Compile Error in 1.4 Tech Hub Starter (Scala)

Resolution : do not use “lagom” as the project name when starting a project from Tech Hub

Lagom : Version 1.4

API : Scala

Operating System : MacOS 10.13.3

JDK : Oracle 1.8.0_152

java version “1.8.0_152” Java™ SE Runtime Environment (build 1.8.0_152-b16) Java HotSpot™ 64-Bit Server VM (build 25.152-b16, mixed mode)

Library Dependencies

standard dependencies for the tech hub starter project

Expected Behavior

1. download lagom scala 1.4 starter project
2. run permissions adjustments on sbt files per the instructions
3. run ‘sbt runAll’, project initializes
4. lagom started compiles and runs,
5. open browser to http://localhost:9000/api/hello/World and see message

Actual Behavior

1. as expected
2. as expected
3. as expected
4. lagom starts up the demo services, but sbt fails to compile the following
   • lagom/lagom-impl/src/main/scala/com/example/hello/impl/LagomLoader.scala:26
   • lagom/lagom-impl/src/main/scala/com/example/hello/impl/LagomLoader.scala:27
   • lagom/lagom-impl/src/main/scala/com/example/hello/impl/LagomLoader.scala:33
   • lagom/lagom-impl/src/main/scala/com/example/hello/impl/LagomLoader.scala:39
   • (see below for complete sbt output)
5. receive the browser error “Action Not Found For request ‘GET /api/hello/World’ These routes have been tried, in this order: GET \Q/stream\E Service: lagom-stream (http://0.0.0.0:57104)”

sbt output

2012MBP:lagom sailer$ sbt runAll
[info] Loading project definition from /Users/sailer/Downloads/lagom/project
[info] Set current project to lagom (in build file:/Users/sailer/Downloads/lagom/)
[info] Starting Kafka
[info] Starting Cassandra
..........
[info] Cassandra server running at 127.0.0.1:4000
2018-01-29T11:51:49.112Z [info] akka.event.slf4j.Slf4jLogger [] - Slf4jLogger started
2018-01-29T11:51:51.470Z [info] com.lightbend.lagom.discovery.ServiceLocatorServer [] - Service locator can be reached at http://localhost:9008
2018-01-29T11:51:51.470Z [info] com.lightbend.lagom.discovery.ServiceLocatorServer [] - Service gateway can be reached at http://localhost:9000
[info] Service locator is running at http://localhost:9008
[info] Service gateway is running at http://localhost:9000
04:51:53.779 [info] play.core.server.AkkaHttpServer [] - Listening for HTTP on /0:0:0:0:0:0:0:0:57104
04:51:53.946 [info] play.core.server.AkkaHttpServer [] - Listening for HTTP on /0:0:0:0:0:0:0:0:63779
[info] Compiling 3 Scala sources to /Users/sailer/Downloads/lagom/lagom-impl/target/scala-2.12/classes...
04:51:54.819 [info] akka.event.slf4j.Slf4jLogger [] - Slf4jLogger started
04:51:56.073 [info] play.api.Play [] - Application started (Dev)
[error] /Users/sailer/Downloads/lagom/lagom-impl/src/main/scala/com/example/hello/impl/LagomLoader.scala:26: illegal cyclic reference involving class LagomApplication
[error] abstract class LagomApplication(context: LagomApplicationContext)
[error]                                ^
[error] /Users/sailer/Downloads/lagom/lagom-impl/src/main/scala/com/example/hello/impl/LagomLoader.scala:27: no arguments allowed for nullary constructor Object: ()Object
[error]   extends LagomApplication(context)
[error]                            ^
[error] /Users/sailer/Downloads/lagom/lagom-impl/src/main/scala/com/example/hello/impl/LagomLoader.scala:33: not found: value serverFor
[error]   override lazy val lagomServer = serverFor[LagomService](wire[LagomServiceImpl])
[error]                                   ^
[error] /Users/sailer/Downloads/lagom/lagom-impl/src/main/scala/com/example/hello/impl/LagomLoader.scala:33: recursive lazy value lagomServer needs type
[error]   override lazy val lagomServer = serverFor[LagomService](wire[LagomServiceImpl])
[error]                                                               ^
[error] /Users/sailer/Downloads/lagom/lagom-impl/src/main/scala/com/example/hello/impl/LagomLoader.scala:39: not found: value persistentEntityRegistry
[error]   persistentEntityRegistry.register(wire[LagomEntity])
[error]   ^
[error] 5 errors found
[error] (lagom-impl/compile:compileIncremental) Compilation failed
[info] Service lagom-stream-impl listening for HTTP on 0:0:0:0:0:0:0:0:57104
[info] Service lagom-impl listening for HTTP on 0:0:0:0:0:0:0:0:63779
[info] (Services started, press enter to stop and go back to the console...)

Reproducible Test Case

Using the standard starter from Tech Hub reproduces this failure.

[TimMoore]

I think there’s a way to add some validation to this field, so we should disallow values that are known to be broken like this.

[jfspencer]

@renatocaval ah yes, thanks! I was using “lagom” as the project name from the tech hub page. should have figured it would have caused name collisions 😃