如何在Play Guice模块中访问请求? [英] How can I access request in Play Guice Module?

问题描述

我正在编写一个处理多个系统的应用程序.用户可以选择要使用的系统，然后我将该系统ID存储在会话(客户端会话)中

I am writing an application which handles multiple systems. The user can choose the system which he wants to work with and I store that system ID in session (client session)

现在我有Service类，可以说CustomerService.

Now I have Service classes, lets say CustomerService.

class CustomerService(val systemID: String) {
    // Implementation
}

我想使用Guice将Customer实例注入到Controller中.但是我想用存储在会话中的SystemID实例化CustomerService.

I want to use Guice to inject the Customer instance to the Controllers. But I want to instantiate the CustomerService with SystemID which is stored in the session.

如何在Guice模块中访问request.session?

How can I access request.session in Guice Module?

在上面简化了我的代码.我的实际代码使用接口.我该如何使用辅助注射?

Had simplified my code above. My actual code uses interfaces. How can I use assisted inject for this?

trait CustomerService(val systemID: String) {
    // Definition
}

object CustomerService{

  trait Factory {
    def apply(systemID: String) : CustomerService
  }

}

class DefaultCustomerService @Inject() (@Assisted systemID: String)
  extends CustomerService {
    // Definition
}

class CustomerController @Inject()(
                            val messagesApi: MessagesApi,
                            csFactory: CustomerService.Factory)
{
}

这给了我: CustomerService是一个接口，而不是具体的类.无法创建AssistedInject工厂.

This gives me: CustomerService is an interface, not a concrete class. Unable to create AssistedInject factory.

而且我不想将Factory放在DefaultCustomerService下并在控制器中使用DefaultCustomerService.Factory.这是因为对于单元测试，我将使用TestCustomerService存根，并且希望依赖注入将TestCustomerService而不是DefaultCustomerService注入到控制器中.

And I do not want to put the Factory under DefaultCustomerService and use DefaultCustomerService.Factory in the controller. This is because for unit testing I will be using TestCustomerService stub and want Dependency Injection to inject TestCustomerService into the controller instead of DefaultCustomerService.

推荐答案

您不应这样做.如果您需要注入需要运行时值的实例，则可以使用guice的 AssistedInject .

You should not do that. If you need to inject an instance of something that requires runtime-values, you can use guice's AssistedInject.

在游戏中如何使用它:

1.使用运行时值作为参数创建服务的工厂:

1. Create a factory of your service with the runtime value as parameter:

object CustomerService {
  trait Factory {
    def apply(val systemID: String): CustomerService
  }
}

2.使用辅助参数实施服务

2. Implement your service with the assisted parameter

class CustomerService @Inject() (@Assisted systemId: String) { .. }

3.将工厂绑定到您的guice模块中:

3. Bind the factory in your guice module:

install(new FactoryModuleBuilder()
  .implement(classOf[CustomerService], classOf[CustomerServiceImpl])
  .build(classOf[CustomerService.Factory]))

4.最后将工厂注入您需要客户服务的地方:

4. And finally inject the factory where you need the customer service:

class MyController @Inject() (csFactory: CustomerService.Factory) { .. }

这是辅助注射的另一个示例: https://www.playframework.com/documentation/2.5.x/ScalaTestingWebServiceClients

Here's another example of assisted inject: https://www.playframework.com/documentation/2.5.x/ScalaTestingWebServiceClients

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