编译时依赖项注入项目中的EvolutionsComponents

Question

我试图了解如何使用编译时DI运行演化。

import play.api.ApplicationLoader.Context
import play.api.cache.EhCacheComponents
import play.api.mvc.EssentialFilter
import play.api.routing.Router
import play.api._
import play.api.db.evolutions.{ DynamicEvolutions, EvolutionsComponents}
import play.filters.gzip.GzipFilter
import router.Routes

class AppLoader extends ApplicationLoader  {
  override def load(context: Context): Application = {
    LoggerConfigurator(context.environment.classLoader).foreach(_.configure(context.environment))
    new AppComponents(context).application
  }


}

class AppComponents(context: Context) extends BuiltInComponentsFromContext(context) with EhCacheComponents with EvolutionsComponents {

  lazy val applicationController = new controllers.Application(defaultCacheApi)
  lazy val usersController = new controllers.Users(defaultCacheApi)
  lazy val assets = new controllers.Assets(httpErrorHandler)

  applicationEvolutions

  // Routes is a generated class
  override def router: Router = new Routes(httpErrorHandler, applicationController, usersController, assets)

  val gzipFilter = new GzipFilter(shouldGzip =
    (request, response) => {
      val contentType = response.header.headers.get("Content-Type")
      contentType.exists(_.startsWith("text/html")) || request.path.endsWith("jsroutes.js")
    })

  override lazy val httpFilters: Seq[EssentialFilter] = Seq(gzipFilter)


}

但是我一直收到错误错误：（19，7）类AppComponents必须是抽象的，因为未定义类型=> play.api.db.DBApi的特征EvolutionsComponents中的方法dbApi类AppComponents（context：Context）扩展了BuiltInComponentsFromContext（context ）与EhCacheComponents和EvolutionsComponents

我是Scala的新手。

Answer 1

dbApi来自DBComponents特性，因此您的AppComponents类还需要扩展DBComponents 。 您还需要为连接池扩展HikariCPComponents 。

class AppComponents(context: Context) extends BuiltInComponentsFromContext(context)
  with EhCacheComponents
  with EvolutionsComponents
  with DBComponents
  with HikariCPComponents {

确保将evolutions和jdbc依赖项添加到build.sbt文件中。

Answer 2

我需要扩展所有这些内容。 更多阅读Cake Pattern 播放文档

class AppComponents(context: Context) extends BuiltInComponentsFromContext(context) with EhCacheComponents with EvolutionsComponents with DBComponents with HikariCPComponents{

并在build.sbt中添加jdbc suport

libraryDependencies ++= Seq(
 filters,
 evolutions,
 jdbc,
 cache,

....