locale.en.formats', msg=(
+                'Should have added the language to the module path'))
+
+    def test_with_setting_as_basestring(self):
+        """
+        Before ticket #20477 FORMAT_MODULE_PATH was supposed to be a string.
+
+        This test ensures backwards compatibility.
+        """
+        with self.settings(
+                FORMAT_MODULE_PATH='utils_tests.test_module.formats'):
+            result = list(iter_format_modules('en'))
+            self.assertEqual(len(result), 2, msg=(
+                'Should return both, the default value and the one from the'
+                ' setting'))
+            self.assertEqual(
+                result[0].__name__,
+                'utils_tests.test_module.formats.en.formats',
+                msg=('Should return the module from the setting first and'
+                     ' should have added the language to the module path'))
+
+    def test_with_setting_as_list_of_strings(self):
+        """
+        After ticket #20477 FORMAT_MODULE_PATH can also be a list of strings.
+
+        This tests verifies the new functionality.
+        """
+        FORMAT_MODULE_PATH = [
+            'utils_tests.test_module.formats',
+            'utils_tests.test_module.formats2',
+        ]
+        with self.settings(
+                FORMAT_MODULE_PATH=FORMAT_MODULE_PATH):
+            result = list(iter_format_modules('en'))
+            self.assertEqual(len(result), 3, msg=(
+                'Should return the default value and the two values from the'
+                ' setting'))
+            self.assertEqual(
+                result[0].__name__,
+                'utils_tests.test_module.formats.en.formats',
+                msg=('Should return the values from the setting and add the'
+                     ' language to the module path'))

tests/utils_tests/test_module/formats/__init__.py

@@ -0,0 +1,4 @@
+"""
+Custom format module. Used by tests in ``tests/utils_tests/test_formats.py``.
+
+"""