Add AndroidInjection.inject(View)

[rakshakhegde]

We have inject for Activity, Fragment, Receivers, etc., but one is required for custom views too.

[ronshapiro]

There is both a philosophical point and logistical/implementation point to be made here.

First, it's not fully clear to us that injecting views is the right thing to do. View objects are meant to draw, and not much else. The controller (in a traditional MVC pattern) is the one which can coordinate and pass around the appropriate data to a view. Injecting a view blurs the lines between fragments and views (perhaps a child fragment is really the appropriate construct instead?)

From the implementation perspective, there is also a problem in that there isn't a canonical way to retrieve the View's parent Fragments (if any), or Activity to retrieve a parent component. There have been hacks suggested to build in that relationship, but so far we haven't seen anything that seems to suggest that we could do this correctly. We could just call View.getContext().getApplicationContext() and inject from there, but skipping the intermediate layers without any option for something in between is inconsistent with the rest of our design, and probably confusing to users even if it works.

[trevjonez]

it might be possible to use https://github.com/InflationX/ViewPump in a way that allows you to use normal constructor injection for custom views as well, thus making special constructs for injecting a view unneeded at least in the context of dagger-android.

[ZakTaccardi]

it's not fully clear to us that injecting views is the right thing to do

while I would like to agree, fragments have their own issues, which has let to the rise of using custom views

[JakeWharton]

Custom views are not a replacement for fragments. You still need a coordination layer which is responsible for inflating, transitioning, and managing the stack. It should be that component's responsibility for injecting any views (or at the very least, providing the injector via the context hack).

[ZakTaccardi]

Custom views are not a replacement for fragments.

agreed, I was just pointing out the reason for the use case

[sevar83]

I currently inject Square's Coordinators via constructor and and I bind the coordinators to the custom views from inside the Activity. So the Activity becomes just a container for custom views and a coordination layer. Any opinions - is that correct?

[jemshit]

Would anyone elaborate the context hack approach?

[ronshapiro]

Not directly related, but discussed this a bit with @digitalbuddha here (and here's the gist)

[autonomousapps]

I'm open to being told this is bad design, but here's my situation and why I'd like the ability to easily inject Views.

My app's monetization strategy is based around subscriptions, and we have three tiers of membership -- call them Gold, Bronze, Silver.

I have a custom view, TierLayout, and a custom style attribute,

    <declare-styleable name="TierLayout">
        <!-- Gold | Silver | Bronze -->
        <attr name="tier" format="string"/>
    </declare-styleable>

I can set the tier on a TierLayout in XML.

In my custom view, I take a peak at the AttributeSet to see what the XML says and set the appropriate tier and set all the correct values relating to that programmatically. Of course, a Tier is a complex beast, so I get one via a TierFactory, which has an @Inject constructor.

In the current prod version of my app, I have a static reference to the relevant @Subcomponent, and I can call, e.g. DaggerUtil.INSTANCE.getUpgradeSubcomponent().inject(this /* TierLayout */). This gives me my TierFactory, from which I can call tierFactory.fromString(tierName /* from attrs */). I can do this right in the view's constructor.

I am in the fortunate (?) position of rewriting my app from scratch, and I've adopted dagger.android as the approach. This means I no longer have an easy static reference to that subcomponent, since I let the lib instantiate it for me.

@ContributesAndroidInjector abstract fun upgradeActivity(): UpgradeActivity

Please note, the existing prod code was written in Java, works well, and I'm basically just trying to port it over as-is to the new app (and in Kotlin, but that's an aside).

What is the recommended approach for getting an injectable object into my custom view?

[Zhuinden]

Time for us to just wait for Jake Wharton to solve this problem for us in https://github.com/square/AssistedInject 's inflation-inject 😛