#141: patch Slug Field pre_save() to ensure slug value consistency

runtests.py

@@ -61,6 +61,7 @@ def runtests():
                 ('en', 'English'),
             ),
             MIDDLEWARE_CLASSES=(),
+            WAGTAILMODELTRANSLATION_ORIGINAL_SLUG_LANGUAGE='default',
         )
 
     if django.VERSION >= (1, 7):

wagtail_modeltranslation/patch_wagtailadmin.py

@@ -2,7 +2,7 @@
 import copy
 import logging
 
-from django.core.exceptions import ValidationError
+from django.core.exceptions import ValidationError, FieldDoesNotExist
 from django.core.urlresolvers import reverse
 from django.db import transaction
 from django.http import Http404
@@ -23,7 +23,7 @@ from wagtail.wagtailsearch.index import SearchField
 from wagtail.wagtailsnippets.models import get_snippet_models
 from wagtail.wagtailsnippets.views.snippets import SNIPPET_EDIT_HANDLERS
 
-from wagtail_modeltranslation.settings import CUSTOM_SIMPLE_PANELS, CUSTOM_COMPOSED_PANELS
+from wagtail_modeltranslation.settings import CUSTOM_SIMPLE_PANELS, CUSTOM_COMPOSED_PANELS, ORIGINAL_SLUG_LANGUAGE
 from wagtail_modeltranslation.utils import compare_class_tree_depth
 
 logger = logging.getLogger('wagtail.core')
@@ -88,8 +88,15 @@ class WagtailTranslator(object):
                     translated_field.field_name = build_localized_fieldname(field.field_name, language)
                     model.search_fields = list(model.search_fields) + [translated_field]
 
-        # OVERRIDE PAGE METHODS
+        # SLUG FIELD PATCHING
 
+        try:
+            slug_field = model._meta.get_field('slug')
+            _patch_pre_save(slug_field)
+        except FieldDoesNotExist:
+            pass
+
+        # OVERRIDE PAGE METHODS
         model.move = _new_move
         model.set_url_path = _new_set_url_path
         model.route = _new_route
@@ -201,7 +208,6 @@ class WagtailTranslator(object):
         # patched, leaving the original untouched
         return panel
 
-
 # Overridden Page methods adapted to the translated fields
 
 @transaction.atomic  # only commit when all descendants are properly updated
@@ -403,6 +409,30 @@ def _patch_clean(model):
     model.clean = clean
 
 
+def _patch_pre_save(field):
+    if not ORIGINAL_SLUG_LANGUAGE:
+        return
+
+    if ORIGINAL_SLUG_LANGUAGE == 'default':
+        reference_slug_language = mt_settings.DEFAULT_LANGUAGE
+    else:
+        reference_slug_language = ORIGINAL_SLUG_LANGUAGE
+
+    def pre_save(self, model_instance, add):
+        """
+        Returns slug field's value using the language set by `WAGTAILMODELTRANSLATION_ORIGINAL_SLUG_LANGUAGE`
+        just before saving.
+        """
+        current_language = get_language()
+        # using ORIGINAL_SLUG_LANGUAGE makes Page's slug value consistent
+        trans_real.activate(reference_slug_language)
+        value = getattr(model_instance, self.attname)
+        trans_real.activate(current_language)
+        return value
+
+    field.pre_save = pre_save.__get__(field)
+
+
 def patch_wagtail_models():
     # After all models being registered the Page or BaseSetting subclasses and snippets are patched
     registered_models = translator.get_registered_models()

wagtail_modeltranslation/settings.py

@@ -10,3 +10,5 @@ CUSTOM_SIMPLE_PANELS = [import_from_string(panel_class) for panel_class in
                         getattr(settings, 'WAGTAILMODELTRANSLATION_CUSTOM_SIMPLE_PANELS', [])]
 CUSTOM_COMPOSED_PANELS = [import_from_string(panel_class) for panel_class in
                           getattr(settings, 'WAGTAILMODELTRANSLATION_CUSTOM_COMPOSED_PANELS', [])]
+
+ORIGINAL_SLUG_LANGUAGE = getattr(settings, 'WAGTAILMODELTRANSLATION_ORIGINAL_SLUG_LANGUAGE', None)