play framework unable to run an existing project

Question

I'm a rookie developer trying to run an application using play framework. I've followed the tutorial and can successfully create a new project.

However when I go to the directory that has the project I'm supposed to work on and enter the play command I get the following error:

[error] Not a valid command: play (similar: last, alias, loadp)
[error] Not a valid project ID: play
[error] Not a valid configuration: play
[error] Not a valid key: play (similar: clean)
[error] play

I have very little knowledge regarding the framework and don't know where to start correcting my mistake. Any suggestions ?

Answer 1

You have to run the play command this way:

./play cmd [app_path] [--options]

where in case of running a project, it is

./play run /path/to/projectname

Answer 2

I am facing this problem in the context of sub projects.

This is what worked for me.

---

Code:

import sbt._
import sbt.Keys._

object ApplicationBuild extends Build {

  val helloWorldProj = Project(id = "HelloWorld", base = file("helloworld"))    

  val appName = "WebApp"
  val appVersion = "1.0"
  val appDependencies = Seq()

  val webAppProj = PlayProject( appName, appVersion, appDependencies, path = file("webapp"), mainLang = PlayProject.SCALA)
    .dependsOn(helloWorldProj)
    .aggregate(helloWorldProj)

}

On running the play command, I get the following error:

Error:

[info] Set current project to HelloWorld (in build file:/D:/EclipseProjects/HelloWorldPlayMultiProject/)
[error] Not a valid command: play (similar: last, alias, loadp)
[error] Not a valid project ID: play
[error] Not a valid configuration: play
[error] Not a valid key: play (similar: play-hash, play-dist, play-conf)
[error] play
[error]     ^

Solution:

Now, if I rename helloWorldProj as zhelloWorldProj, it works! In this case, play sets the active project to WebApp.(Since webAppProj variable name alphabetically comes before zhelloWorldProj)

I can then change the active project to HelloWorld by giving the command project HelloWorld.

I think this has something to do with how sbt finds the Project objects using reflection.