DBRouter class for django

dbrouter.py

class DBRouter(object):
    """
    A router to control all database operations on models in the auth application.
    """
    def db_for_read(self, model, **hints):
        """
        Attempts to read auth models go to auth_db.
        """
        if model._meta.app_label in settings.DATABASES.keys():
            return model._meta.app_label
        return 'default'

    def db_for_write(self, model, **hints):
        """
        Attempts to write auth models go to auth_db.
        """
        if model._meta.app_label in settings.DATABASES.keys():
            return model._meta.app_label
        return 'default'

    def allow_relation(self, obj1, obj2, **hints):
        """
        Allow relations if a model in the auth app is involved.
        """
        if obj1._meta.app_label in settings.DATABASES.keys():
            db_obj1 = obj1._meta.app_label
        else:
            db_obj1 = 'default'
        if obj2._meta.app_label in settings.DATABASES.keys():
            db_obj2 = obj2._meta.app_label
        else:
            db_obj2 = 'default'
        if db_obj1 == db_obj2:
            return True
        return False

    def allow_migrate(self, db, app_label, model_name=None, **hints):
        """
        Make sure the auth app only appears in the 'auth_db' database.
        """
        app_db = "default"
        if app_label in settings.DATABASES.keys():
            app_db = app_label
        return app_db == db