CODEWITHSUNDEEP
androidmvvm
aqellaa
aqellaa

Reputation: 51

Is it possible to call ViewModel methods from fragments through an Activity or is it a bad practice?

I have an Activity and 4 fragments in it. At first I wanted to do for each fragment of the ViewModel. But the situation is such that I also need ViewModel for Activity. I want to know if it would be an error to make the ViewModel just for the Activity and call the necessary methods from the fragments using getActivity? For example, call getActivity().myViewModel.callMethod() at fragment? Wouldn't this approach be wrong?

Upvotes: 1

Views: 1788

Answers (1)

ehart
ehart

Reputation: 111

Yes, you can use the ViewModel of the Activity at a fragment, but not like that getActivity().myViewModel.callMethod(). It should be like this

YourViewModel viewModel = ViewModelProviders.of(getActivity()).get(YourViewModel.class);

And it's a good practice to share data between fragments.

Official doc of Google says

That way, when the fragments each get the ViewModelProvider, they receive the same SharedViewModel instance, which is scoped to this activity.

This approach offers the following benefits:

  • The activity does not need to do anything, or know anything about this communication.
  • Fragments don't need to know about each other besides the SharedViewModel contract. If one of the fragments disappears, the other one keeps working as usual.
  • Each fragment has its own lifecycle, and is not affected by the lifecycle of the other one. If one fragment replaces the other one, the UI continues to work without any problems.

Upvotes: 2

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