CODEWITHSUNDEEP
javadependency-injectionplayframeworkguice
NSF
NSF

Reputation: 2549

How to implement and test mapbinding correctly with Guice and Play framework

I just started using Guice and Play so I guess this is a long but basic question. I checked the guide here: http://eng.42go.com/play-framework-dependency-injection-guice/ but I don't know why my code fails.

First I have a global injector:

public class GlobalInjector {
    private static Injector guiceInjector;
    private static List<AbstractModule> modules = new ArrayList<AbstractModule>();

    public static Injector getInjector() {
        return guiceInjector;
    }

    public static loadModules() {
        guiceInjector = Guice.createInjector(modules);
    }

    public static addModule(AbstractModule module) {
        modules.add(module);
    }
}

Also I have added Guice to Play by extending the GlobalSettings class (also modified application.global)

public class GuiceExtendedSettings extends GlobalSettings {
    @Override
    public void onStart(Application app) {
        GlobalInjector.loadModules();
    }

    @Override
    public <A> A getControllerInstance(Class<A> controllerClass) {
         return GlobalInjector.getInjector().getInstance(controllerClass);
    }
}

Then I have my test module acting as a plugin in Play (some required methods are omitted as they do nothing in this piece):

public class TestModule extends AbstractModule implements Plugin {

    @Override
    public void configure() {
        // Worker is a simple class
        Worker worker = new SimpleWorker();
        MapBinder<String, Worker> mapBinder = MapBinder.newMapBinder(binder(), String.class, Worker.class);
        mapBinder.addBinding(worker.getName()).toInstance(worker);
    }

    @Override
    public void onStart() {
        GlobalInjector.addModule(this);
    }
}

Worker is a simple interface:

public interface Worker {
    public String getName();
    public String getResult();
}

SimpleWorker:

public class SimpleWorker implements Worker {
    public String getName() {
        return "SimpleWorker";
    }

    public String getResult() {
        return "works";
    }
}

And here is the code piece showing the controller logic: nothing but just print all worker results in the map injected

public class TestController extends Controller {
     @Inject
     Map<String, Worker> workers;

     public Result showWorkers() {
         StringBuilder sb = new StringBuilder();
         for (Worker worker : workers) {
             sb.append(worker.getName() + ": " + worker.getResult() + "</br>");
         }
         return ok(sb.toString()).as("text/html");
     } 
}

OK. To make this work, I put the following line in play.plugins:

100:test.TestModule

My idea is: Play loads the plugin (TestModule) -> TestModule adds itself to the GlobalInjector -> GlobalInjector creates Guice injector -> Guice injects the map to the controller

However the result was Guice didn't inject the map. The map is still null.

Also how should I test it? (i.e. how can I inject different workers to that map? I hard-coded that part in the above code. But I'm looking for a dynamic way by using different modules.)

public class Test {
    @Test
    public void testInjector() {
        running(fakeApplication(), new Runnable() {
           public void run() { 
               // how can I inject using different modules here?
           }
        });

    }
}

Upvotes: 0

Views: 1273

Answers (1)

Keith Blaha
Keith Blaha

Reputation: 21

You need to use the fakeApplication helper method that allows you to specify both your global settings object and additional plugins. See http://www.playframework.com/documentation/api/2.1.x/java/play/test/Helpers.html#fakeApplication(java.util.Map,%20java.util.List,%20play.GlobalSettings) for more information.

But basically, your test should look something like:

public class Test {
    @Test
    public void testInjector() {
       Map<String, Object> config = new HashMap<String, Object>();
       // add any additional config options, e.g. in-memory db
       List<String> plugins = new ArrayList<String>();
       plugins.add("full.package.name.TestModule");
       GlobalSettings global = null;
       try {
           global = (GlobalSettings) Class.forName("full.package.name.GuiceExtendedSettings").newInstance();
       } catch(Exception e) {}

       running(fakeApplication(config, plugins, global), new Runnable() {
           public void run() { 
               // do some assertions
           }
        });
    }
}

You also need to make sure that guice instantiates the test controller or the workers map won't be injected.

Upvotes: 1

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