How to create a module with Play Framework

There are two approaches on how to create a Play Framework 2.3.x / 2.4.x module . The first is the module/sub-project the other is the code/sample-app. I guess both are good depending on how you want to approach the build of your project.

How to create a module the module/sub-project approach :

The idea behind this approach to follow the sbt multi-project approach to treat the module as a subproject. To instruct play how the build for the existing project will be executed, a build.sbt file is dropped within the submodule project.

Here are the steps on how to build your module/sub-project 

1. activator new module_sample_project
2. select play-java
3. cd module_sample_project
4. activator new sample_module
5. select play-java
6. mv sample_module to module
7. cd module
8. From within the module_sample_project/module/ folder
   • rm -r activator activator*.jar project test public
   • mv conf/routes conf/sample_module.routes
   • #rename the root project name to module in your build.sbt

             name := """sample_module"""
     
             version := "1.0-SNAPSHOT"
     
             lazy val module = (project in file("."))
                 .enablePlugins(PlayJava)
     
             scalaVersion := "2.11.6"
     
             libraryDependencies ++= Seq(
                   javaJdbc,
                   cache,
                   javaWs
             )
     
             // Play provides two styles of routers, one expects its actions to be injected, the
             // other, legacy style, accesses its actions statically.
             routesGenerator := InjectedRoutesGenerator
     

   • modify your folder structure so it can now make reference of the new module
     • mkdir -p app/sample_module/controllers app/sample_module/views
     • mv app/controllers app/sample_module/controllers
     • mv app/views app/sample_module/views
   • modify default controllers and views to make reference of the new structure
     • app/sample_module/controllers/Application.java should belong to the sample_module.controllers package
     • mv app/sample_module/views/index.scala.html app/sample_module/views/sample_module_index.scala.html
     • mv app/sample_module/views/main.scala.html app/sample_module/views/sample_module_main.scala.html
     • update your views to make reference of the views.
   • Update routes to make new routing reference

     #module/conf/sample_module.routes
     # Home page
     GET     /sample_module/    @sample_module.controllers.Application.index()
     

   • cd ../
9. edit your build.sbt to depend on the new module

       lazy val module = (project in file("module"))
           .enablePlugins(PlayJava)
   
       lazy val root = (project in file("."))
           .enablePlugins(PlayJava)
           .aggregate(module)
           .dependsOn(module)
   

10. Update sample-project reference to make new routing reference

    #conf/routes
     # Routes
    # This file defines all application routes (Higher priority routes first)
    # ~~~~
    
    # Home page
    GET        /           @controllers.Application.index()
    
    #Add sample_module routes
    ->         /           sample_module.Routes
    

11. run your app
    1. activator ~run

How to create a module with the code/sample-app approach :

This approach is very similar to the one described above by module/sub-project instructions. The main difference is that instead of pointing to a sub-project, the project is a code folder in the root of your git repo. The sample-app depends on the code code project. The instructions are the following :

1. mkdir module_sample_app
2. activator new module_sample_app
3. select play-java
4. mv module_sample_app code
5. cd code
6. Follow step 8 from module/sub-project 
7. cd ../
8. You will need to Publish Your Play Module to a Maven Repo repo your module so a dependency can be defined from a parallel project.
9. activator new sample-app
10. update your sbt to make reference of the module/sub-project module
11. follow step 10 from module/sub-project 

The source code for the play-module-sample can be found here.