房间数据库 - 插入后如何返回整行？

Question

I have query that inserts a row

@Dao
public interface NoteDao {
    @Insert
    Long insert(Note note);

}

I'm using RxJava to perform the query on the background thread:

 public void insert(Note note) {
        Single.fromCallable(() -> noteDao.insert(note))
                .subscribeOn(Schedulers.newThread())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(new SingleObserver<Long>() {
                    @Override
                    public void onSubscribe(@NonNull Disposable d) {

                    }

                    @Override
                    public void onSuccess(@NonNull Long aLong) {
                        Log.d(TAG, "onSuccess: New row Id: " + aLong);
                    }

                    @Override
                    public void onError(@NonNull Throwable e) {

                    }
                });

    }

Currently it successfully returns, the newly created primary key for the inserted DAO. How would I return the entire inserted row, WITHOUT performing a second query using the new row id?

In postgresql I would do something like this:

`INSERT INTO note_table(note_title, note_description) VALUES ($1, $2) RETURNING *`

Not sure how to do it with the Room library

Answer 1

As stated in the documents of Transcation , if you want to perform two queries in one shot you have to use transactions and there is no other option as far as I know for standard database operations

check below as here we are doing you should do similar

 @Dao
 public interface NoteDao {
    @Insert
    Long insert(Note note);

    @@Query(“SELECT * FROM Note WHERE noteId = :id)
    Long getNote(id Long);

    @Transaction
    public void insertAndRetrieve(Note note):Note {
         // Anything inside this method runs in a single transaction.

         val id =  insert(note);
        return getNote(id);
     }
 }