dont restore objects that have missing dependencies

src/c3nav/editor/models/changedobject.py

@@ -253,6 +253,40 @@ class ChangedObject(models.Model):
                 return False
         return True
 
+    def can_restore(self, force_query=False):
+        if not self.deleted:
+            return False
+        for field in self.model_class._meta.get_fields():
+            if not field.many_to_one:
+                continue
+            if field.name not in self.updated_fields:
+                continue
+            related_model = field.related_model
+            if related_model._meta.app_label != 'mapdata':
+                continue
+
+            pk = self.updated_fields[field.name]
+
+            if force_query:
+                # query here to avoid a race condition
+                related_content_type = ContentType.objects.get_for_model(related_model)
+                qs = self.changeset.changed_objects_set.filter(content_type=related_content_type)
+                if is_created_pk(pk):
+                    if not qs.filter(pk=int(pk[2:]), deleted=False).exists():
+                        return False
+                else:
+                    if qs.filter(existing_object_pk=pk, deleted=True).exists():
+                        return False
+            else:
+                if is_created_pk(pk):
+                    if pk not in self.changeset.created_objects.get(related_model, ()):
+                        return False
+                else:
+                    if pk in self.changeset.deleted_existing.get(related_model, ()):
+                        return False
+
+        return True
+
     def mark_deleted(self):
         if not self.can_delete():
             return False
@@ -310,6 +344,10 @@ class ChangedObject(models.Model):
         self._m2m_added_cache.setdefault(name, set()).difference_update(pks)
         self.m2m_set(name)
 
+    def restore(self):
+        self.deleted = False
+        self.save(standalone=True)
+
     @property
     def does_something(self):
         return (self.updated_fields or self._m2m_added_cache or self._m2m_removed_cache or self.is_created or

src/c3nav/editor/templates/editor/changeset.html

@@ -90,7 +90,7 @@
                         <a class="btn btn-default btn-xs pull-right" data-force-next-zoom href="{{ obj.edit_url }}">
                             {% trans 'Edit' %}
                         </a>
-                    {% elif obj.deleted and can_edit %}
+                    {% elif obj.deleted and can_edit and obj.can_restore %}
                         <button type="submit" name="restore" value="{{ obj.pk }}" class="btn btn-warning btn-xs pull-right">
                             {% trans 'Restore' %}
                         </button>

src/c3nav/editor/views/changes.py

@@ -43,10 +43,12 @@ def changeset_detail(request, pk):
                     except:
                         pass
                     else:
-                        if changed_object.deleted:
-                            changed_object.deleted = False
-                            changed_object.save(standalone=True)
-                        messages.success(request, _('Object has been successfully restored.'))
+                        if changed_object.can_restore(force_query=True):
+                            changed_object.restore()
+                            messages.success(request, _('Object has been successfully restored.'))
+                        else:
+                            messages.error(request, _('You cannot restore this object, because '
+                                                      'it depends on a deleted object.'))
                 else:
                     messages.error(request, _('You can not edit changes on this change set.'))
 
@@ -235,6 +237,7 @@ def changeset_detail(request, pk):
                 'changes': changes,
                 'edit_url': edit_url,
                 'deleted': changed_object.deleted,
+                'can_restore': changed_object.can_restore(),
                 'order': (changed_object.deleted and changed_object.is_created, not changed_object.is_created),
             }
             changed_objects_data.append(changed_object_data)