When I use ```private val presenter: MyFeaturePres...

# koin-contributors

[Pedro Francisco de Sousa Neto]

When I use

private val presenter: MyFeaturePresenter by scope.inject()

Sometimes I got the crash

Caused by: java.lang.IllegalStateException: Fragment MyFeatureFragment{e397a0b} (4be986d3-729a-430d-86ee-ee1f657be059) not attached to an activity.
    at androidx.fragment.app.Fragment.requireActivity(Fragment.java:995)
    at org.koin.androidx.scope.FragmentExtKt.createFragmentScope(FragmentExt.kt:38)
    at org.koin.androidx.scope.FragmentExtKt$fragmentScope$1.invoke(FragmentExt.kt:50)
    at org.koin.androidx.scope.FragmentExtKt$fragmentScope$1.invoke(FragmentExt.kt:50)
    at kotlin.SynchronizedLazyImpl.getValue(LazyJVM.kt:74)

Why?
Because this value val is initializing in init from Kotlin fragment class.

How to avoid that

private val presenter: MyFeaturePresenter by lazy { scope.get() }

Is it the expected scenario to Koin lazy injection? 🤔

[Marcello Galhardo]

I’m not sure if Koin can avoid the requireActivity, after all the Fragment scope is a child from the Activity (see scope.linkTo in the code snippet you posted). Ignoring that would break the relationship between these two scopes.

Your proposed solution seems off. Aren’t inject lazy by default? Wrapping it inside a lazy should not change the behaviour. Check the last line of you stack trace SynchronizedLazyImpl.getValue.

What do you mean by “val is initialized in init”? Do you have a code sample for this statement?

[arnaud.giuliani]

You should use `AndroidScopeComponent`interface. this way just use the i`nject()` function, directly with the right scope

[arnaud.giuliani]

also look at ScopeFragment class

[Pedro Francisco de Sousa Neto]

I’m using ScopeActivity and ScopeFragment.
I don’t know yet how can reproduce this error, but I’m getting him sometimes in Firebase Crashlytics.

My guess: sometimes fragment is initializing “too fast” and is not attached to activity yet, so requireActivity() throws an exception.

[arnaud.giuliani]

About ScopeFragment it was one problem we had, that scope couldn’t be attached. In latest version it’s now solved

[Pedro Francisco de Sousa Neto]

hummm… I’m using 3.3.1, what version has it fixed?

[arnaud.giuliani]

you have it 😅

[arnaud.giuliani]

yes, your Activity is not yet attached

[arnaud.giuliani]

this mean you try to do something in a property that is initialized, before any onCreate call

[Pedro Francisco de Sousa Neto]

Yes, that’s the problem!

I’m doing something wrong in Koin usage? In my mind, that was a expected usage without crash, of course

[Pedro Francisco de Sousa Neto]

I wrote an article in Medium platform about this error and how can avoid it. But, the doubt about usage continues. 🙃

[Marcello Galhardo]

As a rule of thumb, there is no scenario in which you want to do any operation on a Fragment or Activity initialization time. Those components are created with an incomplete state, and only later will receive their respective contexts and required dependencies.

That is why they offer you an onCreate and that is where your Fragment initialization logic should go to ensure your Fragment is in a safe state.

If you use lazy, you should ensure it is only called "after" onCreated state is reached or you likely will crash.

[Pedro Francisco de Sousa Neto]

I agree totally with you @Marcello Galhardo. And inject in Koin usage is lazy and can handle this kind.

The problem is when you trigger a combination of createScope()->requireActivity() because you just added a fragmentScope(). And you’re not expecting that 😅.

[Pedro Francisco de Sousa Neto]

Backing to my initial question...

Is it the expected scenario to Koin lazy injection?

I think it’s not expected get a crash when you’re using scope.injection.

Maybe we need to improve docs, or annotate it with as throwable.

I really don’t know right know a better solution to help developers with Koin dev experience.

[arnaud.giuliani]

Maybe we need to improve docs, or annotate it with as throwable.

yes documentation can be improved on this point 👍

[Pedro Francisco de Sousa Neto]

Nice @arnaud.giuliani, I’ll do it ASAP! 😉

[arnaud.giuliani]

great, thanks 🙂 Ping me on the issue/PR