Akka Play guice bindings tagless final (TF) 支持

如何解决Akka Play guice bindings tagless final (TF) 支持

我有这个绑定来在我的应用程序中配置 Logger[IO]（带有这一行的模块在 guice.conf 文件中）：

class CatsEffectModule extends AbstractModule with ScalaModule {

  override def configure(): Unit = {
    bind[Logger[IO]].toInstance(Slf4jLogger.getLogger[IO])
  }

}

然后在应用程序中我可以这样做：

@Singleton
class MyClass @Inject()(implicit logger: Logger[IO]) { ... }

这在应用程序中运行良好。

但是在 GuiceInjectorBuilder 中使用时不起作用（用于测试）：

import play.api.inject.guice.GuiceInjectorBuilder


private val application: Injector = new GuiceInjectorBuilder()
    .bindings(bind[ExecutionContext].to(ExecutionContext.global))
    .bindings(bind[ApplicationLifecycle].to[DefaultApplicationLifecycle])
    .bindings(new CatsEffectModule())
    .build()

application.instanceOf[MyClass]

它给了我一个错误：

No implementation for io.chrisdavenport.log4cats.Logger was bound.
[info]   Did you mean?
[info]     io.chrisdavenport.log4cats.Logger<cats.effect.IO> bound  at guice.CatsEffectModule.configure(CatsEffectModule.scala:21) (via modules: com.google.inject.util.Modules$OverrideModule -> guice.CatsEffectModule)

测试中的每个 TF 实体注入都像这样失败。 Akka Play 运行 Guice 的方式和 GuiceInjectorBuilder 的工作方式之间有什么区别吗？

代码示例：https://github.com/DenisNovac/play-tf-test

解决方法

codingwell (https://github.com/codingwell/scala-guice) 的 Scala-guice 允许绑定 TF 类（它是为 vanilla Guice 而不是 Play Guice 制作的）。它们将正确绑定到依赖类，但 GuiceInjectorBuilder 不会让您通过 instanceOf 方法获取它。

但如果你同时使用两个绑定，它似乎在两个方向都有效：

import cats.effect.IO
import com.google.inject.AbstractModule
import net.codingwell.scalaguice.ScalaModule
import org.scalatest.flatspec.AnyFlatSpec
import org.scalatest.matchers.should.Matchers
import play.api.inject.guice.GuiceInjectorBuilder
import play.api.inject.{ApplicationLifecycle,DefaultApplicationLifecycle,Injector,bind}

import scala.concurrent.ExecutionContext

class WorkingModule extends AbstractModule with ScalaModule {

  override def configure(): Unit =
    bind[CustomTFInterface[IO]].toInstance(new CustomTFInterfaceImpl)
}

class HomeControllerSpec extends AnyFlatSpec with Matchers {

  it should "test1" in {
    val application: Injector = new GuiceInjectorBuilder()
      .bindings(bind[ExecutionContext].to(ExecutionContext.global))
      .bindings(bind[ApplicationLifecycle].to[DefaultApplicationLifecycle])
      .bindings(bind[CustomTFInterface[IO]].toInstance(new CustomTFInterfaceImpl))
      .bindings(new CatsEffectModule())
      .injector()

    application.instanceOf[CustomTFInterface[IO]] // works
    //application.instanceOf[InjecableWithTfDependencies] // fails

  }

  it should "test2" in {
    val application: Injector = new GuiceInjectorBuilder()
      .bindings(bind[ExecutionContext].to(ExecutionContext.global))
      .bindings(bind[ApplicationLifecycle].to[DefaultApplicationLifecycle])
      .bindings(new WorkingModule())
      .bindings(new CatsEffectModule())
      .injector()

    //application.instanceOf[CustomTFInterface[IO]] // fails
    application.instanceOf[InjecableWithTfDependencies] // works
  }

  it should "test3" in {
    val application: Injector = new GuiceInjectorBuilder()
      .bindings(bind[ExecutionContext].to(ExecutionContext.global))
      .bindings(bind[ApplicationLifecycle].to[DefaultApplicationLifecycle])
      // both binds together also works
      .bindings(new WorkingModule())
      .bindings(bind[CustomTFInterface[IO]].toInstance(new CustomTFInterfaceImpl))
      .bindings(new CatsEffectModule())
      .injector()

    application.instanceOf[CustomTFInterface[IO]]       // works
    application.instanceOf[InjecableWithTfDependencies] // works
  }

}

也许有一种方法可以让 scala-guice 和 play 一起工作，但我没有成功。

完整示例：https://github.com/DenisNovac/play-tf-test