SBT因不正确的追加错误而失败.我使用我已经看过很多次的构建文件的确切格式.
build.sbt:
lazy val backend = (project in file("backend")).settings(
name := "backend",
libraryDependencies ++= (Dependencies.backend)
).dependsOn(api).aggregate(api)
dependencies.scala:
import sbt._
object Dependencies {
lazy val backend = common ++ metrics
val common = Seq(
"com.typesafe.akka" %% "akka-actor" % Version.akka,
"com.typesafe.akka" %% "akka-cluster" % Version.akka,
"org.scalanlp.breeze" %% "breeze" % Version.breeze,
"com.typesafe.akka" %% "akka-contrib" % Version.akka,
"org.scalanlp.breeze-natives" % Version.breeze,
"com.google.guava" % "guava" % "17.0"
)
val metrics = Seq("org.fusesource" % "sigar" % "1.6.4")
我不是为什么SBT抱怨的原因
error: No implicit for Append.Values[Seq[sbt.ModuleID], Seq[Object]] found,
so Seq[Object] …在Slick中执行过滤器连接时,以下两种方法之间的区别是什么？
val query = for {
c <- coffees if c.price < 9.0
s <- c.supplier -- assuming there is a foreign key
} yield (c.name, s.name)
和
val query = for {
(cof, sup) <- coffees.filter(_.price < 9.0) join supplier on(_.supId === _.id)
} yield (cof.name, sup.name)
在akka流阶段FlowShape[A, B],我需要在A上进行的部分处理是使用使用A数据构建的查询来保存/查询数据存储.但是那个数据存储驱动程序查询给了我一个未来,我不知道如何最好地处理它(我的主要问题在这里).
case class Obj(a: String, b: Int, c: String)
case class Foo(myobject: Obj, name: String)
case class Bar(st: String)
//
class SaveAndGetId extends GraphStage[FlowShape[Foo, Bar]] {
val dao = new DbDao // some dao with an async driver
override def createLogic(inheritedAttributes: Attributes) = new GraphStageLogic(shape) {
setHandlers(in, out, new InHandler with Outhandler {
override def onPush() = {
val foo = grab(in)
val add = foo.record.value()
val result: Future[String] = dao.saveAndGetRecord(add.myobject)//saves and returns id as string
//the …我使用graph dsl根据我看到的一些示例代码创建了一些流处理作业.一切都运行得很好,我只是很难理解符号:(更新为2.4)
def elements: Source[Foos] = ...
def logEveryNSink = // a sink that logs
def cleaner: Flow[Foos, Bars, Unit] = ...
def boolChecker(bar: Bar)(implicit ex: ExecutionContext): Future[Boolean] = ...
val mySink = Sink.foreach[Boolean](println(_))
val lastly = Flow[Bars].mapAsync(2)(x => boolChecker(x).toMat(mySink)(Keep.right)
val materialized = RunnableGraph.fromGraph(
GraphDSL.create(lastly) { implicit builder =>
baz => {
import GraphDSL.Implicits._
val broadcast1 = builder.add(Broadcast[Foos](2))
val broadcast2 = builder.add(Broadcast[Bars](2))
elements ~> broadcast1 ~> logEveryNSink(1)
broadcast1 ~> cleaner ~> broadcast2 ~> baz
~> broadcast2 ~> logEveryNSink(1)
ClosedShape
} …