how to use the same mutableLiveData in ViewModel from fragment and dialog fragment

Question

I have a ViewModel, that I used in Fragment and DialogFragment. In Dialog Fragment, I try to update MutableLiveData value in Dialog Fragment and then use that value from MutableLiveData in my Fragment. as I check In Dialog Fragment I have data inside MutableLiveData but when trying to access that data inside fragment I got null. may please guide me on how to fix this problem?

in ViewModel:

val width = MutableLiveData<String>()
val height = MutableLiveData<String>()
val length = MutableLiveData<String>()

in DialogFragment:

vModel.width.value = "6"
vModel.height.value = "6"
vModel.length.value = "6"

and in my fragment that when I try to access data from MutableLiveData:

println(vModel.width.value)
println(vModel.height.value)
println(vModel.length.value)

this is my BaseFragment:

abstract class BaseFragment<B : ViewDataBinding, V : BaseViewModel>(
    private val layout: Int,
    private val viewModel: V
) : Fragment() {

    private lateinit var v: View
    protected lateinit var binding: B
    protected lateinit var vModel: V


    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        super.onCreateView(inflater, container, savedInstanceState)
        binding = DataBindingUtil.inflate(inflater, layout, container, false)
        binding.lifecycleOwner = viewLifecycleOwner
        this.vModel = viewModel


        initVariables()
        initObserves()
        initViews()

        return binding.root
    }

    abstract fun initVariables()
    abstract fun initObserves()
    abstract fun initViews()

}

this is my BaseDialogFragment:

abstract class BaseDialogFragment<B : ViewDataBinding, V : BaseViewModel>(
    private val layout: Int,
    private val viewModel: V
) : DialogFragment() {

    private lateinit var v: View
    protected lateinit var binding: B
    protected lateinit var vModel: V


    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        super.onCreateView(inflater, container, savedInstanceState)
        binding = DataBindingUtil.inflate(inflater, layout, container, false)
        binding.lifecycleOwner = viewLifecycleOwner
        this.vModel = viewModel


        initVariables()
        initObserves()
        initViews()

        return binding.root
    }

    abstract fun initVariables()
    abstract fun initObserves()
    abstract fun initViews()

}

You should post whole story. Looks like your view model is not exactly shared view model. — ror, Jun 16 '20 at 07:05

score 1 · Answer 1 · answered Jun 16 '20 at 07:19

1

Make sure you load your ViewModel with activity context so one instance will be shared with all fragments, and not be recreated for each one

something like this

val viewModel by activityViewModels<MainViewModel> ()

answered Jun 16 '20 at 07:19

Sergey

394
1
12

I use this BaseFragment and BaseDialogFragment. is it wrong? – Mehrdad Dolatkhah Jun 16 '20 at 07:43
1

you can check this https://developer.android.com/topic/libraries/architecture/viewmodel take a look at "Share data between fragments", – Sergey Jun 16 '20 at 08:04

how to use the same mutableLiveData in ViewModel from fragment and dialog fragment

1 Answers1