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#compose
Title
# compose
u
ursus
10/22/2023, 12:15 AMAnyone have ViewModels that work in compose but *dont have the android*/android architecture dependency?
It is possible to mimic what it does, with my own type, right? (to survive orientation changes + stay alive while on backstack)
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Alejandro Rios
10/22/2023, 12:29 AMYou might wanna look for precompose or decompose libraries, they offer a way to use view models for other targets
u
ursus
10/22/2023, 12:30 AMbut, why does it have android dependency at all? ViewModel is basically just a interface
its the retaining bit that has the android dependency, right?
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Ian Lake
10/22/2023, 5:41 AMYou might look at https://github.com/rickclephas/KMM-ViewModel
And star the official feature request for making ViewModel itself multiplatform: https://issuetracker.google.com/issues/214568825
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Arjan van Wieringen
10/22/2023, 11:26 AMFor our own HTML and Desktop projects we just rolled our own viewmodel. It’s pretty easy and works well with a good DI framework
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Arkadii Ivanov
10/23/2023, 9:00 AMI believe the AndroidX ViewModel class itself doesn't depend on anything Android-specific. It only depends on AndroidX Annotations (that are already multiplatform) and a bunch of Java things. See here: https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:lifecycle/lifecycle-viewmodel/src/main/java/androidx/lifecycle/ViewModel.java
I think the integration with the platform is Android-specific, that's why the entire library is currently only for Android.
u
ursus
10/23/2023, 9:10 AMyea so if they broke it apart into 2 artifacts (jvm + android), it should be able multiplatform ready, right?
well, ready-ish, obviously jvm is not multiplatform, but shedding android is a start
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Arkadii Ivanov
10/23/2023, 9:12 AMPerhaps, but would there be any benefit to just having the ViewModel class? You can create your own expect/actual class, and typealias it to AndroidX ViewModel for Android, and just simple class for other platforms. But it's the integration with the platform and navigation that does the magic.
u
ursus
10/23/2023, 9:13 AMwell, host junit tests for start
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Arkadii Ivanov
10/23/2023, 9:13 AMTypealias should work, I guess
u
ursus
10/23/2023, 9:13 AMhence why I have my own ViewModel type even on android
but that was dependant on Conductor handling config changes retaining, which is now obsolete with compose navigation
typealias?
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Arkadii Ivanov
10/23/2023, 9:17 AMYep,
expect class ViewModelactual typealias ViewModel = androidx.lifecycle.ViewModelu
ursus
10/23/2023, 9:19 AMsure, but there are thing I dont like about their shape
how do you test it though? on emulator only?
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Arkadii Ivanov
10/23/2023, 9:30 AMIt should be testable locally with Junit, there are no Android dependencies.
u
ursus
10/23/2023, 9:31 AMhmm since it does pull in android, but doesnt touch any android apis, means it will work?
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Arkadii Ivanov
10/23/2023, 9:44 AMThe library is only for Android, perhaps because there are things that depend on Android platform APIs. But the ViewModel class itself is a pure Java class. You can try, it should work.
Unless I'm missing something, but looking at the code there is nothing Android-related.
u
ursus
10/23/2023, 9:47 AMthats good to know it will work for teste
regardless their shape is wrong, the "do work" in init bit, makes flows untestable, if they conflate
you need to instantiate the class, then setup observer, then cause the testable bit.. and here you cant since its all in ini
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Arkadii Ivanov
10/23/2023, 9:48 AMWhat's "do work"?
u
ursus
10/23/2023, 9:49 AMwell, setup flows forexample
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Arkadii Ivanov
10/23/2023, 9:49 AMI don't get it
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ursus
10/23/2023, 9:49 AMunless you assume nothing is synchronous.
but thats a dispatcher detail
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Arkadii Ivanov
10/23/2023, 9:50 AMThe AndroidX ViewModel class is just a simple and almost empty class. It only contains some logic for closing.
u
ursus
10/23/2023, 9:51 AMwell if in the init you subscribe a flow that emits 2 values, youd only see the latest
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Arkadii Ivanov
10/23/2023, 9:51 AMThat looks unrelated to ViewModel class, as there is nothing about coroutines in there.
u
ursus
10/23/2023, 9:51 AMbasically its missing some sort of "setup" lifecycle method, but yea I could probably bolt that on myself
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Arkadii Ivanov
10/23/2023, 9:52 AMSo yeah, you can do something for your needs.
u
ursus
10/23/2023, 9:52 AMyea didnt occur to me
btw what about the
viewModelScopelooking at the sources I dont see it but how else could they have.. a stored property extension..oxymoron
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Arkadii Ivanov
10/23/2023, 10:05 AMYeah, it should be in a separate ktx artifact
I think you can just write your own KMP variant, in a similar way
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ursus
10/23/2023, 10:06 AMhow do they add a stored property as a extension.. thats not possible, is it?
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Arkadii Ivanov
10/23/2023, 10:16 AMu
ursus
10/23/2023, 10:17 AMoh its the tagging hacks
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