Recyclerview does not refresh MVVM

Question

I am new using MVVM and Kotlin. I decided to use them in a new project, I do not know what is wrong. I am using Hilt MVVM and ViewModel etc. hopefully you can help me

This is the Fragment who request the data from the db, when somebody presses the fab_add_check button. I open a new activity to insert a new row into the db, I able to check the db. so I know insert works, however why the ui is not updated?

@ExperimentalCoroutinesApi
@AndroidEntryPoint
class CheckFragment : BaseFragment() {

    private lateinit var checkAdapter: CheckAdapter

    private val checkViewModel: CheckViewModel by viewModels()

    companion object {
        private const val ARG_FLAG = "ARG_FLAG"
        private const val ARG_CHECK_STATUS = "ARG_CHECK_STATUS"

        @JvmStatic
        fun newInstance(isAllFrag: Boolean, checkStatus: CheckStatus) = CheckFragment().apply {
            arguments = Bundle().apply {
                putBoolean(ARG_FLAG, isAllFrag)
                putString(ARG_CHECK_STATUS, checkStatus.name)
            }
        }
    }

    override fun setLayout() = R.layout.fragment_check

    override fun initFragment(view: View) {
        if (requireArguments().getBoolean(ARG_FLAG)) view.fab_add_check.show()
        else view.fab_add_check.hide()
        
        view.check_rv?.layoutManager = LinearLayoutManager(requireContext())

        view.fab_add_check.setOnClickListener {
            startActivity(Intent(context, ScanCheckActivity::class.java))
        }

        getChecks(requireArguments().getString(ARG_CHECK_STATUS))
    }

    //Get check from the db
    private fun getChecks(checkStatus: String?) {
        checkViewModel.setCheckStatus(checkStatus)
        checkViewModel.checks.observe(this, Observer {
            checkAdapter = CheckAdapter(it, requireContext())
            view?.check_rv?.adapter = checkAdapter
        })
    }

}

//Here the ViewModel

@ExperimentalCoroutinesApi
class CheckViewModel 
@ViewModelInject constructor(private val checkRepository: CheckRepository) : ViewModel(){

    private val _checks = MutableLiveData<List<Check>>()
    val checks: LiveData<List<Check>>
        get() = _checks

    fun saveCheck(check: Check) {
        viewModelScope.launch {
            checkRepository.insertCheck(check)
        }
    }

    fun setCheckStatus(checkStatus: String?) {
        viewModelScope.launch {
            _checks.postValue(checkRepository.getChecksByStatus(checkStatus!!))
        }
    }

}

//Repository

class CheckRepository @Inject constructor(
    private val db: AppDataBase,
    private val checkEntityMapper: CheckEntityMapper
) {

 
    //From db
    fun getChecksByStatus(checkStatus: String) =
        if (checkStatus == CheckStatus.UNKNOWN.name) checkEntityMapper.mapFormEntityList(db.checkDao().getChecks())
        else checkEntityMapper.mapFormEntityList(db.checkDao().getChecksByStatus(checkStatus))

    
    fun insertCheck(check: Check) = db.checkDao().insertCheck(checkEntityMapper.mapToEntity(check))
}

score 0 · Answer 1 · answered Jul 22 '20 at 10:48

you can keep the incoming data as livedata or mutablelivedata,you can do the update process wherever you listen.

class NewsAdapter(
private val setOnClickListener: (NewsModel) -> Unit) : ListAdapter<NewsModel,NewsHolder>(DiffCallBack()) { override funonCreateViewHolder(parent:ViewGroup, viewType: Int): NewsHolder {

    val newsCardBinding: NewsCardBinding =
        NewsCardBinding.inflate(LayoutInflater.from(parent.context))

    return NewsHolder(newsCardBinding)

}

override fun onBindViewHolder(holder: NewsHolder, position: Int) {
    holder.bind(getItem(position), setOnClickListener)
}

class DiffCallBack : DiffUtil.ItemCallback<NewsModel>() {
    override fun areItemsTheSame(oldItem: NewsModel, newItem: NewsModel): Boolean =
        oldItem.title == newItem.title

    override fun areContentsTheSame(oldItem: NewsModel, newItem: NewsModel): Boolean =
        oldItem == newItem
}}

//Activity-Fragment
pharmacyViewModel.getPharmacy().observe(viewLifecycleOwner, Observer { list -(recyclerView.adapter as PharmacyAdapter).submitList(list)})

OR - normal adapter with

// in Adapter

fun updateList(list: ArrayList) {this.list.apply {clear() addAll(list)}}

//activity-fragment

fun updateList(list: ArrayList) { this.newsAdapter.apply {updateList(list)notifyDataSetChanged()}}

newsViewModel.getData().observe(viewLifecycleOwner, Observer { newsList->updateList(newsList as ArrayList) })

Recyclerview does not refresh MVVM

1 Answers1