房间：LiveData 一对多关系

Question

I have a database with two tables in it.

1st: queue_incoming

+---------------+
|  column_name  | pk   
+---------------+
|id             | 1
|api_id         | 0
|driver         | 0
|vehicle_number | 0
+---------------+

2nd table: bag

+------------------+
|  column_name     | pk   
+------------------+
|id                | 1
|api_id            | 0
|queue_incoming_id | 0
|driver            | 0
|vehicle_number    | 0
+------------------+

The relation between the two tables is that one queue_incoming has many bags. queue_incoming.id = bag.queue_incoming_id

The problem is, I need all the records of bag in each queue_incoming record into one List.

So far, this is the code. Any help it so appreciated.

Entity : QueueIncomingEntity.java

@Entity(tableName = "queue_incoming")
public class QueueIncomingEntity {

    @PrimaryKey(autoGenerate = true)
    private Long id;

    @ColumnInfo(name = "api_id")
    private Integer ApiId;

    @ColumnInfo(name = "driver")
    private String driver;

    @ColumnInfo(name = "vehicle_number")
    private String vehicleNumber;

    @ColumnInfo(name = "date_unique_number")
    private String dateUniqueNumber;

    @ColumnInfo(name = "unique_number")
    private String uniqueNumber;

    @ColumnInfo(name = "message")
    private String message;

    @ColumnInfo(name = "status")
    private String status;

    @Ignore
    private List<BagEntity> bagEntities; // handle all bags in each queue

    // Constructor
    public QueueIncomingEntity(String driver, String vehicleNumber, String dateUniqueNumber, String uniqueNumber, String message, String status) {
        this.driver = driver;
        this.vehicleNumber = vehicleNumber;
        this.dateUniqueNumber = dateUniqueNumber;
        this.uniqueNumber = uniqueNumber;
        this.message = message;
        this.status = status;
    }

    // Getter Setter

}

DAO : QueueIncomingDao.java

@Dao
public interface QueueIncomingDao {

    @Insert(onConflict = OnConflictStrategy.REPLACE)
    long insert(QueueIncomingEntity queueIncomingEntity);

    @Update
    void update(QueueIncomingEntity queueIncomingEntity);

    @Delete
    void delete(QueueIncomingEntity queueIncomingEntity);

    @Query("DELETE FROM queue_incoming")
    void deleteAll();

    @Query("SELECT * FROM queue_incoming WHERE id =:id")
    QueueIncomingEntity findById(long id);

    @Query("SELECT * FROM queue_incoming ORDER BY id DESC")
    LiveData<List<QueueIncomingEntity>> getAll();

    // This is the problem, how to pass this , or how to related this on LiveData
    @Query("SELECT " +
            "bag.id as id," +
            "bag.api_id as apiId," +
            "bag.bag_number as bagNumber," +
            "bag.lot_number as lotNumber," +
            "bag.consignee_name as consigneeName," +
            "bag.allocation_consignee as allocationConsignee," +
            "bag.nett_weight as nettWeight," +
            "bag.gross_weight as grossWeight " +
            "FROM queue_incoming " +
            "LEFT JOIN bag bag ON bag.queue_incoming_id = queue_incoming.id WHERE queue_incoming.id = :id")
    List<QueueIncoming> getAllJoinBags(long id);

    // Inner class to handle method getAllJoinBags
    class QueueIncoming {
        public Long id;
        public Integer apiId;
        public Integer bagNumber;
        public String lotNumber;
        public String consigneeName;
        public String allocationConsignee;
        public Integer nettWeight;
        public Integer grossWeight;

        // Getter Setter
    }

}

Repository

public class QueueIncomingRepository {

    private QueueIncomingDao queueIncomingDao;
    private BagDao bagDao;
    private Context context;
    private ArrayList<BagLotNumberModel> bagLotNumbers;
    private LiveData<List<QueueIncomingEntity>> listLiveData;

    // constructor
    public QueueIncomingRepository(Application application) {

        AppDatabase database = AppDatabase.getInstance(application);

        queueIncomingDao = database.queueIncomingDao();
        listLiveData = queueIncomingDao.getAll();
    }

     // a lot of crud code

     // Handling LiveData
    public LiveData<List<QueueIncomingEntity>> getAll() {
        return listLiveData;
    }
}

ViewModel : QueueIncomingViewModel.java

public class QueueIncomingViewModel extends AndroidViewModel {

    private QueueIncomingRepository queueIncomingRepository;
    private LiveData<List<QueueIncomingEntity>> listLiveData;

    /**
     * Create constructor matching super
     */
    public QueueIncomingViewModel(@NonNull Application application) {
        super(application);
        queueIncomingRepository = new QueueIncomingRepository(application);
        listLiveData = queueIncomingRepository.getAll();
    }

    public void insert(QueueIncomingEntity queueIncomingEntity) {
        queueIncomingRepository.insert(queueIncomingEntity);
    }

    public void update(QueueIncomingEntity queueIncomingEntity) {
        queueIncomingRepository.update(queueIncomingEntity);
    }

    public void delete(QueueIncomingEntity queueIncomingEntity) {
        queueIncomingRepository.delete(queueIncomingEntity);
    }

    public void deleteAll() {
        queueIncomingRepository.deleteAll();
    }

    public LiveData<List<QueueIncomingEntity>> getListLiveData() {
        return listLiveData;
    }
}

Activity : AntamQueueIncomingRoomActivity.java

public class AntamQueueIncomingRoomActivity extends AppCompatActivity {

    public static final int ADD_QUEUE_INCOMING = 1;
    public static final int EDIT_QUEUE_INCOMING = 2;
    public static final int EDIT_QUEUE_INCOMING_BAGS = 3;
    public static final int RE_UPLOAD = 4;

    private QueueIncomingViewModel queueIncomingViewModel;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_antam_incoming_room);

        RecyclerView recyclerView = findViewById(R.id.recycler_view_antam_queue_incoming);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setHasFixedSize(true);

        QueueIncomingAdapter adapter = new QueueIncomingAdapter();
        recyclerView.setAdapter(adapter);

        queueIncomingViewModel = ViewModelProviders.of(this).get(QueueIncomingViewModel.class);
        queueIncomingViewModel.getListLiveData().observe(this, queueIncomingEntities -> {

            adapter.submitList(queueIncomingEntities);

        });

        FloatingActionButton fab = findViewById(R.id.fab);
        fab.setOnClickListener(view -> {
            Intent intent = new Intent(getApplicationContext(), AntamAddEditQueueIncomingRoomActivity.class);
            startActivityForResult(intent, ADD_QUEUE_INCOMING);
        });

        //handling item click on row adapter
        adapter.setOnItemClickListener(new QueueIncomingAdapter.OnItemClickListener() {
            @Override
            public void onItemClick(QueueIncomingEntity queueIncomingEntity) {

                String[] options = {"1. Update Master Incoming", "2. Update Detail Bags", "3. Re-Upload"};
                AlertDialog.Builder builder = new AlertDialog.Builder(AntamQueueIncomingRoomActivity.this);
                builder.setTitle("Menu: " + queueIncomingEntity.getDriver() + " # " + queueIncomingEntity.getVehicleNumber());
                builder.setItems(options, (dialog, which) -> {
                    switch (which) {
                        case 2:
                            Intent intent2 = new Intent(AntamQueueIncomingRoomActivity.this, AntamDialogReUploadIncomingActivity.class);

                            // Data Master
                            intent2.putExtra(AntamDialogReUploadIncomingActivity.EXTRA_ID, Long.valueOf(queueIncomingEntity.getId()));
                            intent2.putExtra(AntamDialogReUploadIncomingActivity.EXTRA_API_ID, queueIncomingEntity.getApiId());

                            // Get Data Detail bags, how ?
                            // Get and passing All bags into new ActivityForResult

                            startActivityForResult(intent2, RE_UPLOAD);
                            break;
                        default:
                            break;
                    }
                });
                builder.show();
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (requestCode == ADD_QUEUE_INCOMING && resultCode == RESULT_OK) {

            // insert


        } else if (requestCode == EDIT_QUEUE_INCOMING && resultCode == RESULT_OK) {

            Long id = Long.valueOf(data.getLongExtra(AntamAddEditQueueIncomingRoomActivity.EXTRA_ID, -1));

            // Update
            queueIncomingEntity.setId(id);
            queueIncomingViewModel.update(queueIncomingEntity);

            Toast.makeText(this, data.getStringExtra(AntamAddEditQueueIncomingRoomActivity.EXTRA_DRIVER) + " is successfully updated", Toast.LENGTH_SHORT).show();
        } else if (requestCode == RE_UPLOAD) {

        }
    }
}

BagEntity.java

I already declare it before

import android.arch.persistence.room.ColumnInfo;
import android.arch.persistence.room.Entity;
import android.arch.persistence.room.ForeignKey;
import android.arch.persistence.room.PrimaryKey;

@Entity(
        tableName = "bag",
        foreignKeys = {
                @ForeignKey(
                        entity = QueueIncomingEntity.class,
                        parentColumns = "id",
                        childColumns = "queue_incoming_id",
                        onDelete = ForeignKey.CASCADE
                ),

                @ForeignKey(
                        entity = QueueContainerStuffingEntity.class,
                        parentColumns = "id",
                        childColumns = "queue_container_stuffing_id"
                )
        }
)
public class BagEntity {

    @PrimaryKey(autoGenerate = true)
    private Long id;

    @ColumnInfo(name = "api_id")
    private Long ApiId;

    @ColumnInfo(name = "queue_incoming_id", index = true)
    private Long queueIncomingId;

    @ColumnInfo(name = "queue_container_stuffing_id", index = true)
    private Long queueContainerStuffingId;

    @ColumnInfo(name = "bag_number")
    private Integer bagNumber;

    @ColumnInfo(name = "lot_number")
    private String lotNumber;

    @ColumnInfo(name = "consignee_name")
    private String consigneeName;

    @ColumnInfo(name = "allocation_consignee")
    private String allocationConsignee;

    @ColumnInfo(name = "nett_weight")
    private Integer nettWeight;

    @ColumnInfo(name = "gross_weight")
    private Integer grossWeight;


    public BagEntity(Long ApiId, Integer bagNumber, String lotNumber, String consigneeName, String allocationConsignee, Integer nettWeight, Integer grossWeight, Long queueIncomingId, Long queueContainerStuffingId) {
        this.ApiId = ApiId;
        this.bagNumber = bagNumber;
        this.lotNumber = lotNumber;
        this.consigneeName = consigneeName;
        this.allocationConsignee = allocationConsignee;
        this.nettWeight = nettWeight;
        this.grossWeight = grossWeight;
        this.queueIncomingId = queueIncomingId;
        this.queueContainerStuffingId = queueContainerStuffingId;
    }

    // Getter Setter


}

Answer 1

I think you miss the @ForeignKey in your BagEntity.java. @ForeignKey will connect two table so if any table update live data will be triggered.

And Second things is that your output list is not Live data type. You have to update your output list in query like LiveData<List<QueueIncoming>>

Update : You can try this in your viewModel //first declare

private final MediatorLiveData<List<QueueIncoming>> mObservableProducts;

In constructor after dao call

mObservableProducts.addSource(products, new Observer<List<UserEntity>>() {
            @Override
            public void onChanged(@Nullable List<QueueIncoming> outputDaoList) {
                mObservableProducts.postValue(outputDaoList);
            }
        });

And write a method in your viewmodel that you can observe from activity

public LiveData<List<QueueIncoming>> getAllList() {
        return mObservableProducts;
    }