Add heal category trees utils (#1809)

misago/categories/delete.py

@@ -0,0 +1,5 @@
+from .models import Category
+
+
+def delete_category(category: Category):
+    category.delete()

misago/categories/management/commands/healcategorytrees.py

@@ -0,0 +1,30 @@
+from django.core.management.base import BaseCommand
+
+from ....acl.cache import clear_acl_cache
+from ....cache.enums import CacheName
+from ....cache.versions import invalidate_cache
+from ...mptt import heal_category_trees
+
+
+class Command(BaseCommand):
+    """
+    This command rebuilds the category trees in the database.
+    
+    It's useful when the MPTT data of one or more categories becomes invalid,
+    either due to a bug or manual database manipulation.
+    """
+
+    help = "Heals the category trees in the database"
+
+    def handle(self, *args, **options):
+        heal_category_trees()
+        self.stdout.write("Rebuild category trees in the database.")
+
+        invalidate_cache(
+            CacheName.CATEGORIES,
+            CacheName.MODERATORS,
+            CacheName.PERMISSIONS,
+        )
+
+        clear_acl_cache()
+        self.stdout.write("Cleared caches associated with category trees.")

misago/categories/migrations/0002_default_categories.py

@@ -23,8 +23,8 @@ def create_default_categories_tree(apps, schema_editor):
         special_role="root_category",
         name="Root",
         slug="root",
-        lft=3,
-        rght=6,
+        lft=1,
+        rght=4,
         tree_id=CategoryTreeDeprecated.THREADS,
         level=0,
     )
@@ -33,8 +33,8 @@ def create_default_categories_tree(apps, schema_editor):
 
     Category.objects.create(
         parent=root,
-        lft=4,
-        rght=5,
+        lft=2,
+        rght=3,
         tree_id=CategoryTreeDeprecated.THREADS,
         level=1,
         name=category_name,

misago/categories/mptt.py

@@ -0,0 +1,72 @@
+from .models import Category
+
+MPTTData = tuple[int, int, int]
+
+
+def heal_category_trees() -> int:
+    trees: set[int] = set()
+    categories: dict[int, dict] = {}
+
+    queryset = Category.objects.values(
+        "id",
+        "parent_id",
+        "tree_id",
+        "level",
+        "lft",
+        "rght",
+    ).order_by("tree_id", "lft")
+
+    for category in queryset:
+        trees.add(category["tree_id"])
+        categories[category["id"]] = category
+
+    healthy_categories: list[dict] = []
+    for tree_id in trees:
+        healthy_categories += heal_tree(tree_id, categories)
+
+    updates = 0
+    for healed_category in healthy_categories:
+        org_category = categories[healed_category["id"]]
+        if org_category != healed_category:
+            Category.objects.filter(id=healed_category["id"]).update(
+                level=healed_category["level"],
+                lft=healed_category["lft"],
+                rght=healed_category["rght"],
+            )
+            updates += 1
+
+    return updates
+
+
+def heal_tree(tree_id: int, categories: dict[int, dict]) -> list[dict]:
+    tree_categories = {
+        c["id"]: c.copy() for c in categories.values() if c["tree_id"] == tree_id
+    }
+    tree_categories_list = list(tree_categories.values())
+
+    cursor = 0
+    for category in tree_categories_list:
+        if category["parent_id"]:
+            continue
+
+        category["level"] = 0
+        cursor += 1
+        category["lft"] = cursor
+        category["rght"] = cursor = heal_category(category, tree_categories_list) + 1
+
+    return sorted(tree_categories_list, key=lambda i: i["lft"])
+
+
+def heal_category(category: dict, tree_categories_list: list[dict]) -> int:
+    cursor = category["lft"]
+    for child in tree_categories_list:
+        if child["parent_id"] != category["id"]:
+            continue
+
+        child["level"] = category["level"] + 1
+
+        cursor += 1
+        child["lft"] = cursor
+        child["rght"] = cursor = heal_category(child, tree_categories_list) + 1
+
+    return cursor