def load_items(connection: BaseDatabaseWrapper, **kwargs) -> None:
"""
This function provides a way to load items into memory
on server startup from the target database.
It unregisters itself to ensure that it is only run
once per startup.
:param connection: a Django BaseDatabaseWrapper object
:param kwargs: additional keyword arguments
:return: None
"""
connection = connections[DEFAULT_DB_ALIAS]
connection.prepare_database()
executor = MigrationExecutor(connection)
targets = executor.loader.graph.leaf_nodes()
autodetector = MigrationAutodetector(
executor.loader.project_state(),
ProjectState.from_apps(apps),
)
unmade_migrations = autodetector.changes(graph=executor.loader.graph)
unrun_migrations = executor.migration_plan(targets)
all_migrations_run = True
# If there are any unmade migrations, we can't safely load the items into memory
for app in unmade_migrations:
if APP_NAME in str(app):
print("Can't load items. Detected unmade migrations.")
all_migrations_run = False
break
# If there aren't unmade migrations, check if any migrations still need applied
if all_migrations_run:
for migration, _ in unrun_migrations:
if APP_NAME in str(migration):
print("Can't load items. Migrations need applied.")
all_migrations_run = False
break
# If all migrations are run and there aren't unmade migrations, we load the items into memory
if all_migrations_run:
for item in Item.objects.all():
items[item.id] = item
# We do this to ensure this runs ONLY once per startup
connection_created.disconnect(load_items)
