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Fix RemoteMediator endOfPagination logic #54

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Merged
merged 1 commit into from
Apr 30, 2020
Merged

Fix RemoteMediator endOfPagination logic #54

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18 changes: 8 additions & 10 deletions app/src/main/java/com/example/android/codelabs/paging/data/GithubRemoteMediator.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,6 @@

package com.example.android.codelabs.paging.data

import android.util.Log
import androidx.paging.LoadType
import androidx.paging.PagingState
import androidx.paging.RemoteMediator
Expand Down Expand Up @@ -63,30 +62,29 @@ class GithubRemoteMediator(
val remoteKeys = getRemoteKeyClosestToCurrentPosition(state)
remoteKeys?.nextKey?.minus(1) ?: GITHUB_STARTING_PAGE_INDEX
}
LoadType.START -> {
LoadType.PREPEND -> {
val remoteKeys = getRemoteKeyForFirstItem(state)
if (remoteKeys == null) {
// The LoadType is START so some data was loaded before,
// so we should have been able to get remote keys
// If the remoteKeys are null, then we're an invalid state and we have a bug
throw InvalidObjectException("Remote key and the prevKey should not be null")
}

// If the previous key is null, then we can't request more data
val prevKey = remoteKeys.prevKey
if (prevKey == null) {
return MediatorResult.Success(endOfPaginationReached = false)
}
remoteKeys.prevKey
remoteKeys.prevKey ?: return MediatorResult.Success(endOfPaginationReached = true)
}
LoadType.END -> {
LoadType.APPEND -> {
val remoteKeys = getRemoteKeyForLastItem(state)
if (remoteKeys?.nextKey == null) {
if (remoteKeys == null) {
// The LoadType is END, so some data was loaded before,
// so we should have been able to get remote keys
// If the remoteKeys are null, then we're an invalid state and we have a bug
throw InvalidObjectException("Remote key should not be null for $loadType")
}
remoteKeys.nextKey

// If the next key is null, then we can't request more data
remoteKeys.nextKey ?: return MediatorResult.Success(endOfPaginationReached = true)
}
}

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2 changes: 1 addition & 1 deletion build.gradle
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Original file line number Diff line number Diff line change
Expand Up @@ -35,7 +35,7 @@ allprojects {
repositories {
google()
jcenter()
maven { url 'https://androidx-dev-prod.appspot.com/snapshots/builds/6433189/artifacts/repository' }
maven { url 'https://androidx-dev-prod.appspot.com/snapshots/builds/6445242/artifacts/repository' }
}
}

Expand Down