🐛(back) check title unicity when renaming an existing one

An item title can be updated. Check title unicity constraint on this
case.

src/backend/core/api/serializers.py

@@ -255,6 +255,23 @@ class ItemSerializer(ListItemSerializer):
     def create(self, validated_data):
         raise NotImplementedError("Create method can not be used.")
 
+    def update(self, instance, validated_data):
+        """Validate that the title is unique in the current path."""
+        if (
+            instance.title != validated_data.get("title")
+            and instance.depth > 1
+            and instance.is_item_title_existing(validated_data.get("title"))
+        ):
+            raise serializers.ValidationError(
+                {
+                    "title": _(
+                        "An item with this title already exists in the current path."
+                    )
+                }
+            )
+
+        return super().update(instance, validated_data)
+
 
 class CreateItemSerializer(ItemSerializer):
     """Serializer used to create a new item"""

src/backend/core/models.py

@@ -417,6 +417,20 @@ class ItemQuerySet(TreeQuerySet):
         return self.filter(models.Q(link_reach=LinkReachChoices.PUBLIC))
 
 
+def _is_item_title_existing(queryset, title):
+    """Check if the title is unique in the same path."""
+    return (
+        queryset.filter(title=title)
+        .filter(
+            models.Q(
+                models.Q(deleted_at__isnull=True)
+                | models.Q(ancestors_deleted_at__isnull=True)
+            )
+        )
+        .exists()
+    )
+
+
 class ItemManager(TreeManager):
     """Custom manager for Item model overriding create_child method."""
 
@@ -440,16 +454,9 @@ class ItemManager(TreeManager):
             if parent.type != ItemTypeChoices.FOLDER:
                 raise ValidationError({"type": _("Only folders can have children.")})
 
-            if (
-                self.children(parent.path)
-                .filter(title=kwargs.get("title"))
-                .filter(
-                    models.Q(
-                        models.Q(deleted_at__isnull=True)
-                        | models.Q(ancestors_deleted_at__isnull=True)
-                    )
-                )
-                .exists()
+            if _is_item_title_existing(
+                self.children(parent.path),
+                kwargs.get("title"),
             ):
                 raise ValidationError(
                     {"title": _("title already exists in this folder.")}
@@ -603,6 +610,13 @@ class Item(TreeModel, BaseModel):
         """Generate a unique cache key for each item."""
         return f"item_{self.id!s}_nb_accesses"
 
+    def is_item_title_existing(self, title):
+        """Check if the title is unique in the same path."""
+        return _is_item_title_existing(
+            self.siblings(),
+            title,
+        )
+
     @property
     def nb_accesses(self):
         """Calculate the number of accesses."""

src/backend/core/tests/items/test_api_items_update.py

@@ -351,3 +351,65 @@ def test_api_items_update_administrator_or_owner_of_another(via, mock_user_teams
     other_item.refresh_from_db()
     other_item_values = serializers.ItemSerializer(instance=other_item).data
     assert other_item_values == old_item_values
+
+
+def test_api_items_update_title_unique_in_current_path():
+    """
+    The title of an item should be unique in the current path.
+    """
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    root = factories.ItemFactory(
+        title="item1", type=models.ItemTypeChoices.FOLDER, users=[user]
+    )
+    child = factories.ItemFactory(
+        title="child1", type=models.ItemTypeChoices.FOLDER, parent=root, users=[user]
+    )
+
+    factories.ItemFactory(
+        title="child2", type=models.ItemTypeChoices.FOLDER, parent=root, users=[user]
+    )
+
+    # update child1 to rename it to child2 should fails
+    response = client.put(
+        f"/api/v1.0/items/{child.id!s}/",
+        {"title": "child2"},
+        format="json",
+    )
+    assert response.status_code == 400
+    assert response.json() == {
+        "title": "An item with this title already exists in the current path."
+    }
+
+
+def test_api_items_update_title_unique_in_current_path_soft_deleted():
+    """
+    Reusing a title of a soft-deleted item should be allowed.
+    """
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    root = factories.ItemFactory(
+        title="item1", type=models.ItemTypeChoices.FOLDER, users=[user]
+    )
+    child = factories.ItemFactory(
+        title="child1", type=models.ItemTypeChoices.FOLDER, parent=root, users=[user]
+    )
+    child.soft_delete()
+
+    child2 = factories.ItemFactory(
+        title="child2", type=models.ItemTypeChoices.FOLDER, parent=root, users=[user]
+    )
+
+    # update child 2 title using child 1 title is allowed
+    response = client.put(
+        f"/api/v1.0/items/{child2.id!s}/",
+        {"title": "child1"},
+        format="json",
+    )
+    assert response.status_code == 200