Using Gin to Inject Multiple Views

Question

I'm attempting to put together a multi-project application, wherein one of the sub-projects has multiple views for a single presenter. I am using Gin to inject views into my presenters.

The sub-project contains the presenter and the 2 different views. I have 2 separate gin modules, each binding one of the views to the view interface.

As per Thomas Broyer's suggestion on the answer to this post, my Ginjectors are wrapped in a "holder" class that calls the GWT.create on the particular ginjector. The appropriate holder is configured in the gwt.xml file using a replace-with statement.

When I run my project in Dev Mode, I see the alternate view appear as I expect it to. However, when I compile the project, I still only get the default view. Also, only 6 permutations (I would expect more on account of the replace-with logic), and I do not get the view I expect in the different scenarios.

Here is some code to illustrate.

Subproject.gwt.xml contains this:

<replace-with class="com.example.GinjectorDesktopHolder">
    <when-type-is class="com.example.GinjectorHolder" />        
</replace-with>

<replace-with class="com.example.GinjectorTabletHolder">
    <when-type-is class="com.example.GinjectorHolder" />
    <when-property-is name="formfactor" value="tablet" />
</replace-with>

The "formfactor" variable is defined in a gwt.xml copied verbatim from GWT's mobilewebapp sample project.

The Holder classes look like this:

public abstract class GinjectorHolder {
    public abstract Ginjector getGinjector();
}

public class GinjectorTabletHolder extends GinjectorHolder {
    @Override
    public Ginjector getGinjector() {
        return GWT.create(GinjectorTablet.class);
    }   
}

public class GinjectorDesktopHolder extends GinjectorHolder {
    @Override
    public Ginjector getGinjector() {
        return GWT.create(GinjectorDesktop.class);
    }
}

My Ginjectors look like this:

public interface MyGinjector {
    MyView getView();
    EventBus getEventBus();
}

@GinModules({ModuleDesktop.class})
public interface GinjectorDesktop extends Ginjector, MyGinjector {}

@GinModules({ModuleTablet.class})
public interface GinjectorTablet extends Ginjector, MyGinjector {}

My modules look like this:

public class ModuleDesktop extends AbstractGinModule {
    @Override
    protected void configure() {
        bind(MyPresenter.View.class).to(DesktopView.class);
    }
}

public class ModuleTablet extends AbstractGinModule {
    @Override
    protected void configure() {
        bind(MyPresenter.View.class).to(TabletView.class);
    }
}

And finally, in my presenter proxy, basically the entry point into this particular sub-project, I have this line:

GinjectorHolder holder = GWT.create(GinjectorHolder.class);
MyGinjector ginjector = holder.getGinjector();      

As mentioned earlier, when I run in Dev Mode and put in breakpoints, I can see the appropriate GinjectorHolder is created. The FormFactor.gwt.xml (linked above) provides a switch for using a URL param to switch to the context you'd like to see. So I can do formfactor=tablet in the URL and the Tablet Ginjector Holder is created.

Answer 1

As mentioned in the comments, removing the line

<collapse-property name="formfactor" values="*"/>

leads to the expected increase in the number of permutations.

Still, it's mysterious, why this is necessary, because usually it should be possible to collapse any properties you like - it just means, that each browser has to download more code, but should still get everything it needs. Could be a bug.

Answer 2

First of all instead of mapping view to viewimpl you can bind it to viewprovider, and then based on user-agent values you can return the appropriate instance to bind to.