如何在python-dependency-injector外层容器中链接循环依赖的子容器？

在领域模块使用子容器组织时，常会遇到UserContainer与PaymentContainer这类循环依赖的情况，可通过依赖注入容器的延迟解析特性来处理，具体实现如下：

修改后的完整代码 #

from dataclasses import dataclass
import dependency_injector.containers as containers
import dependency_injector.providers as providers

@dataclass
class UserService:
    payments: "PaymentsService"

    def user_action(self):
        print("user action")
        self.payments.payment_action()


@dataclass
class PaymentsService:
    users: UserService

    def payment_action(self):
        print("payment action")


class UserContainer(containers.DeclarativeContainer):
    payments = providers.DependenciesContainer()

    service = providers.Factory(UserService, payments=payments.service)


class PaymentContainer(containers.DeclarativeContainer):
    users = providers.DependenciesContainer()

    service = providers.Factory(PaymentsService, users=users.service)


class ApplicationContainer(containers.DeclarativeContainer):
    # 利用lambda延迟引用自身容器，解决循环绑定
    users = providers.Container(UserContainer, payments=lambda self: self.payments)
    payments = providers.Container(PaymentContainer, users=users)

核心说明 #

• 使用lambda self: self.payments作为UserContainer的payments参数，借助容器的延迟解析机制，当UserContainer需要依赖时，会从ApplicationContainer中获取已初始化的payments容器。
• 这种方式既完成了两个子容器的循环绑定，又能保证服务实例在实际调用时正确获取到依赖对象。

验证运行 #

可以添加以下代码验证功能正常：

if __name__ == "__main__":
    app_container = ApplicationContainer()
    user_service = app_container.users.service()
    payment_service = app_container.payments.service()

    user_service.user_action()
    payment_service.payment_action()

内容的提问来源于stack exchange，提问作者Arseniy