Should I share my ViewModel across two fragments?












0















I'm attempting to follow Android best practices and use the latest recommended architecture components. You can see my attempt so far here: https://github.com/randroid88/TodayILearned



Right now the app's features are very limited.




  • It has a Room db for locally storing journal entries.

  • One fragment, HomeFragment, that lists all the entries

  • Another fragment, EntryEditorFragment, that creates new entries.

  • A ViewModel,
    EntryViewModel, that updates the data via a repository.


The problem is that only HomeFragment has access to EntryViewModel right now.



So in my current design, I pass the new entry text from EntryEditorFragment to HomeFragment via an argument bundle (using SafeArgs from the new Navigation Architecture Component), then HomeFragment creates the new entry via the EntryViewModel:



val safeArgs = HomeFragmentArgs.fromBundle(arguments!!)

    savePossibleNewEntry(safeArgs.entryText)



private fun savePossibleNewEntry(entryText: String) {

    entryViewModel!!.insert(EntryCreator().create(entryText))

}


This doesn't feel right.



Would it be better if EntryViewModel also had access to EntryEditorFragment?



In order to accomplish this, would I have to scope the ViewModel to the Activity as explained here on this blog?



What is the best practice here?






android-fragments android-architecture-components android-architecture-livedata android-mvvm android-architecture-lifecycle







share|improve this question























  • It does look like the official documentation recommends sharing the ViewModel: developer.android.com/topic/libraries/architecture/…

    – Randy
    Dec 31 '18 at 23:13
















0















I'm attempting to follow Android best practices and use the latest recommended architecture components. You can see my attempt so far here: https://github.com/randroid88/TodayILearned



Right now the app's features are very limited.




  • It has a Room db for locally storing journal entries.

  • One fragment, HomeFragment, that lists all the entries

  • Another fragment, EntryEditorFragment, that creates new entries.

  • A ViewModel,
    EntryViewModel, that updates the data via a repository.


The problem is that only HomeFragment has access to EntryViewModel right now.



So in my current design, I pass the new entry text from EntryEditorFragment to HomeFragment via an argument bundle (using SafeArgs from the new Navigation Architecture Component), then HomeFragment creates the new entry via the EntryViewModel:



val safeArgs = HomeFragmentArgs.fromBundle(arguments!!)

    savePossibleNewEntry(safeArgs.entryText)



private fun savePossibleNewEntry(entryText: String) {

    entryViewModel!!.insert(EntryCreator().create(entryText))

}


This doesn't feel right.



Would it be better if EntryViewModel also had access to EntryEditorFragment?



In order to accomplish this, would I have to scope the ViewModel to the Activity as explained here on this blog?



What is the best practice here?






android-fragments android-architecture-components android-architecture-livedata android-mvvm android-architecture-lifecycle







share|improve this question























  • It does look like the official documentation recommends sharing the ViewModel: developer.android.com/topic/libraries/architecture/…

    – Randy
    Dec 31 '18 at 23:13














0












0








0








I'm attempting to follow Android best practices and use the latest recommended architecture components. You can see my attempt so far here: https://github.com/randroid88/TodayILearned



Right now the app's features are very limited.




  • It has a Room db for locally storing journal entries.

  • One fragment, HomeFragment, that lists all the entries

  • Another fragment, EntryEditorFragment, that creates new entries.

  • A ViewModel,
    EntryViewModel, that updates the data via a repository.


The problem is that only HomeFragment has access to EntryViewModel right now.



So in my current design, I pass the new entry text from EntryEditorFragment to HomeFragment via an argument bundle (using SafeArgs from the new Navigation Architecture Component), then HomeFragment creates the new entry via the EntryViewModel:



val safeArgs = HomeFragmentArgs.fromBundle(arguments!!)

    savePossibleNewEntry(safeArgs.entryText)



private fun savePossibleNewEntry(entryText: String) {

    entryViewModel!!.insert(EntryCreator().create(entryText))

}


This doesn't feel right.



Would it be better if EntryViewModel also had access to EntryEditorFragment?



In order to accomplish this, would I have to scope the ViewModel to the Activity as explained here on this blog?



What is the best practice here?






android-fragments android-architecture-components android-architecture-livedata android-mvvm android-architecture-lifecycle







share|improve this question














I'm attempting to follow Android best practices and use the latest recommended architecture components. You can see my attempt so far here: https://github.com/randroid88/TodayILearned



Right now the app's features are very limited.




  • It has a Room db for locally storing journal entries.

  • One fragment, HomeFragment, that lists all the entries

  • Another fragment, EntryEditorFragment, that creates new entries.

  • A ViewModel,
    EntryViewModel, that updates the data via a repository.


The problem is that only HomeFragment has access to EntryViewModel right now.



So in my current design, I pass the new entry text from EntryEditorFragment to HomeFragment via an argument bundle (using SafeArgs from the new Navigation Architecture Component), then HomeFragment creates the new entry via the EntryViewModel:



val safeArgs = HomeFragmentArgs.fromBundle(arguments!!)

    savePossibleNewEntry(safeArgs.entryText)



private fun savePossibleNewEntry(entryText: String) {

    entryViewModel!!.insert(EntryCreator().create(entryText))

}


This doesn't feel right.



Would it be better if EntryViewModel also had access to EntryEditorFragment?



In order to accomplish this, would I have to scope the ViewModel to the Activity as explained here on this blog?



What is the best practice here?






android-fragments android-architecture-components android-architecture-livedata android-mvvm android-architecture-lifecycle




android-fragments android-architecture-components android-architecture-livedata android-mvvm android-architecture-lifecycle






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Dec 31 '18 at 21:43









RandyRandy

630514




630514













  • It does look like the official documentation recommends sharing the ViewModel: developer.android.com/topic/libraries/architecture/…

    – Randy
    Dec 31 '18 at 23:13



















  • It does look like the official documentation recommends sharing the ViewModel: developer.android.com/topic/libraries/architecture/…

    – Randy
    Dec 31 '18 at 23:13

















It does look like the official documentation recommends sharing the ViewModel: developer.android.com/topic/libraries/architecture/…

– Randy
Dec 31 '18 at 23:13





It does look like the official documentation recommends sharing the ViewModel: developer.android.com/topic/libraries/architecture/…

– Randy
Dec 31 '18 at 23:13












1 Answer
1






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oldest

votes


















1














The Android documentation suggested sharing a ViewModel for "a common case of master-detail fragments" so I decided to do the same for my case.



As suggested, I scoped the ViewModel to the Activity in both fragments:



entryViewModel = activity?.run {

        ViewModelProviders.of(this, EntryViewModelFactory(this.application, EntryRepository(this.application))).get(EntryViewModel::class.java)

    } ?: throw Exception("Invalid Activity")


Here's the commit where I made the change:
https://github.com/randroid88/TodayILearned/commit/e307bd3f238e68a399a2a1619438770d908a606d






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    1 Answer
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    active

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    1














    The Android documentation suggested sharing a ViewModel for "a common case of master-detail fragments" so I decided to do the same for my case.



    As suggested, I scoped the ViewModel to the Activity in both fragments:



    entryViewModel = activity?.run {
    
        ViewModelProviders.of(this, EntryViewModelFactory(this.application, EntryRepository(this.application))).get(EntryViewModel::class.java)
    
    } ?: throw Exception("Invalid Activity")


    Here's the commit where I made the change:
    https://github.com/randroid88/TodayILearned/commit/e307bd3f238e68a399a2a1619438770d908a606d






    share|improve this answer




























      1














      The Android documentation suggested sharing a ViewModel for "a common case of master-detail fragments" so I decided to do the same for my case.



      As suggested, I scoped the ViewModel to the Activity in both fragments:



      entryViewModel = activity?.run {
      
        ViewModelProviders.of(this, EntryViewModelFactory(this.application, EntryRepository(this.application))).get(EntryViewModel::class.java)
      
    } ?: throw Exception("Invalid Activity")


      Here's the commit where I made the change:
      https://github.com/randroid88/TodayILearned/commit/e307bd3f238e68a399a2a1619438770d908a606d






      share|improve this answer


























        1












        1








        1







        The Android documentation suggested sharing a ViewModel for "a common case of master-detail fragments" so I decided to do the same for my case.



        As suggested, I scoped the ViewModel to the Activity in both fragments:



        entryViewModel = activity?.run {
        
        ViewModelProviders.of(this, EntryViewModelFactory(this.application, EntryRepository(this.application))).get(EntryViewModel::class.java)
        
    } ?: throw Exception("Invalid Activity")


        Here's the commit where I made the change:
        https://github.com/randroid88/TodayILearned/commit/e307bd3f238e68a399a2a1619438770d908a606d






        share|improve this answer













        The Android documentation suggested sharing a ViewModel for "a common case of master-detail fragments" so I decided to do the same for my case.



        As suggested, I scoped the ViewModel to the Activity in both fragments:



        entryViewModel = activity?.run {
        
        ViewModelProviders.of(this, EntryViewModelFactory(this.application, EntryRepository(this.application))).get(EntryViewModel::class.java)
        
    } ?: throw Exception("Invalid Activity")


        Here's the commit where I made the change:
        https://github.com/randroid88/TodayILearned/commit/e307bd3f238e68a399a2a1619438770d908a606d







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Jan 1 at 4:47









        RandyRandy

        630514




        630514
































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