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我有一个包含两个表的数据库。
第一个:queue_incoming
+---------------+
| column_name | pk
+---------------+
|id | 1
|api_id | 0
|driver | 0
|vehicle_number | 0
+---------------+
第二表:包
+------------------+
| column_name | pk
+------------------+
|id | 1
|api_id | 0
|queue_incoming_id | 0
|driver | 0
|vehicle_number | 0
+------------------+
两个表之间的关系是一个queue_incoming有很多包。queue_incoming.id = bag.queue_incoming_id
问题是,我需要将每个queue_incoming记录中的bag的所有记录放到一个List中。
到目前为止,这是代码。非常感谢任何帮助。
实体: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
}
}
存储库
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;
}
}
View 模型: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
我已经声明过了
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
}
最佳答案
我认为您错过了 BagEntity.java 中的 @ForeignKey。 @ForeignKey 将连接两个表,因此如果有任何表更新,将触发实时数据。
第二件事是您的输出列表不是实时数据类型。您必须在 LiveData<List<QueueIncoming>>
等查询中更新输出列表
更新:您可以在您的 viewModel 中尝试这个 //先声明
private final MediatorLiveData<List<QueueIncoming>> mObservableProducts;
在dao调用后的构造函数中
mObservableProducts.addSource(products, new Observer<List<UserEntity>>() {
@Override
public void onChanged(@Nullable List<QueueIncoming> outputDaoList) {
mObservableProducts.postValue(outputDaoList);
}
});
然后在您的 View 模型中编写一个您可以从 Activity 中观察到的方法
public LiveData<List<QueueIncoming>> getAllList() {
return mObservableProducts;
}
关于java - 房间 : LiveData One To Many Relation,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/56539762/
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