Fixed #21113 -- Made LogEntry.change_message language independent

Thanks Tim Graham for the review.

django/contrib/admin/models.py

@@ -1,5 +1,7 @@
 from __future__ import unicode_literals
 
+import json
+
 from django.conf import settings
 from django.contrib.admin.utils import quote
 from django.contrib.contenttypes.models import ContentType
@@ -7,6 +9,7 @@ from django.db import models
 from django.urls import NoReverseMatch, reverse
 from django.utils import timezone
 from django.utils.encoding import python_2_unicode_compatible, smart_text
+from django.utils.text import get_text_list
 from django.utils.translation import ugettext, ugettext_lazy as _
 
 ADDITION = 1
@@ -18,6 +21,8 @@ class LogEntryManager(models.Manager):
     use_in_migrations = True
 
     def log_action(self, user_id, content_type_id, object_id, object_repr, action_flag, change_message=''):
+        if isinstance(change_message, list):
+            change_message = json.dumps(change_message)
         self.model.objects.create(
             user_id=user_id,
             content_type_id=content_type_id,
@@ -50,6 +55,7 @@ class LogEntry(models.Model):
     # Translators: 'repr' means representation (https://docs.python.org/3/library/functions.html#repr)
     object_repr = models.CharField(_('object repr'), max_length=200)
     action_flag = models.PositiveSmallIntegerField(_('action flag'))
+    # change_message is either a string or a JSON structure
     change_message = models.TextField(_('change message'), blank=True)
 
     objects = LogEntryManager()
@@ -69,7 +75,7 @@ class LogEntry(models.Model):
         elif self.is_change():
             return ugettext('Changed "%(object)s" - %(changes)s') % {
                 'object': self.object_repr,
-                'changes': self.change_message,
+                'changes': self.get_change_message(),
             }
         elif self.is_deletion():
             return ugettext('Deleted "%(object)s."') % {'object': self.object_repr}
@@ -85,6 +91,46 @@ class LogEntry(models.Model):
     def is_deletion(self):
         return self.action_flag == DELETION
 
+    def get_change_message(self):
+        """
+        If self.change_message is a JSON structure, interpret it as a change
+        string, properly translated.
+        """
+        if self.change_message and self.change_message[0] == '[':
+            try:
+                change_message = json.loads(self.change_message)
+            except ValueError:
+                return self.change_message
+            messages = []
+            for sub_message in change_message:
+                if 'added' in sub_message:
+                    if sub_message['added']:
+                        sub_message['added']['name'] = ugettext(sub_message['added']['name'])
+                        messages.append(ugettext('Added {name} "{object}".').format(**sub_message['added']))
+                    else:
+                        messages.append(ugettext('Added.'))
+
+                elif 'changed' in sub_message:
+                    sub_message['changed']['fields'] = get_text_list(
+                        sub_message['changed']['fields'], ugettext('and')
+                    )
+                    if 'name' in sub_message['changed']:
+                        sub_message['changed']['name'] = ugettext(sub_message['changed']['name'])
+                        messages.append(ugettext('Changed {fields} for {name} "{object}".').format(
+                            **sub_message['changed']
+                        ))
+                    else:
+                        messages.append(ugettext('Changed {fields}.').format(**sub_message['changed']))
+
+                elif 'deleted' in sub_message:
+                    sub_message['deleted']['name'] = ugettext(sub_message['deleted']['name'])
+                    messages.append(ugettext('Deleted {name} "{object}".').format(**sub_message['deleted']))
+
+            change_message = ' '.join(msg[0].upper() + msg[1:] for msg in messages)
+            return change_message or ugettext('No fields changed.')
+        else:
+            return self.change_message
+
     def get_edited_object(self):
         "Returns the edited object represented by this log entry"
         return self.content_type.get_object_for_this_type(pk=self.object_id)

django/contrib/admin/options.py

@@ -44,7 +44,9 @@ from django.utils.html import escape, format_html
 from django.utils.http import urlencode, urlquote
 from django.utils.safestring import mark_safe
 from django.utils.text import capfirst, get_text_list
-from django.utils.translation import string_concat, ugettext as _, ungettext
+from django.utils.translation import (
+    override as translation_override, string_concat, ugettext as _, ungettext,
+)
 from django.views.decorators.csrf import csrf_protect
 from django.views.generic import RedirectView
 
@@ -924,33 +926,44 @@ class ModelAdmin(BaseModelAdmin):
                 return urlencode({'_changelist_filters': preserved_filters})
         return ''
 
+    @translation_override(None)
     def construct_change_message(self, request, form, formsets, add=False):
         """
-        Construct a change message from a changed object.
+        Construct a JSON structure describing changes from a changed object.
+        Translations are deactivated so that strings are stored untranslated.
+        Translation happens later on LogEntry access.
         """
         change_message = []
         if add:
-            change_message.append(_('Added.'))
+            change_message.append({'added': {}})
         elif form.changed_data:
-            change_message.append(_('Changed %s.') % get_text_list(form.changed_data, _('and')))
+            change_message.append({'changed': {'fields': form.changed_data}})
 
         if formsets:
             for formset in formsets:
                 for added_object in formset.new_objects:
-                    change_message.append(_('Added %(name)s "%(object)s".')
-                                          % {'name': force_text(added_object._meta.verbose_name),
-                                             'object': force_text(added_object)})
+                    change_message.append({
+                        'added': {
+                            'name': force_text(added_object._meta.verbose_name),
+                            'object': force_text(added_object),
+                        }
+                    })
                 for changed_object, changed_fields in formset.changed_objects:
-                    change_message.append(_('Changed %(list)s for %(name)s "%(object)s".')
-                                          % {'list': get_text_list(changed_fields, _('and')),
-                                             'name': force_text(changed_object._meta.verbose_name),
-                                             'object': force_text(changed_object)})
+                    change_message.append({
+                        'changed': {
+                            'name': force_text(changed_object._meta.verbose_name),
+                            'object': force_text(changed_object),
+                            'fields': changed_fields,
+                        }
+                    })
                 for deleted_object in formset.deleted_objects:
-                    change_message.append(_('Deleted %(name)s "%(object)s".')
-                                          % {'name': force_text(deleted_object._meta.verbose_name),
-                                             'object': force_text(deleted_object)})
-        change_message = ' '.join(change_message)
-        return change_message or _('No fields changed.')
+                    change_message.append({
+                        'deleted': {
+                            'name': force_text(deleted_object._meta.verbose_name),
+                            'object': force_text(deleted_object),
+                        }
+                    })
+        return change_message
 
     def message_user(self, request, message, level=messages.INFO, extra_tags='',
                      fail_silently=False):

django/contrib/admin/templates/admin/object_history.html

@@ -29,7 +29,7 @@
         <tr>
             <th scope="row">{{ action.action_time|date:"DATETIME_FORMAT" }}</th>
             <td>{{ action.user.get_username }}{% if action.user.get_full_name %} ({{ action.user.get_full_name }}){% endif %}</td>
-            <td>{{ action.change_message }}</td>
+            <td>{{ action.get_change_message }}</td>
         </tr>
         {% endfor %}
         </tbody>