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Using activeSurveyFlow to make flow async #2890

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Using activeSurveyFlow to make flow async #2890

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cf67dce
using activeSurveyFlow
anandwana001 Dec 1, 2024
222adf4
Merge branch 'master' into anandwana001/2815/use-active-survey-flow
gino-m Dec 3, 2024
8bac153
Merge branch 'master' into anandwana001/2815/use-active-survey-flow
anandwana001 Dec 5, 2024
480564d
Merge branch 'master' into anandwana001/2815/use-active-survey-flow
anandwana001 Dec 11, 2024
392861a
Merge branch 'master' into anandwana001/2815/use-active-survey-flow
anandwana001 Dec 12, 2024
c351daa
suggested fix
anandwana001 Dec 17, 2024
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8 changes: 7 additions & 1 deletion ground/src/main/java/com/google/android/ground/ui/datacollection/DataCollectionViewModel.kt
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Expand Up @@ -61,10 +61,13 @@ import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.SharingStarted
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.asStateFlow
import kotlinx.coroutines.flow.filterNotNull
import kotlinx.coroutines.flow.first
import kotlinx.coroutines.flow.firstOrNull
import kotlinx.coroutines.flow.flow
import kotlinx.coroutines.flow.stateIn
import kotlinx.coroutines.launch
import kotlinx.coroutines.runBlocking
import timber.log.Timber

/** View model for the Data Collection fragment. */
Expand Down Expand Up @@ -97,7 +100,10 @@ internal constructor(
private var shouldLoadFromDraft: Boolean = savedStateHandle[TASK_SHOULD_LOAD_FROM_DRAFT] ?: false
private var draftDeltas: List<ValueDelta>? = null

private val activeSurvey: Survey = requireNotNull(surveyRepository.activeSurvey)
private val activeSurvey: Survey = runBlocking {
surveyRepository.activeSurveyFlow.filterNotNull().first()
}
Comment on lines +103 to +105
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What will happen if the coroutine is never completed? Will the app freeze until ANR error occurs?

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During the standup today, @anandwana001 suggested adding a timeout here. @gino-m I suggested that we allow the timeout exception to propagate and crash the app, since not being able to load the survey from the local db would be an unrecoverable error.

Ideally, we would ensure the survey was active before rendering the DataCollectionFragment. We could then use SurveyRepository.activeSurvey directly rather than the Flow to get the current survey. @shobhitagarwal1612 Is this possible, based on how the fragment gets activated?

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Ideally, we would ensure the survey was active before rendering the DataCollectionFragment. We could then use SurveyRepository.activeSurvey directly rather than the Flow to get the current survey. @shobhitagarwal1612 Is this possible, based on how the fragment gets activated?

I don't think so, the fragment gets restored when the activity is started and the injected dependencies are initialized after the fragment is created.

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I don't think so, the fragment gets restored when the activity is started and the injected dependencies are initialized after the fragment is created.

On configuration change, yes, but on app restart we explicitly redirect to this fragment if there's an unsaved draft, no? On configuration change the VM should still exist, so this wouldn't be an issue. In HomeScreenFragment.onViewCreated, however, we navigate to the data collection screen if there's an unsaved draft.

That said, I agree it would be more robust for the fragment which needs the survey to handle the edge cases, rather than the navigation source.

@anandwana001 Let's keep the fix in this PR plus timeout as a workaround, we can add other handle delayed load and other edge cases if it turns out to be an issue.


private val job: Job = activeSurvey.getJob(jobId) ?: error("couldn't retrieve job for $jobId")
private var customLoiName: String?
get() = savedStateHandle[TASK_LOI_NAME_KEY]
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