Add a check for the use of PGViewsAutodetector

Author: mikicz

django_pgviews/apps.py

@@ -47,6 +47,8 @@ def ready(self) -> None:
         """
         from django.conf import settings
 
+        from .checks import validate_has_pgviews_autodetector  # noqa
+
         sync_enabled = getattr(settings, "MATERIALIZED_VIEWS_DISABLE_SYNC_ON_MIGRATE", False) is False
 
         if sync_enabled:

django_pgviews/checks.py

@@ -0,0 +1,41 @@
+from typing import Any
+
+from django.core.checks import CheckMessage, Tags, register
+from django.core.checks import Warning as CheckWarning
+
+from django_pgviews.db.migrations.autodetector import PGViewsAutodetector
+
+
+@register(Tags.database)  # type: ignore[not-callable]
+def validate_has_pgviews_autodetector(**kwargs: Any) -> list[CheckMessage]:
+    from django.core.management import get_commands, load_command_class
+
+    commands = get_commands()
+
+    make_migrations = load_command_class(commands["makemigrations"], "makemigrations")
+    migrate = load_command_class(commands["migrate"], "migrate")
+
+    if not issubclass(
+        migrate.autodetector,  # type: ignore[missing-attribute]
+        PGViewsAutodetector,
+    ) or not issubclass(
+        make_migrations.autodetector,  # type: ignore[missing-attribute]
+        PGViewsAutodetector,
+    ):
+        return [
+            CheckWarning(
+                (
+                    "If you don't use PGViewsAutodetector on your migrate and makemigrations commands, "
+                    "django_pgviews will not detect and delete that views have been removed. "
+                    "You are seeing this because you or some other dependency has overwritten the commands "
+                    "from django_pgviews. "
+                ),
+                hint=(
+                    f"The makemigrations.Command.autodetector is {make_migrations.autodetector.__name__}, "  # type: ignore[missing-attribute]
+                    f"the migrate.Command.autodetector is {migrate.autodetector.__name__}."  # type: ignore[missing-attribute]
+                ),
+                id="django_pgviews.W001",
+            )
+        ]
+
+    return []