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androidmvvmandroid-recyclerviewviewmodelandroid-livedata

LiveData, View Models with Heterogeneous Recycler View

I am working on an android application which has a recycler view with multiple view types. It was originally a MVP based app, which I am trying to convert to MVVM based architecture with LiveData and ViewModels. I have a home screen with a list of different types of views inside a recycler view. Every view has its own ViewModel and corresponding Model, resulting it with a home screen having recycler view as a collection of different view models.

This is my first implementation of LiveData, so facing some issues with design. I see some options here -

  1. I create a parent HomeViewModel for my home activity which holds a LiveData object, consisting a list of different child ViewModels (representing different view types), making activity to its life cycle owner. Then I update each view(elements of recycler view) from one observer to that LiveData object.

  2. I create individual LiveData objects for every child view/view models and make home activity as life cycle owner for each model/live data and update their views independently from activity with respective observers.

  3. I create individual LiveData objects for every child view/view models and make respective view holder classes as their lifecycle owners and update individual views in respective holder classes.

Please help me suggesting the better way to deal with this or if there is any other approach other than the specified ones.

Thanks

Solution

  • I agreed to create a parent viewmodel such as "HomeViewModel", but I think the creation of viewmodel for each view type seems a little over-engineering, because every time you need to create a new view type, you need to create a new ViewModel, and I dont see any requirement for the view in recyclerview to have a dedicated viewmodel. In my perspective, the best approach is only have 1 viewmodel. Then I suggest you to implement adapter factory pattern for your recyclerview like in this article https://proandroiddev.com/writing-better-adapters-1b09758407d2 . If you have adapter factory pattern like that, you can generalize your recyclerview data, for example you can call it "Visitable" like the post above. Then, your viewmodel can hold just 1 livedata of visitable list, which observed by the fragment/activity.