107 lines
3.9 KiB
Kotlin
107 lines
3.9 KiB
Kotlin
package com.h.pixeldroid.fragments.feeds.cachedFeeds
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import android.os.Bundle
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import android.view.LayoutInflater
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import android.view.View
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import android.view.ViewGroup
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import androidx.lifecycle.ViewModel
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import androidx.lifecycle.ViewModelProvider
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import androidx.lifecycle.lifecycleScope
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import androidx.paging.*
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import androidx.recyclerview.widget.RecyclerView
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import kotlinx.coroutines.Job
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import kotlinx.coroutines.flow.collect
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import kotlinx.coroutines.flow.collectLatest
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import kotlinx.coroutines.flow.distinctUntilChangedBy
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import kotlinx.coroutines.flow.filter
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import kotlinx.coroutines.launch
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import com.h.pixeldroid.databinding.FragmentFeedBinding
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import com.h.pixeldroid.db.AppDatabase
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import com.h.pixeldroid.db.dao.feedContent.FeedContentDao
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import com.h.pixeldroid.fragments.BaseFragment
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import com.h.pixeldroid.fragments.feeds.initAdapter
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import com.h.pixeldroid.objects.FeedContentDatabase
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/**
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* A fragment representing a list of [FeedContentDatabase] items that are cached by the database.
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*/
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open class CachedFeedFragment<T: FeedContentDatabase> : BaseFragment() {
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internal lateinit var viewModel: FeedViewModel<T>
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internal lateinit var adapter: PagingDataAdapter<T, RecyclerView.ViewHolder>
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private lateinit var binding: FragmentFeedBinding
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private var job: Job? = null
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internal fun launch() {
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// Make sure we cancel the previous job before creating a new one
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job?.cancel()
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job = lifecycleScope.launch {
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viewModel.flow().collectLatest {
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adapter.submitData(it)
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}
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}
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}
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internal fun initSearch() {
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// Scroll to top when the list is refreshed from network.
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lifecycleScope.launch {
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adapter.loadStateFlow
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// Only emit when REFRESH LoadState for RemoteMediator changes.
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.distinctUntilChangedBy { it.refresh }
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// Only react to cases where Remote REFRESH completes i.e., NotLoading.
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.filter { it.refresh is LoadState.NotLoading }
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.collect { binding.list.scrollToPosition(0) }
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}
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}
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override fun onCreateView(
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inflater: LayoutInflater, container: ViewGroup?,
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savedInstanceState: Bundle?
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): View? {
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super.onCreateView(inflater, container, savedInstanceState)
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binding = FragmentFeedBinding.inflate(layoutInflater)
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initAdapter(binding, adapter)
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//binding.progressBar.visibility = View.GONE
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binding.swipeRefreshLayout.setOnRefreshListener {
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//It shouldn't be necessary to also retry() in addition to refresh(),
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//but if we don't do this, reloads after an error fail immediately...
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// https://issuetracker.google.com/issues/173438474
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adapter.retry()
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adapter.refresh()
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}
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return binding.root
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}
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}
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/**
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* Factory that creates ViewModel from a [FeedContentRepository], to be used in cached feeds to
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* fetch the ViewModel that is responsible for preparing and managing the data for
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* an Activity or a Fragment
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*/
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class ViewModelFactory<U: FeedContentDatabase> @ExperimentalPagingApi constructor(private val db: AppDatabase?,
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private val dao: FeedContentDao<U>?,
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private val remoteMediator: RemoteMediator<Int, U>?,
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private val feedContentRepository: FeedContentRepository<U> = FeedContentRepository(db!!, dao!!, remoteMediator!!)
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) : ViewModelProvider.Factory {
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@ExperimentalPagingApi
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override fun <T : ViewModel> create(modelClass: Class<T>): T {
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if (modelClass.isAssignableFrom(FeedViewModel::class.java)) {
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@Suppress("UNCHECKED_CAST")
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return FeedViewModel(feedContentRepository) as T
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}
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throw IllegalArgumentException("Unknown ViewModel class")
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}
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} |