Question

我试图使用play和scala创建一个简单的restful api。我已经能够创建一些基本路由，让它发回json响应，并验证在POST中发送的json。现在我想在postgres数据库中添加持久性，这是它开始崩溃的地方。

我首先将db信息添加到我的application.conf中，创建了一个演变来创建一个表。然后我尝试点击我的GET端点以查看它是否运行了演变，但我反而得到了一个错误。这是html的错误输出（我使用我的浏览器命中端点）：

CreationException: Unable to create injector, see the following errors:

1) A binding to play.api.db.DBApi was already configured at play.api.db.DBModule.bindings(DBModule.scala:25):
Binding(interface play.api.db.DBApi to ProviderConstructionTarget(class play.api.db.DBApiProvider)) (via modules: com.google.inject.util.Modules$OverrideModule -> play.api.inject.guice.GuiceableModuleConversions$$anon$1).
  at play.api.db.slick.evolutions.EvolutionsModule.bindings(EvolutionsModule.scala:15):
Binding(interface play.api.db.DBApi to ConstructionTarget(class play.api.db.slick.evolutions.internal.DBApiAdapter) in interface javax.inject.Singleton) (via modules: com.google.inject.util.Modules$OverrideModule -> play.api.inject.guice.GuiceableModuleConversions$$anon$1)

com.google.inject.CreationException: Unable to create injector, see the following errors:

com.google.inject.internal.Errors.throwCreationExceptionIfErrorsExist(Errors.java:466)
     com.google.inject.internal.InternalInjectorCreator.initializeStatically(InternalInjectorCreator.java:155)
     com.google.inject.internal.InternalInjectorCreator.build(InternalInjectorCreator.java:107)
     com.google.inject.Guice.createInjector(Guice.java:96)
     com.google.inject.Guice.createInjector(Guice.java:84)
play.api.inject.guice.GuiceBuilder.injector(GuiceInjectorBuilder.scala:181)
     play.api.inject.guice.GuiceApplicationBuilder.build(GuiceApplicationBuilder.scala:123)
     play.api.inject.guice.GuiceApplicationLoader.load(GuiceApplicationLoader.scala:21)
     play.core.server.DevServerStart$$anonfun$mainDev$1$$anon$1$$anonfun$get$1$$anonfun$apply$1$$anonfun$1$$anonfun$2.apply(DevServerStart.scala:168)
     play.core.server.DevServerStart$$anonfun$mainDev$1$$anon$1$$anonfun$get$1$$anonfun$apply$1$$anonfun$1$$anonfun$2.apply(DevServerStart.scala:164)
     play.utils.Threads$.withContextClassLoader(Threads.scala:21)
     play.core.server.DevServerStart$$anonfun$mainDev$1$$anon$1$$anonfun$get$1$$anonfun$apply$1$$anonfun$1.apply(DevServerStart.scala:164)
     play.core.server.DevServerStart$$anonfun$mainDev$1$$anon$1$$anonfun$get$1$$anonfun$apply$1$$anonfun$1.apply(DevServerStart.scala:131)
     scala.Option.map(Option.scala:146)
     play.core.server.DevServerStart$$anonfun$mainDev$1$$anon$1$$anonfun$get$1$$anonfun$apply$1.apply(DevServerStart.scala:131)
     play.core.server.DevServerStart$$anonfun$mainDev$1$$anon$1$$anonfun$get$1$$anonfun$apply$1.apply(DevServerStart.scala:129)
     scala.util.Success.flatMap(Try.scala:231)
     play.core.server.DevServerStart$$anonfun$mainDev$1$$anon$1$$anonfun$get$1.apply(DevServerStart.scala:129)
     play.core.server.DevServerStart$$anonfun$mainDev$1$$anon$1$$anonfun$get$1.apply(DevServerStart.scala:121)
     scala.concurrent.impl.Future$PromiseCompletingRunnable.liftedTree1$1(Future.scala:24)
     scala.concurrent.impl.Future$PromiseCompletingRunnable.run(Future.scala:24)
     java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1423)
     java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
     java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:902)
     java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1689)
     java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1644)
     java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

这是我的路线（请注意我实际上并没有尝试连接到数据库）：

GET     /cities                     controllers.CityController.index

连接到此控制器方法：

def index = Action {
    Ok(Json.obj("status" ->"OK", "message" -> "You did the thing!"))
  }

这是我的application.conf，为简洁起见删除了注释：

akka {
}

play.crypto.secret = "changeme"

play.modules {
}

play.i18n {
  langs = [ "en" ]
}

play.http {
  session {
  }

  flash {
  }
}

play.server.netty {
}

play.ws {
  ssl {
  }
}

play.cache {
}

play.filters {
  cors {
  }

  csrf {
  }

  headers {
  }

  hosts {
  }
}

play.evolutions {
}

play.db {
  prototype {
  }
}

db {
  db.default.driver=org.postgresql.Driver
  db.default.jdbcUrl="jdbc:postgresql://localhost:5432/transit_service"
  db.default.username="redacted"
  db.default.password="redacted"
  db.default.logSql=true
}

我的演变是一个相当简单的创建表语句，它位于conf / evolutions / default / 1.sql下。

我很感激能够理解为什么会出现这种错误，以及如何让这种错误得以实现。

Answer 1

Matthias Eckhart在评论中指出：从build.sbt中的libraryDependencies中删除jdbc条目是解决问题的方法。

播放错误：无法创建进样器

1 个答案: