Android Room-获取新插入行表单@Insert的id
在下面的代码中,我得到了Android Room-获取新插入行表单@Insert的id,android,database,android-room,Android,Database,Android Room,在下面的代码中,我得到了rowId。我已经了解到,还可以直接从@Insert获取最后插入的行id。在我的代码中,我将void insert改为long,并尝试了许多其他方法,就像我在互联网上找到的示例一样,但每次我都会出错。是否要为我提供代码/解决方案以从@Insert获取行/用户ID @Dao public interface UserDao { @Insert void insert(UserEntity userEntity); @Update void
rowId
。我已经了解到,还可以直接从@Insert
获取最后插入的行id。在我的代码中,我将void insert改为long,并尝试了许多其他方法,就像我在互联网上找到的示例一样,但每次我都会出错。是否要为我提供代码/解决方案以从@Insert获取行/用户ID
@Dao
public interface UserDao {
@Insert
void insert(UserEntity userEntity);
@Update
void update(UserEntity userEntity);
@Delete
void delete(UserEntity userEntity);
@Query("DELETE FROM user_table")
void deleteAllUsers();
@Query("SELECT * FROM user_table")
LiveData<List<UserEntity>> getAllUsers();
// ====== from here ======
@Query("SELECT * FROM user_table")
LiveData<UserEntity> getRowId();
// ====== till here ======
}
存储库
public class UserRepository {
private UserDao userDao;
private LiveData<List<UserEntity>> allUsers;
public UserRepository(Application application) {
HandymanDatabase handymanDatabase = HandymanDatabase.getInstance(application);
userDao = handymanDatabase.userDao();
allUsers = userDao.getAllUsers();
}
public void insert(UserEntity userEntity) {
new InsertUserAsyncTask(userDao).execute(userEntity);
}
public void update(UserEntity userEntity) {
new UpdateUserAsyncTask(userDao).execute(userEntity);
}
public void delete(UserEntity userEntity) {
new DeleteUserAsyncTask(userDao).execute(userEntity);
}
public void deleteAllUsers() {
new DeleteAllUsersAsyncTask(userDao).execute();
}
public LiveData<List<UserEntity>> getAllUsers() {
return allUsers;
}
// ====== from here ======
public LiveData<UserEntity> getRowId() {
return userDao.getRowId();
}
// ====== till here ======
private static class InsertUserAsyncTask extends AsyncTask<UserEntity, Void, Void> {
private UserDao userDao;
private InsertUserAsyncTask(UserDao userDao) {
this.userDao = userDao;
}
@Override
protected Void doInBackground(UserEntity... userEntities) {
userDao.insert(userEntities[0]);
return null;
}
}
private static class UpdateUserAsyncTask extends AsyncTask<UserEntity, Void, Void> {
private UserDao userDao;
private UpdateUserAsyncTask(UserDao userDao) {
this.userDao = userDao;
}
@Override
protected Void doInBackground(UserEntity... userEntities) {
userDao.update(userEntities[0]);
return null;
}
}
private static class DeleteUserAsyncTask extends AsyncTask<UserEntity, Void, Void> {
private UserDao userDao;
private DeleteUserAsyncTask(UserDao userDao) {
this.userDao = userDao;
}
@Override
protected Void doInBackground(UserEntity... userEntities) {
userDao.delete(userEntities[0]);
return null;
}
}
private static class DeleteAllUsersAsyncTask extends AsyncTask<Void, Void, Void> {
private UserDao userDao;
private DeleteAllUsersAsyncTask(UserDao userDao) {
this.userDao = userDao;
}
@Override
protected Void doInBackground(Void... voids) {
userDao.deleteAllUsers();
return null;
}
}
}
公共类用户存储库{
私有UserDao UserDao;
私有LiveData用户;
公共用户存储库(应用程序){
handymandabase handymandabase=handymandabase.getInstance(应用程序);
userDao=handymandabase.userDao();
allUsers=userDao.getAllUsers();
}
公共作废插入(用户实体用户实体){
新建InsertUserAsyncTask(userDao).execute(userEntity);
}
公共无效更新(用户实体用户实体){
新的UpdateUserSyncTask(userDao).execute(userEntity);
}
公共作废删除(UserEntity UserEntity){
新建DeleteUserAsyncTask(userDao).execute(userEntity);
}
公共图书馆{
新建DeleteAllUsersAsyncTask(userDao).execute();
}
公共LiveData getAllUsers(){
回归诱惑;
}
//======从这里开始======
公共LiveData getRowId(){
返回userDao.getRowId();
}
//直到这里======
私有静态类InsertUserAsyncTask扩展了AsyncTask{
私有UserDao UserDao;
专用InsertUserAsyncTask(UserDao UserDao){
this.userDao=userDao;
}
@凌驾
受保护的Void doInBackground(UserEntity…userEntities){
insert(userEntities[0]);
返回null;
}
}
私有静态类UpdateUserAsyncTask扩展了AsyncTask{
私有UserDao UserDao;
私有UpdateUserAsyncTask(UserDao UserDao){
this.userDao=userDao;
}
@凌驾
受保护的Void doInBackground(UserEntity…userEntities){
update(userEntities[0]);
返回null;
}
}
私有静态类DeleteUserAsyncTask扩展了AsyncTask{
私有UserDao UserDao;
私有DeleteUserAsyncTask(UserDao UserDao){
this.userDao=userDao;
}
@凌驾
受保护的Void doInBackground(UserEntity…userEntities){
userDao.delete(userEntities[0]);
返回null;
}
}
私有静态类deleteAllusAsynctask扩展异步任务{
私有UserDao UserDao;
私有deleteAllusAsynctask(UserDao UserDao){
this.userDao=userDao;
}
@凌驾
受保护的空位背景(空位…空位){
userDao.deleteAllUsers();
返回null;
}
}
}
视图模型
public UserViewModel(@NonNull Application application) {
super(application);
userRepository = new UserRepository(application);
allUsers = userRepository.getAllUsers();
}
public void insert(UserEntity userEntity) {
userRepository.insert(userEntity);
}
public void update(UserEntity userEntity) {
userRepository.update(userEntity);
}
public void delete(UserEntity userEntity) {
userRepository.delete(userEntity);
}
public void deleteAllUsers() {
userRepository.deleteAllUsers();
}
public LiveData<List<UserEntity>> getAllUsers() {
return allUsers;
}
// ====== from here ======
public LiveData<UserEntity> getRowId() {
return userRepository.getRowId();
}
// ====== till here ======
}
public void insertUserEntity(UserEntity entity, NewIdListener listener) {
userRepository.insertUserEntity(entity, listener);
}
public UserViewModel(@NonNull应用程序){
超级(应用);
userRepository=新的userRepository(应用程序);
allUsers=userRepository.getAllUsers();
}
公共作废插入(用户实体用户实体){
userRepository.insert(userEntity);
}
公共无效更新(用户实体用户实体){
userRepository.update(userEntity);
}
公共作废删除(UserEntity UserEntity){
userRepository.delete(userEntity);
}
公共图书馆{
userRepository.deleteAllUsers();
}
公共LiveData getAllUsers(){
回归诱惑;
}
//======从这里开始======
公共LiveData getRowId(){
返回userRepository.getRowId();
}
//直到这里======
}
片段/活动
public class UserFavoritesFragment extends Fragment {
private static final String TAG = "UserFavoritesFragment";
private UserViewModel userViewModel;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = getLayoutInflater().inflate(R.layout.fragment_user_favorites, container, false);
final TextView textViewUserName = view.findViewById(R.id.textViewUserName);
TextView textViewUserPhone = view.findViewById(R.id.textViewUserPhone);
userViewModel = new ViewModelProvider(this).get(UserViewModel.class);
// ====== from here ======
userViewModel.getRowId().observe(getViewLifecycleOwner(), new Observer<UserEntity>() {
@Override
public void onChanged(UserEntity userEntity) {
long rowId = userEntity.getId();
Log.d(TAG, "onChanged: " + rowId);
}
});
// ====== till here ======
return view;
}
}
public类UserFavoritesFragment扩展片段{
私有静态最终字符串TAG=“UserFavoritesFragment”;
私有用户视图模型用户视图模型;
@凌驾
创建时的公共void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
}
@凌驾
创建视图上的公共视图(布局、充气机、视图组容器、,
Bundle savedInstanceState){
视图=GetLayoutFlater()。充气(R.layout.fragment\u user\u收藏夹,容器,false);
最终TextView textViewUserName=view.findViewById(R.id.textViewUserName);
TextView textViewUserPhone=view.findViewById(R.id.textViewUserPhone);
userViewModel=newviewmodelprovider(this.get)(userViewModel.class);
//======从这里开始======
userViewModel.getRowId().observe(getViewLifecycleOwner(),new Observer()){
@凌驾
更改后的公共void(UserEntity UserEntity){
long rowId=userEntity.getId();
Log.d(标记“onChanged:+rowId”);
}
});
//直到这里======
返回视图;
}
}
您可以使用一个侦听器接口来实现这一点,该接口具有一个回调函数,该回调函数接受数据库中插入的行id的长值
侦听器界面
public interface NewIdListener {
void onInsert(long id);
}
Dao
@Dao
public interface UserDao {
@Insert
long insert(UserEntity userEntity); // return id of the inserted userEntity
}
存储库
public class UserRepository {
private Executor mExecutor = Executors.newSingleThreadExecutor();
private UserDao userDao;
...
public void insertUserEntity(final UserEntity entity, final NewIdListener listener) {
mExecutor.execute(new Runnable() {
@Override
public void run() {
listener.onInsert(userDao.insert(entity));
}
});
}
userViewModel.insertUserEntity(new UserEntity("User Name", "12345678"), new NewIdListener() {
@Override
public void onInsert(final long id) {
requireActivity().runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(requireActivity(), "Id: " + id, Toast.LENGTH_SHORT).show();
}
});
}
});
视图模型
public UserViewModel(@NonNull Application application) {
super(application);
userRepository = new UserRepository(application);
allUsers = userRepository.getAllUsers();
}
public void insert(UserEntity userEntity) {
userRepository.insert(userEntity);
}
public void update(UserEntity userEntity) {
userRepository.update(userEntity);
}
public void delete(UserEntity userEntity) {
userRepository.delete(userEntity);
}
public void deleteAllUsers() {
userRepository.deleteAllUsers();
}
public LiveData<List<UserEntity>> getAllUsers() {
return allUsers;
}
// ====== from here ======
public LiveData<UserEntity> getRowId() {
return userRepository.getRowId();
}
// ====== till here ======
}
public void insertUserEntity(UserEntity entity, NewIdListener listener) {
userRepository.insertUserEntity(entity, listener);
}
活动
public class UserRepository {
private Executor mExecutor = Executors.newSingleThreadExecutor();
private UserDao userDao;
...
public void insertUserEntity(final UserEntity entity, final NewIdListener listener) {
mExecutor.execute(new Runnable() {
@Override
public void run() {
listener.onInsert(userDao.insert(entity));
}
});
}
userViewModel.insertUserEntity(new UserEntity("User Name", "12345678"), new NewIdListener() {
@Override
public void onInsert(final long id) {
requireActivity().runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(requireActivity(), "Id: " + id, Toast.LENGTH_SHORT).show();
}
});
}
});
注意:对于后台线程,我使用了
Executor
而不是AsyncTask
,因为AsyncTask
现在已被弃用。感谢您的回复。但我仍然有两个错误。存储库中的一个-变量“listener”是从内部类中访问的,需要声明为final,而活动中的第二个-无法解析符号“entity”。你知道我做错了什么吗?@AJW我在活动中使用匿名侦听器,而不是在ViewModel中,它只是作为方法参数传递给ViewModel,但没有保存在其上;每当上下文被销毁和重新创建并最终重新传递给ViewModel时,该侦听器都将被销毁和重新创建,因此它独立于ViewModel。@Zain Ok我理解。干杯@Zain今晚添加了你的代码