在django 1.11中，如何允许用户登录只读数据库？

class ReadOnlyDBRouter:
    def db_for_read(self, model, **hints):
        # 返回只读数据库的别名
        return 'readonly_db'

    def db_for_write(self, model, **hints):
        # 返回默认数据库的别名
        return None

    def allow_relation(self, obj1, obj2, **hints):
        # 允许任意两个对象之间的关联
        return True

    def allow_migrate(self, db, app_label, model_name=None, **hints):
        # 允许在只读数据库上执行迁移操作
        if db == 'readonly_db':
            return True
        return None

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'readwrite_db',
        'USER': 'your_username',
        'PASSWORD': 'your_password',
        'HOST': 'localhost',
        'PORT': '3306',
    },
    'readonly_db': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'readonly_db',
        'USER': 'your_username',
        'PASSWORD': 'your_password',
        'HOST': 'localhost',
        'PORT': '3306',
    }
}

DATABASE_ROUTERS = ['your_project_name.routers.ReadOnlyDBRouter']