CODEWITHSUNDEEP
androidkotlinviewmodel
RAUL QUISPE
RAUL QUISPE

Reputation: 799

In kotlin how to use ViewModel With ViewModelProvider.AndroidViewModelFactory?

In my current project I use the next line:

mViewModel = ViewModelProviders.of(this).get(MainViewModel::class.java)

For instance a ViewModel but in https://developer.android.com/reference/android/arch/lifecycle/ViewModelProviders.html#ViewModelProviders() recommend use ViewModelProvider.AndroidViewModelFactory because ViewModelProviders() was deprecated in API level 1.1.0.

any idea for this purpose?

Upvotes: 6

Views: 7885

Answers (6)

bwoh
bwoh

Reputation: 96

You can use AndroidViewModelFactory like this:

mViewModel = ViewModelProvider(this,
            ViewModelProvider.AndroidViewModelFactory(application))
            .get(MainViewModel::class.java)

Upvotes: 2

bwoh
bwoh

Reputation: 96

  1. Open build.gradle(Module:~.app)

  2. Edit appcompat version to 1.3.0-alpha02

     implementation 'androidx.appcompat:appcompat:1.3.0-alpha02'

Upvotes: 1

zsmb13
zsmb13

Reputation: 89668

EDIT: The original question is now irrelevant, as you should no longer use the ViewModelProviders utility class. Instead, you should create a ViewModelProvider instance like so:

val viewModel = ViewModelProvider(thisFragment).get(MyViewModel::class.java)

Original answer below.

ViewModelProviders is just a utility class with static methods, there's no need to instantiate it (there are no instance methods in it anyway), so the constructor being deprecated shouldn't be a concern.

The way you use it is by calling its appropriate of method for your use case, passing in a Fragment or Activity, and then calling get on the ViewModelProvider it returns:

val viewModel = ViewModelProviders.of(thisFragment).get(MyViewModel::class.java)

If you don't provide your own factory in the second parameter of the of method, AndroidViewModelFactory will be used by default. This implementation can either create ViewModel subclasses that have no constructor parameters, or ones that extend AndroidViewModel, like such:

class MyViewModel(application: Application) : AndroidViewModel(application) {

    // use application

}

Upvotes: 4

sm abbas
sm abbas

Reputation: 1028

If you had a simple ViewModel extending AndroidViewModel without any additional constructor parameters, its as follows

  1. Extend AndroidViewModel without any additional constructor parameters
class FooViewModel(application: Application) : AndroidViewModel(application) {}
  1. Create View Model in Activity
val viewModel = ViewModelProvider(this).get(FooViewModel::class.java)

But if you had a ViewModel extending AndroidViewModel with any additional constructor parameters, its as follows

  1. Extend AndroidViewModel with any additional constructor parameters
class FooViewModel(application: Application, foo: Foo) : AndroidViewModel(application) {}
  1. Create a new view model factory extending ViewModelProvider.AndroidViewModelFactory
class FooViewModelFactory(val application: Application, val foo: Foo): ViewModelProvider.AndroidViewModelFactory(application) {

            override fun <T : ViewModel?> create(modelClass: Class<T>): T {
                return FooViewModel(
                    application, foo
                ) as T
            }

     }
  1. Create View Model in Activity
val viewModel = ViewModelProvider(this, FooViewModelFactory(application, foo)).get(FooViewModel::class.java)

Upvotes: 9

lior_13
lior_13

Reputation: 609

So, it is quite simple:

// This is the deprecated way to create a viewModel.
viewModel = ViewModelProviders.of(owner).get(MyViewModel::class.java)

//This is the deprecated way to create a viewModel with a factory.
viewModel = ViewModelProviders.of(owner, mViewModelFactory).get(MyViewModel::class.java)

// This is the new way to create a viewModel.
viewModel = ViewModelProvider(owner).get(MyViewModel::class.java)

//This is the new way to create a viewModel with a factory.
viewModel = ViewModelProvider(owner, mViewModelFactory).get(MyViewModel::class.java)

Upvotes: 1

Su Zhenpeng
Su Zhenpeng

Reputation: 224

you can try this code

    ViewModelProvider.AndroidViewModelFactory.getInstance(application).create(UserViewModel::class.java)

Upvotes: 3

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