CODEWITHSUNDEEP
androidandroid-livedataandroid-viewmodel
Azizjon Kholmatov
Azizjon Kholmatov

Reputation: 1256

LiveData not working until user performs some action

My LiveData is not working.

ViewModel: 

 private var _email = MutableLiveData<String>()

 fun setEmail(){
    _email.postValue("[email protected]")
 }

 fun getEmail(): LiveData<String>{
     return _email
 }

Fragment's onViewCreated method :

 mViewModel.getEmail().observe(viewLifecycleOwner, Observer {
    tvEmail.text = it
 })

 mViewModel.setEmail() //Trying to post data to my LiveData.

The above code is not working as tvEmail is not chaning.

However, if I trust a button for posting data to LiveData like this, it is working:

 //Inside fragment again
 button.setOnClickListener {
     mViewModel.setEmail()
 }

When user clicks button, text in tvEmail is changing. If user does not click, nothing is happening. What am I missing here?

Edit:

I have just tested the code with Activity. Surprisingly, for Activitys it is working but not for Fragments.

Upvotes: 0

Views: 54

Answers (1)

Divakar Murugesh
Divakar Murugesh

Reputation: 1287

@Azizjon Kholmatov - Best practice you can write your code inside the "onActivityCreated" function

please refer this. If you still having the problem let me know in comments section. I am happy to help. :)

class MainFragment : Fragment() {

    companion object {
        fun newInstance() = MainFragment()
    }

    private lateinit var viewModel: MainViewModel

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
        return inflater.inflate(R.layout.main_fragment, container, false)
    }

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)

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

        viewModel.getEmail().observe(viewLifecycleOwner, Observer {
            tvEmail.text = it
        })

        viewModel.setEmail("[email protected]")

        button.setOnClickListener {
            viewModel.setEmail("[email protected]")
        }
    }
}

And ViewModel class as follows

class MainViewModel : ViewModel() {

    private var _email = MutableLiveData<String>()

    fun setEmail(email: String = "[email protected]") {
        _email.postValue(email)
    }

    fun getEmail(): LiveData<String> {
        return _email
    }
}

Upvotes: 1

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