Android ViewModelProvider() parameter error

Question

I am trying to get a value from the SharedViewModel class but the ViewModelProvider() is giving a parameter error when i am passing requireActivity() although the same initilization and assignment works in my fragments.

It is requiring "ViewModelStoreOwner" to be passed.

class CourseRepository(val app: Application) {

    private var viewModel: SharedViewModel = ViewModelProvider(requireActivity()).get(SharedViewModel::class.java)
    val courseData = MutableLiveData<List<Course>>()

    init {
        CoroutineScope(Dispatchers.IO).launch {
            callWebService()
        }
    }

    @WorkerThread
    suspend fun callWebService() {
        if (Utility.networkAvailable(app)) {
            val retrofit = Retrofit.Builder().baseUrl(WEB_SERVICE_URL).addConverterFactory(MoshiConverterFactory.create()).build()
            val service = retrofit.create(CourseService::class.java)
            val serviceData = service.getCourseData(viewModel.pathName).body() ?: emptyList()
            courseData.postValue(serviceData)
        }
    }
}

The purpose of the ViewModel here is because i am storing the Id of the selected RecyclerView item in order to send it to a server

score 0 · Answer 1 · answered Apr 29 '20 at 18:21

0

ViewModel instances are scoped to Fragments or Activities (or anything with a similar lifecycle), which is why you need to pass in a ViewModelStoreOwner to the provider to get a ViewModel from it. The point of ViewModels is that they will exist until the store they belong to is destroyed.

The requireActivity method doesn't work here, because you're not inside a Fragment.

Some things to consider here:

Do you really need ViewModel in this use case? Could you perhaps use just a regular class that you can create by calling its constructor?
Could you call this Repository from your ViewModel, and pass in any parameters you need from there?

answered Apr 29 '20 at 18:21

zsmb13

85,752
11
221
226

I am storing the ID of a selected RecyclerView item in the SharedViewModel class in order to send it through a http post request to filter my the SQL request on a server based on that selection – Apr 29 '20 at 18:32
i suppose i don' need to use the ViewModel, but how to i pass the Id of a selected RecyclerView item to a http post? – Apr 29 '20 at 18:33
Aren't you calling this repository from the ViewModel? Could you add this as a parameter to `callWebService`? – zsmb13 Apr 29 '20 at 18:38
i am not calling this respository from the view model – Apr 29 '20 at 18:53
What i want to do simply is, put the ReyclerViewItem Id into the getCourseData() function – Apr 29 '20 at 18:54
If i hardcode the value getCourseData("WEB001"), everything will work, the point is where do i store the retrieved Id of the selected RecyclerView Item in order to use it in the getCourseData() function? – Apr 29 '20 at 18:56

Android ViewModelProvider() parameter error

1 Answers1