check unique collisions to prevent those objects from being restored

src/c3nav/editor/models/changedobject.py

@@ -273,6 +273,25 @@ class ChangedObject(models.Model):
                 return False
         return True
 
+    def get_unique_collisions(self, max_one=False):
+        result = set()
+        if not self.deleted:
+            return result
+        uniques = tuple(self.model_class._meta.unique_together)
+        uniques += tuple((field.name, )
+                         for field in self.model_class._meta.get_fields() if field.unique and not field.primary_key)
+        for unique in uniques:
+            names = tuple((name if self.model_class._meta.get_field(name).related_model is None else name+'__pk')
+                          for name in unique)
+            values = tuple(getattr(self.obj, self.model_class._meta.get_field(name).attname) for name in unique)
+            if None in values:
+                continue
+            if self.changeset.wrap_model(self.model_class).objects.filter(**dict(zip(names, values))).exists():
+                result |= set(unique)
+                if result and max_one:
+                    return result
+        return result
+
     def get_missing_dependencies(self, force_query=False, max_one=False):
         result = set()
         if not self.deleted:
@@ -371,7 +390,7 @@ class ChangedObject(models.Model):
     def restore(self):
         if self.deleted is False:
             return
-        if self.get_missing_dependencies(force_query=True, max_one=True):
+        if self.get_missing_dependencies(force_query=True, max_one=True) or self.get_unique_collisions(max_one=True):
             raise PermissionError
         self.deleted = False
         self.save(standalone=True)

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 and not obj.missing_dependencies %}
+                    {% elif obj.deleted and can_edit and not obj.missing_dependencies and not obj.unique_collisions %}
                         <button type="submit" name="restore" value="{{ obj.pk }}" class="btn btn-warning btn-xs pull-right">
                             {% trans 'Restore' %}
                         </button>
@@ -108,7 +108,7 @@
                 <tr>
                     <td class="text-{{ change.class }}"><i class="glyphicon glyphicon-{{ change.icon }}"></i></td>
                     <td{% if obj.deleted and change.icon != 'minus' %} class="text-muted"{% endif %}>
-                        {% if change.missing_dependency %}<i class="glyphicon glyphicon-alert pull-right text-warning"></i>{% endif %}
+                        {% if change.missing_dependency or change.unique_collision %}<i class="glyphicon glyphicon-alert pull-right text-warning"></i>{% endif %}
                         {% if change.empty %}<em>{% else %}<u>{% endif %}{{ change.title }}{% if not change.empty %}</u>:{% else %}</em>{% endif %}
                         {{ change.value }}
                     </td>

src/c3nav/editor/views/changes.py

@@ -48,8 +48,8 @@ def changeset_detail(request, pk):
                             changed_object.restore()
                             messages.success(request, _('Object has been successfully restored.'))
                         except PermissionError:
-                            messages.error(request, _('You cannot restore this object, because '
+                            messages.error(request, _('You cannot restore this object, because it depends on '
-                                                      'it depends on a deleted object.'))
+                                                      'a deleted object or it would violate a unique contraint.'))
 
                 else:
                     messages.error(request, _('You can not edit changes on this change set.'))
@@ -234,6 +234,7 @@ def changeset_detail(request, pk):
 
             changes = []
             missing_dependencies = changed_object.get_missing_dependencies()
+            unique_collisions = changed_object.get_unique_collisions()
             changed_object_data = {
                 'model': obj.__class__,
                 'model_title': obj.__class__._meta.verbose_name,
@@ -244,6 +245,7 @@ def changeset_detail(request, pk):
                 'edit_url': edit_url,
                 'deleted': changed_object.deleted,
                 'missing_dependencies': missing_dependencies,
+                'unique_collisions': unique_collisions,
                 'order': (changed_object.deleted and changed_object.is_created, not changed_object.is_created),
             }
             changed_objects_data.append(changed_object_data)
@@ -293,6 +295,10 @@ def changeset_detail(request, pk):
                             change_data.update({
                                 'missing_dependency': field.name in missing_dependencies,
                             })
+                        if name in unique_collisions:
+                            change_data.update({
+                                'unique_collision': field.name in unique_collisions,
+                            })
                         order = 5
                         if name == 'slug':
                             order = 1