How to define arbitrary tasks in the Play Framewor

问题:

How to define arbitrary tasks in the Play Framework?

I mean tasks run from the command line, something similar to ruby rake.

I'm aware of the ant tool but looking for a better alternative.

回答1:

[edit] This answer is for the Play 1.* series!

You should write a custom module, then your commands go into the commands.py file, ref: http://www.playframework.org/documentation/1.2.4/releasenotes-1.1#commands

You can look at existing modules to get inspired, eg: https://github.com/sim51/logisima-play-yml/blob/master/commands.py

Basically you define the commands you want and launch them from the "execute" method, eg:

COMMANDS = ['namespace:command']

def execute(**kargs):
    command = kargs.get("command")
    app = kargs.get("app")
    args = kargs.get("args")
    env = kargs.get("env")

    if command == "namespace:command":
        do_something()

if you want to launch something java - often the case! -:

def do_something():
    java_cmd = app.java_cmd([], None, "play.modules.mymodule.MyClass", args)
        try:
            subprocess.call(java_cmd, env=os.environ)
        except OSError:
            print "Could not execute the java executable, please make sure the JAVA_HOME environment variable is set properly (the java executable should reside at JAVA_HOME/bin/java). "
            sys.exit(-1)
        print

Ps.

creating a custom module is as easy as:

play new-module mymodule

This is a primer: http://playframework.wordpress.com/2011/02/27/play-modules/ , considering that official Play! module documentation is quite limited in that respect

edit

I thought I'd add a little piece of information:

before being able to execute your commands, you must BUILD your module. It does not run like the rest of play with a dynamic compilation.

play build-module mymodule

new-module/build-module expect the module to be at the root of the project folder, but if you have many that becomes a mess. build-module module-srcs/mymodule works perfectly fine.

回答2:

For Play 2, you can create new tasks using SBT, by following the documentation here:

http://www.scala-sbt.org/release/docs/Detailed-Topics/Tasks

In the context of a Play 2 generated Build.scala, it might look like this:

import sbt._
import Keys._
import play.Project._

object ApplicationBuild extends Build { 

  val appName         = "foo"
  val appVersion      = "1.0-SNAPSHOT"

  val appDependencies = Seq(
    // Add your project dependencies here,
    jdbc,
    anorm
  )

  val hello = TaskKey[Unit]("hello", "Prints 'Hello World'")

  val helloTask = hello := {
    println("Hello World")
  }

  lazy val main = play.Project(appName, appVersion, appDependencies).settings(
    helloTask
  )
}

回答3:

We are using Play Jobs for that kind of tasks.

@Every("1h")
public class WelcomeUser extends Job {

public void doJob() {
    List<User> newUsers = User.find("newAccount = true").fetch();
    for(User user : newUsers) {
        Notifier.sayWelcome(user);
    }
}

} 

or

Bootstrap job for tasks like db_migration :

@OnApplicationStart
public class Bootstrap extends Job {

public void doJob() {
    if(Page.count() == 0) {
        new Page("root").save();
        Logger.info("The page tree was empty. A root page has been created.");
    }
}

}

Have a look play documents : http://www.playframework.org/documentation/1.2.4/jobs