How do I inject services into a Grails 3 command?

Question

In a Grails 3 app, how do I create a CLI command that leverages the app's Service and Domain classes?

The following did not work:

1. grails create-app test-grails3-angular-cmd --profile=angular
2. cd server
3. grails create-command MyExample

4. Implement MyExample:

   package test.grails3.angular.cmd
   
   import grails.dev.commands.*
   
   class MyExampleCommand implements GrailsApplicationCommand {
       def testService
   
       boolean handle() {
           testService.test()
           return true
       }
   }
   

5. grails create-service TestService

6. Implement TestService:

   package test.grails3.angular.cmd
   
   import grails.transaction.Transactional
   
   @Transactional
   class TestService {
   
       def test() {
           System.out.println("Hello, test service!")
       }
   }
   

   7. grails run-command my-example

Command execution error: Cannot invoke method test() on null object

How can I fix this?

I am using grails 3.3.0.M2.

Answer 1

MyExampleCommand is not a bean, I believe, where service can be injected. However, applicationContext is available in GrailsApplicationCommand (extends ApplicationCommand trait) which can be leveraged directly to get the service bean.

class MyExampleCommand implements GrailsApplicationCommand {

    boolean handle() {
        TestService testService = applicationContext.getBean(TestService)
        testService.test()
        return true
    }
}