Verify that tree_queries has been added to INSTALLED_APPS when using TreeAdmin

Author: matthiask

CHANGELOG.rst

@@ -10,6 +10,8 @@ Next version
 - Added an example migration to the documentation for migrating from
   django-mptt to django-tree-queries. Thanks to @felixmm for providing this!
 - Avoided fetching ancestors of nodes without parents. Thanks to @felixmm!
+- Added a system check which verifies that ``"tree_queries"`` has been added to
+  ``INSTALLED_APPS`` if using the ``TreeAdmin`` model admin class.
 
 
 0.21 (2025-09-16)

tree_queries/admin.py

@@ -1,9 +1,14 @@
 import json
 
 from django import forms
-from django.contrib import messages
+from django.conf import settings
+from django.contrib import admin, messages
 from django.contrib.admin import ModelAdmin, SimpleListFilter, display, helpers
-from django.contrib.admin.options import IncorrectLookupParameters, csrf_protect_m
+from django.contrib.admin.options import (
+    IncorrectLookupParameters,
+    csrf_protect_m,
+)
+from django.core import checks
 from django.core.exceptions import ValidationError
 from django.db.models import F
 from django.http import HttpResponse
@@ -58,6 +63,18 @@ class NodeAdmin(TreeAdmin):
     list_display = ["collapse_column", "indented_title", "move_column"]
     list_display_links = ["indented_title"]
 
+    def check(self, **kwargs):
+        errors = super().check(**kwargs)
+        if "tree_queries" not in settings.INSTALLED_APPS:
+            errors.append(
+                checks.Error(
+                    '"tree_queries" must be in INSTALLED_APPS.',
+                    obj=self.__class__,
+                    id="tree_queries.E001",
+                )
+            )
+        return errors
+
     @csrf_protect_m
     def changelist_view(self, request, **kwargs):
         from js_asset.js import JS  # noqa: PLC0415
@@ -120,6 +137,7 @@ def indented_title(self, instance, *, ellipsize=True):
 
     indented_title.short_description = _("title")
 
+    @admin.display(description=_("move"))
     def move_column(self, instance):
         """
         Show a ``move`` link which leads to a separate page where the move
@@ -165,8 +183,6 @@ def move_column(self, instance):
             options,
         )
 
-    move_column.short_description = _("move")
-
     def get_urls(self):
         """
         Add our own ``move`` view.