Dependency injection for bounded generic types

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Noor Rayni

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Aug 5, 2019, 3:52:02 AM8/5/19
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I would appreciate if I could get some help with the following. I am trying to do dependency injection for traits that have bounded parameter type. I am consistently having 

No implementation for dao.ImageDAO<models.ProductImageSet> was bound. while locating dao.ImageDAO<models.ProductImageSet>



trait ImageDAO[T <: ImageSet] {

 
def find(id: String): ImageDisplay[T]

 
def find(req: ImageSearch): ImageResponse[T]
}

class ProductImageDAO @Inject() (environment: Environment) extends ImageDAO[ProductImageSet] {
...
}

class ProfileImageDAO @Inject() (environment: Environment) extends ImageDAO[ProfileImageSet] {
...
}

case class ProductImageSet(swatchImage: BaseImage, smallImage: BaseImage, mediumImage: BaseImage, largeImage: BaseImage) extends ImageSet

case class ProfileImageSet(smallImage: BaseImage, mediumImage: BaseImage) extends ImageSet

And now, the service trait and its implementation

trait ImageService[A <: ImageSet] {
 
def retrieve(id: String): ImageDisplay[A]

 
def retrieve(req: ImageSearch): ImageResponse[A]
}

class ImageServiceImpl[T <: ImageSet] @Inject() (imageDAO: ImageDAO[T]) extends ImageService[T] {

 
def retrieve(id: String): ImageDisplay[T] = imageDAO.find(id)

 
def retrieve(req: ImageSearch): ImageResponse[T] = ???
}

Here is my class Module.scala where I want the dependency injection to happen.

class MyModule extends AbstractModule {
  protected override def configure() {
    bind(new TypeLiteral[ImageDAO[ProductImageSet]](){}).to(classOf[ProductImageDAO]).asEagerSingleton()
    bind(new TypeLiteral[ImageService[ProfileImageSet]](){}).to(classOf[ImageServiceImpl[ProfileImageSet]]).asEagerSingleton()
    bind(new TypeLiteral[ImageService[ProductImageSet]](){}).to(classOf[ImageServiceImpl[ProductImageSet]]).asEagerSingleton()
   }

}
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