Scala + Play框架+ Slick + Akka-Akka Actor的数据库访问 [英] Scala + Play Framework + Slick + Akka - DB Access from Akka Actor
问题描述
在接收TCP特定消息时,我需要查询我的数据库.为此,我创建了一个称为DBActor的Actor,并将其加载到Application.scala
文件
At the receival of a TCP specific message, i need to query my DB. For that, i created an Actor that is called DBActor and it's loaded in Application.scala
file
class Application @Inject() (system: ActorSystem) extends Controller {
val tcpServer = system.actorOf(Props[TCPServer], "tcpserver")
val dbActor = system.actorOf(Props[DBActor], "dbActor")
}
Tcp服务器是收到消息的参与者,需要将该消息推送到DB Actor上
Tcp server is the actor that received the message and need to push it on DB Actor with that
val handler = context.actorSelection("/dbActor")
根据Play框架规范,DB actor以此方式进行了初始化
DB actor is so initialized in this way, according to Play Framework specifications
object DBActor {
def props() =
Props(classOf[DBActor])
}
class DBActor @Inject() (protected val dbConfigProvider:
DatabaseConfigProvider) extends Actor
with HasDatabaseConfigProvider[JdbcProfile]
with ActorLogging
with TableComponent {
import akka.io.Tcp._
import driver.api._
val table = TableQuery[Table]
def receive: Receive = {
case GetConfig(id) => {
sender ! Await.result(db.run(table.filter(_.id=== id).result.headOption),
Duration.Inf)
.map { x => x.config }
}
}
}
目前,由于错误,actor尚未构建
At the moment, actor is not constructed due to the error
Error injecting constructor, java.lang.IllegalArgumentException:
no matching constructor found on class tcp.DBActor for arguments []
at controllers.Application.<init>(Application.scala:17)
at controllers.Application.class(Application.scala:17)
因此,我需要一种将DB配置注入DBactor中以查询数据库或替代方法的方法.在此之前,我评估过注入DAO或将所需的DAO转换为actor都失败了.
So i need a way to inject the db configuration in the DBactor for querying the database or an alternative. I evaluated before that to inject a DAO or transforming the DAO I needed into an actor, both failed.
在这一点上的问题是,赋予演员访问数据库或至少访问控制器是否有意义?如果无法完成,还有哪些选择?
Question at this point is, does it make any sense giving an actor the access to the db or, at least, a controller? If can't be done, what are the alternatives?
推荐答案
您需要的是注入的actor.完整说明可在播放文档中找到( https: //www.playframework.com/documentation/2.5.x/ScalaAkka#Dependency-injecting-actors ),但这是要点:
What you need is an injected actor. The full description can be found here in the play documentation (https://www.playframework.com/documentation/2.5.x/ScalaAkka#Dependency-injecting-actors), but here's the gist of it:
您可以像这样定义actor绑定:
You define the actor binding like so:
bindActor[DBActor]("db-actor")
然后将actor注入到控制器中,如下所示:
And inject the actor in the controller like so:
class Application @Inject() (@Named("db-actor") dbActor: ActorRef) extends Controller {
换句话说,您应尽可能避免使用Await.result
.在您的情况下,可以很容易地将其替换为:
On a different note, you should avoid Await.result
whenever possible. In your scenario, this could probably easily be replaced with:
val senderRef = sender()
db.run(table.filter(_.id=== id).result.headOption)
.map(res => senderRef ! res.config)
请注意,发件人ref之前已存储,因为它在map
内部不再有效(请参见sender()
方法的scaladoc).
Note that the sender ref is stored before, because it is no longer valid inside the map
(see scaladoc of the sender()
method).
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