OSCAR_SLUG_FUNCTION: Support string notation to set slugifier

Importing things in settings is discouraged. But until now,
OSCAR_SLUG_FUNCTION could only be set as a callable, which requires
importing. It's now been updated to use the import_string function.

docs/source/ref/settings.rst

@@ -158,7 +158,7 @@ A list of dashboard navigation elements. Usage is explained in
 ``OSCAR_DASHBOARD_DEFAULT_ACCESS_FUNCTION``
 -------------------------------------------
 
-Default: ``oscar.apps.dashboard.nav.default_access_fn``
+Default: ``'oscar.apps.dashboard.nav.default_access_fn'``
 
 ``OSCAR_DASHBOARD_NAVIGATION`` allows passing an access function for each node
 which is used to determine whether to show the node for a specific user or not.
@@ -452,17 +452,22 @@ stripped.  For instance::
 ``OSCAR_SLUG_FUNCTION``
 -----------------------
 
-Default: ``django.template.defaultfilters.slugify``
+Default: ``'oscar.core.utils.default_slugifier'``
 
 The slugify function to use.  Note that is used within Oscar's slugify wrapper
-(in ``oscar.core.utils``) which applies the custom map and blacklist.
+(in ``oscar.core.utils``) which applies the custom map and blacklist. String
+notation is recommended, but specifying a callable is supported for
+backwards-compatibility.
 
 Example::
 
+    # in myproject.utils
     def some_slugify(value)
         pass
 
-    OSCAR_SLUG_FUNCTION = some_slugify
+    # in settings.py
+    OSCAR_SLUG_FUNCTION = 'myproject.utils.some_slugify'
+
 
 ``OSCAR_SLUG_BLACKLIST``
 ------------------------

docs/source/releases/v0.8.rst

@@ -101,6 +101,8 @@ Minor changes
   forgotten when adding tracking of the Python and Django version in 0.7.
   Total information collected now is the versions of Django, Python and Oscar.
 
+* ``OSCAR_SLUG_FUNCTION`` now accepts both string notation and a callable.
+
 Bugfixes
 ~~~~~~~~
 

oscar/core/utils.py

@@ -1,11 +1,23 @@
-from __future__ import absolute_import  # for import below
-import six
+from __future__ import absolute_import  # for logging import below
 import logging
+import six
 
 from django.utils.timezone import get_current_timezone, is_naive, make_aware
-from unidecode import unidecode
 from django.conf import settings
-from django.template.defaultfilters import date as date_filter
+from django.template.defaultfilters import (date as date_filter,
+                                            slugify as django_slugify)
+from unidecode import unidecode
+
+from oscar.core.loading import import_string
+
+
+def default_slugifier(value):
+    """
+    Oscar's default slugifier function.
+    Uses Django's slugify function, but first applies unidecode() to convert
+    non-ASCII strings to ASCII equivalents where possible.
+    """
+    return django_slugify(value)
 
 
 def slugify(value):
@@ -18,11 +30,10 @@ def slugify(value):
         value = value.replace(k, v)
 
     # Allow an alternative slugify function to be specified
-    if hasattr(settings, 'OSCAR_SLUG_FUNCTION'):
-        slugifier = settings.OSCAR_SLUG_FUNCTION
-    else:
-        from django.template import defaultfilters
-        slugifier = defaultfilters.slugify
+    # Recommended way to specify a function is as a string
+    slugifier = getattr(settings, 'OSCAR_SLUG_FUNCTION', default_slugifier)
+    if isinstance(slugifier, six.string_types):
+        slugifier = import_string(slugifier)
 
     # Use unidecode to convert non-ASCII strings to ASCII equivalents where
     # possible.

tests/unit/core/utils_tests.py

@@ -1,8 +1,11 @@
+# coding=utf-8
 from django.test import TestCase
 from django.test.utils import override_settings
 
 from oscar.core import utils
 
+sluggish = lambda s: s.upper()
+
 
 class TestSlugify(TestCase):
 
@@ -15,3 +18,12 @@ class TestSlugify(TestCase):
         blacklist = ['the']
         with override_settings(OSCAR_SLUG_BLACKLIST=blacklist):
             self.assertEqual('bible', utils.slugify('The Bible'))
+
+    def test_handles_unicode(self):
+        self.assertEqual('konig-der-strasse',
+                         utils.slugify(u'König der Straße'))
+
+    def test_works_with_custom_slugifier(self):
+        for fn in [sluggish, 'tests.unit.core.utils_tests.sluggish']:
+            with override_settings(OSCAR_SLUG_FUNCTION=fn):
+                self.assertEqual('HAM AND EGGS', utils.slugify('Ham and eggs'))