I tried to implement custom TiledDataSource for using with paging library. When I used LivePagedListProvider like returns type for my Dao method it worked fine (after table items updating - ui updated automatically).
@Query("SELECT * FROM " + Table.States.PLAY_STATE + ", "+Table.Chart.ARTIST+ " ORDER BY position ASC")
LivePagedListProvider<Artist> loadArtists();
But when I try implement custom TiledDataSource for LivePagerListProvider table updates not triggered my observers.
Abstract generic class:
public abstract class PagedNetworkBoundResource<ResultType, RequestType> extends TiledDataSource<ResultType> {
@Override
public int countItems() {
return DataSource.COUNT_UNDEFINED;
}
@Override
public List<ResultType> loadRange(int startPosition, int count) {
fetchFromNetwork(startPosition, count);
return loadFromDb(startPosition, count);
}
@WorkerThread
private void fetchFromNetwork(int startPosition, int count) {
if (createCall(startPosition, count) != null)
try {
Response<RequestType> response = createCall(startPosition, count).execute();
if (response.isSuccessful() && response.code() == 200) {
saveCallResult(response.body());
}
} catch (IOException e) {
e.printStackTrace();
}
}
@WorkerThread
protected abstract void saveCallResult(@NonNull RequestType item);
@WorkerThread
protected abstract List<ResultType> loadFromDb(int startPosition, int count);
@WorkerThread
protected abstract Call<RequestType> createCall(int startPosition, int count);
public LiveData<PagedList<ResultType>> getAsLiveData() {
return new LivePagedListProvider<Integer, ResultType>() {
@Override
protected DataSource<Integer, ResultType> createDataSource() {
return PagedNetworkBoundResource.this;
}
}.create(0, new PagedList.Config.Builder()
.setEnablePlaceholders(false)
.setPageSize(20)
.setInitialLoadSizeHint(20)
.build());
}
}
My dao method for this case:
@Query("SELECT * FROM " + Table.States.PLAY_STATE + ", "+Table.Chart.ARTIST+ " ORDER BY position ASC LIMIT (:limit) OFFSET (:offset)")
List<Artist> loadArtists(int offset, int limit);
I update Table.States.PLAY_STATE.
public void updatePlayerState(PlayerStateEntity state){
new Thread(() -> {
dao.deleteState();
dao.insertState(state);
}).run();
}
@Dao
public interface PlayStateDao {
@Insert(onConflict = OnConflictStrategy.REPLACE)
void insertState(PlayerStateEntity playEntity);
@Query("DELETE FROM " + Table.States.PLAY_STATE)
void deleteState();
@Query("SELECT * FROM "+Table.States.PLAY_STATE)
PlayerStateEntity getPlayerState();
}
@Entity(tableName = Table.States.PLAY_STATE)
public class PlayerStateEntity extends IdEntity {
@ColumnInfo(name = "album_played_id")
private Long albumPlayedId = -1L;
@ColumnInfo(name = "track_played_id")
private Long trackPlayedId = -1L;
@ColumnInfo(name = "artist_played_id")
private Long artistPlayedId = -1L;
@ColumnInfo(name = "state")
private PlayingState state;
@ColumnInfo(name = "playing_type")
private PlayingType playingType;
public Long getAlbumPlayedId() {
return albumPlayedId;
}
public void setAlbumPlayedId(Long albumPlayedId) {
this.albumPlayedId = albumPlayedId;
}
public Long getTrackPlayedId() {
return trackPlayedId;
}
public void setTrackPlayedId(Long trackPlayedId) {
this.trackPlayedId = trackPlayedId;
}
public Long getArtistPlayedId() {
return artistPlayedId;
}
public void setArtistPlayedId(Long artistPlayedId) {
this.artistPlayedId = artistPlayedId;
}
public PlayingState getState() {
return state;
}
public void setState(PlayingState state) {
this.state = state;
}
public PlayingType getPlayingType() {
return playingType;
}
public void setPlayingType(PlayingType playingType) {
this.playingType = playingType;
}
}
class Artist extends PlayEntity{
private String name;
private String link;
private String picture;
@ColumnInfo(name = "picture_small")
private String pictureSmall;
@ColumnInfo(name = "picture_medium")
private String pictureMedium;
@ColumnInfo(name = "picture_big")
private String pictureBig;
@ColumnInfo(name = "picture_xl")
private String pictureXl;
private Boolean radio;
private String tracklist;
private Integer position;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getLink() {
return link;
}
public void setLink(String link) {
this.link = link;
}
public String getPicture() {
return picture;
}
public void setPicture(String picture) {
this.picture = picture;
}
public String getPictureSmall() {
return pictureSmall;
}
public void setPictureSmall(String pictureSmall) {
this.pictureSmall = pictureSmall;
}
public String getPictureMedium() {
return pictureMedium;
}
public void setPictureMedium(String pictureMedium) {
this.pictureMedium = pictureMedium;
}
public String getPictureBig() {
return pictureBig;
}
public void setPictureBig(String pictureBig) {
this.pictureBig = pictureBig;
}
public String getPictureXl() {
return pictureXl;
}
public void setPictureXl(String pictureXl) {
this.pictureXl = pictureXl;
}
public Boolean getRadio() {
return radio;
}
public void setRadio(Boolean radio) {
this.radio = radio;
}
public String getTracklist() {
return tracklist;
}
public void setTracklist(String tracklist) {
this.tracklist = tracklist;
}
public Integer getPosition() {
return position;
}
public void setPosition(Integer position) {
this.position = position;
}
@Override
public boolean isItemPlaying() {
return getId() == getArtistPlayedId().longValue() && getPlayingType() == PlayingType.Artist && getState() == PlayingState.Playing;
}
}
public abstract class PlayEntity extends PlayerStateEntity {
public abstract boolean isItemPlaying();
}
public class ArtistsRepository {
private final ChartArtistDao chartArtistDao;
private final DeezerService deezerService;
@Inject
public ArtistsRepository(ChartArtistDao chartArtistDao, DeezerService deezerService) {
this.chartArtistDao = chartArtistDao;
this.deezerService = deezerService;
}
public LiveData<PagedList<ChartArtistDao.Artist>> getArtist() {
return new PagedNetworkBoundResource<ChartArtistDao.Artist, ModelList<ChartArtistEntity>>() {
@Override
protected void saveCallResult(@NonNull ModelList<ChartArtistEntity> item) {
if (item != null) {
chartArtistDao.saveArtists(item.getItems());
}
}
@Override
protected List<ChartArtistDao.Artist> loadFromDb(int startPosition, int count) {
return chartArtistDao.loadArtists(startPosition, count);
}
@Override
protected Call<ModelList<ChartArtistEntity>> createCall(int startPosition, int count) {
return deezerService.getChartArtist(startPosition, count);
}
}.getAsLiveData();
}
}
For each Artist items I add fields from PlayerStateEntity (not good solution but this easy way to represent state of ui items). After PlayerStateEntity table updates Room should notify about data changes, but doesn't do it.
I understand that Room doesn't know about query what I used, and can't updates my RecyclerView which provide by paging library. But maybe some one knows how to notify Room about tables which I used inside mine DataSource for future triggering ui updates?
