from django.conf import settingsDATABASE_MAPPING = settings.DATABASE_APPS_MAPPINGclass DatabaseAppsRouter(object):"""A router to control all database operations on models for differentdatabases.In case an app is not set in settings.DATABASE_APPS_MAPPING, the routerwill fallback to the `default` database.Settings example:DATABASE_APPS_MAPPING = {'app1': 'db1', 'app2': 'db2'}"""def db_for_read(self, model, **hints):""""Point all read operations to the specific database."""if model._meta.app_label in DATABASE_MAPPING:return DATABASE_MAPPING[model._meta.app_label]return Nonedef db_for_write(self, model, **hints):"""Point all write operations to the specific database."""if model._meta.app_label in DATABASE_MAPPING:return DATABASE_MAPPING[model._meta.app_label]return Nonedef allow_relation(self, obj1, obj2, **hints):"""Allow any relation between apps that use the same database."""db_obj1 = DATABASE_MAPPING.get(obj1._meta.app_label)db_obj2 = DATABASE_MAPPING.get(obj2._meta.app_label)if db_obj1 and db_obj2:if db_obj1 == db_obj2:return Trueelse:return Falsereturn Nonedef allow_syncdb(self, db, model):"""Make sure that apps only appear in the related database."""if db in DATABASE_MAPPING.values():return DATABASE_MAPPING.get(model._meta.app_label) == dbelif model._meta.app_label in DATABASE_MAPPING:return Falsereturn Nonedef allow_migrate(self, db, app_label, model=None, **hints):"""Make sure the auth app only appears in the 'auth_db'database."""if db in DATABASE_MAPPING.values():return DATABASE_MAPPING.get(app_label) == dbelif app_label in DATABASE_MAPPING:return Falsereturn None