Hello guys I have a question about `scope` and `v...

# koin

[quver]

Hello guys I have a question about scope and view models
I found https://github.com/InsertKoinIO/koin/issues/440#issuecomment-489583308
this solution but still have questions. Could you please hellp me.
I see that recommended way is to use.

private val viewModel: TabViewModel by viewModel { parametersOf(lifecycleScope.id) }

but what if I need global VM in many fragments with different lifecycle
What is best practice for this case. how I should create scope and that it between fragments?

UPD: googled laso sharedViewModel but it shared VM based on Actiity. and I need to share based on main fragment.

[aipok]

Usually you create VM inside the Activity and all the fragments just call sharedViewModel instance.
I also prefer to attach VM scope to activity.

[quver]

But what if I need scope less than Activity life.
For example it’s fragment + ViewPager with different fragments. and life should depends on this TabFragment life

[quver]

I see for the sharedViewModel activity is

owner: ViewModelStoreOwner

[aipok]

well, you can do same with parent fragment. You will create an instance inside parent fragment and all the child fragments will call for shared instance

[quver]

How exactly I should create it?
as I see it takes instance based on actiity or scope that eas provided
If I share test project could you please help me?

[aipok]

Sure

[quver]

I really appreciate it. Here is the test project
https://github.com/YvgenTroshchiy/TestKoinScope

[quver]

For now I see and option like this:

val myScopeInstance = val myScopeInstance = koin.createScope("myScopeId",named(¨MY_SCOPE¨)).createScope("myScopeId",named(¨MY_SCOPE¨))

have and instance of koin in the Application and then ask for scope that I need from this variable

[aipok]

can you please share what you want to see.. i don’t get it… while tab fragment is removed you want to clear the instance of VM?

[quver]

Exactly!

[aipok]

I could imagine it like this your module declare scope for TabFragment

val viewModelModule = module {
    scope(named<TabFragment>()) {
        viewModel { TabViewModel() }
    }
}

TabFragment will own VM like

private val viewModel: TabViewModel by lifecycleScope.viewModel(this)

And child fragments will get it like this

private lateinit var viewModel: TabViewModel

    override fun onAttach(context: Context) {
        super.onAttach(context)
        viewModel = requireParentFragment().lifecycleScope.getViewModel(requireParentFragment())
    }

As you can see below… each time while TabFragment is created, new instance of TabViewModel is created and passed to child fragments

viewModel in TabFragment: com.troshchiy.testkoinscope.TabViewModel@dee6937
TabFragment. 169590436
viewModel in Fragment 1: com.troshchiy.testkoinscope.TabViewModel@dee6937
Fragment1. 245425006
viewModel in Fragment 2: com.troshchiy.testkoinscope.TabViewModel@dee6937
Fragment2. 142329978
ViewModel. init: 228
viewModel in TabFragment: com.troshchiy.testkoinscope.TabViewModel@cc6fdfd
TabFragment. 13331186
viewModel in Fragment 1: com.troshchiy.testkoinscope.TabViewModel@cc6fdfd
Fragment1. 115849630
viewModel in Fragment 2: com.troshchiy.testkoinscope.TabViewModel@cc6fdfd

Hope this helps 😄

[quver]

@aipok Thank you a lot for help . this main “trick”

viewModel = requireParentFragment().lifecycleScope.getViewModel(requireParentFragment())

works great!