我从使用 MVVM 的改造中得到多重响应 - kotlin

Question

I just started learning MVVM and I am unable to find out why I am getting response from retrofit multiple times. I am following the videos on how to implement MVVM in kotlin and I would be very glad if you suggested better approach to this.

This is the Repository (I am using jsonplaceholder to get users):

class HelpersRepository(val application: Application) {
val showProgress = MutableLiveData<Boolean>()
val helpersList = MutableLiveData<List<Helpers>>()

fun getAllHelpers() {
    showProgress.value = true

    val destinationService  = ServiceBuilder.buildService(HelpersNetwork::class.java)
    val requestCall = destinationService.getHelpers()
        requestCall.enqueue(object : Callback<List<Helpers>>{
        override fun onResponse(call: Call<List<Helpers>>, response: Response<List<Helpers>>) {
                helpersList.value = response.body()
                Log.d("response", "${helpersList.value}")
                showProgress.value = false

        }

        override fun onFailure(call: Call<List<Helpers>>, t: Throwable) {
            showProgress.value = false
            Toast.makeText(application, "Error while fetching the data", Toast.LENGTH_SHORT).show()
        }

    })
}}

This is the ViewModel :

class HelpersViewModel(application: Application) : AndroidViewModel(application) {
    private val repository = HelpersRepository(application)
    val showProgress : LiveData<Boolean>
    val helpersList : LiveData<List<Helpers>>


    init {
        this.showProgress = repository.showProgress
        this.helpersList = repository.helpersList
    }

    fun getAllHelpers() {
            repository.getAllHelpers()
    }
}

And this is my Fragment :

class HelpersFragment : Fragment() {
    private lateinit var viewModel: HelpersViewModel
    private lateinit var adapter: HelpersAdapter

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {

        return inflater.inflate(R.layout.fragment_helpers, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        viewModel = ViewModelProvider(this).get(HelpersViewModel::class.java)
        adapter = HelpersAdapter(requireContext())
        rv_helpers.adapter = adapter

        viewModel.getAllHelpers()

        viewModel.showProgress.observe(viewLifecycleOwner, Observer {
            if (it) {
                pb_helpers.visibility = View.VISIBLE
            } else {
                pb_helpers.visibility = View.GONE
            }
        })

        viewModel.helpersList.observe(viewLifecycleOwner, Observer {
            adapter.setHelpersList(it)
        })
    }
}

when viewModel.getAllHelpers() gets called in the fragment, the log displays the response three times (I am unable to copy the log as StackOverflow considers it as a spam).

PS If I put viewModel.getAllHelpers() inside a setOnclickListener on button, then it only fetches data one time.

I have searched everywhere but was unable to get the answer fitted to my question. I realize I am doing something wrong, but can't figure out exactly what

Answer 1

I finally figured out that my problem was coming from choosing dark mode in MainActivity. Turns out you must call:

AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO)

before setContentView() in onCreate