A Django database router that defaults everything to `default` database, but allows to change it via a context manager (or decorator)

overridable_db_router.py

import threading
from contextlib import contextmanager


class DBConfig(threading.local):
    database_name: str = "default"


DB_CONFIG = DBConfig()


class OverridableDatabaseRouter:
    def db_for_read(self, model, **hints):
        return DB_CONFIG.database_name

    def db_for_write(self, model, **hints):
        return DB_CONFIG.database_name

    def allow_migrate(self, db, app_label, model_name=None, **hints):
        return db == "default"

    def allow_syncdb(self, db, model):
        return db == "default"

    def allow_relation(self, obj1, obj2, **hints):
        return None


@contextmanager
def force_database(database_name: str):
    """A context manager/decorator to temporarily set and revert the database name"""
    old_database_name = DB_CONFIG.database_name
    DB_CONFIG.database_name = database_name
    yield
    DB_CONFIG.database_name = old_database_name