Scenario
Hi, I have an Activity with a ViewPager. In the ViewPagerAdapter, I create instances of a same fragment with different data. And in each instance I initialize a ViewModel
val dataViewModelFactory = this.activity?.let { DataViewModelFactory(it) }
mainViewModel = ViewModelProviders.of(this, dataViewModelFactory).get(MainViewModel::class.java)
In my fragment, I observe two MutableLiveData when I call APIs
mainViewModel.isResponseSuccessful.observe(this, Observer { it ->
if(it) {
//do Something
}else{
Toast.makeText(activity, "Error in Sending Request", Toast.LENGTH_SHORT).show()
}
})
mainViewModel.isLoading.observe(this, Observer {
if (it) {
println("show progress")
} else {
println("dismiss progress")
}
})
In each fragment, on a button click I load another fragment. And if required call and API to fetch data.
PROBLEM
The code comes to the observe block multiple times in my fragment. When I comeback from one fragment to previous fragment, even though no API is called, the code on observe block is executed.
What I tried
I tried using an activity instance in the ViewModel initialization
mainViewModel = ViewModelProviders.of(activity,dataViewModelFactory).get(MainViewModel::class.java)
But it did not work.
Please help,
If you want to prevent multiple calls of your observer u can just change MutableLiveData
to SingleLiveEvent
. Read this