Firebase doesn't load data at first time

Question

I'm trying to load data from Firebase into a RecyclerView, however nothing shows up until I reload my fragment.

This is my onCreate method in SubjectsFragment:

viewModel.subjectsListLiveData.observe(
            this,
            Observer { list ->
                subjectsAdapter.swapSubjectsList(list)
                if (subject_list != null && list.size != 0) Animations.runLayoutAnimation(
                    subject_list
                )
            })
viewModel.lessonsListLiveData.observe(
            this,
            Observer { list ->
                subjectsAdapter.swapLessonsList(list)
                if (subject_list != null && list.size != 0) Animations.runLayoutAnimation(
                    subject_list
                )
            })

This is SubjectsFragmentViewModel:

    private val subjectsList = MutableLiveData<ArrayList<Subject>>()
    val subjectsListLiveData: LiveData<ArrayList<Subject>>
        get() = subjectsList

    private val lessonsList = MutableLiveData<ArrayList<Lesson>>()
    val lessonsListLiveData: LiveData<ArrayList<Lesson>>
        get() = lessonsList

    init {
        loadSubjects()
        loadLessonsForSubjects()
    }

    fun loadSubjects() {
        GlobalScope.launch {
            val subjects = FirebaseUtils.loadAllSubjects()
            subjectsList.postValue(subjects)
        }
    }

    fun loadLessonsForSubjects() {
        GlobalScope.launch {
            val lessons = FirebaseUtils.loadAllLessons()
            lessonsList.postValue(lessons)
        }
    }

I don't have any problems once I reload the fragment. Could someone please explain to me what I'm doing wrong?

Did my answer help you?

MMG
– MMG

2020-03-16 13:01:53 +00:00
Commented Mar 16, 2020 at 13:01 — MMG
– MMG, Commented Mar 16, 2020 at 13:01

Espera Awo · Accepted Answer · 2020-03-16 14:17:18Z

1

Try using setValue directly. But you may be right, using postValue from a background thread is the way it should be done.

Also, attach your observers in onActivityCreated()

answered Mar 16, 2020 at 14:17

Espera Awo

405 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

milancodes Over a year ago

Thanks! Attaching my observers in onActivityCreated solved the problem for me!

milancodes Over a year ago

If anyone's facing the same issue, another problem of mine was that I used Firebase as functions that return values - see more here: stackoverflow.com/a/42811962/9409337

Espera Awo Over a year ago

Yes it's not a good design pattern. Those requests should be in your repository then sent to your viewModel. Your viewModel observe your repo

Collectives™ on Stack Overflow

Firebase doesn't load data at first time

1 Answer 1

3 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related