Room persistance library. Delete all

How can I delete all entries on specific table using Room Persistence Library? I need to drop table, but I cannot to find any information how to do this.

Only when database is migrating or to load all entries and delete them :)

Solution 1:

You can create a DAO method to do this.

@Dao 
interface MyDao {
    @Query("DELETE FROM myTableName")
    public void nukeTable();
}

Solution 2:

As of Room 1.1.0 you can use clearAllTables() which:

Deletes all rows from all the tables that are registered to this database as entities().

Solution 3:

If want to delete an entry from the the table in Room simply call this function,

@Dao
public interface myDao{
    @Delete
    void delete(MyModel model);
}

Update: And if you want to delete complete table, call below function,

  @Query("DELETE FROM MyModel")
  void delete();

Note: Here MyModel is a Table Name.

Solution 4:

Use clearAllTables() with RXJava like below inorder to avoid java.lang.IllegalStateException: Cannot access database on the main thread since it may potentially lock the UI for a long period of time.

Completable.fromAction(new Action() {
        @Override
        public void run() throws Exception {
            getRoomDatabase().clearAllTables();
        }
    }).subscribeOn(getSchedulerProvider().io())
            .observeOn(getSchedulerProvider().ui())
            .subscribe(new Action() {
                @Override
                public void run() throws Exception {
                    Log.d(TAG, "--- clearAllTables(): run() ---");
                    getInteractor().setUserAsLoggedOut();
                    getMvpView().openLoginActivity();
                }
            }, new Consumer<Throwable>() {
                @Override
                public void accept(Throwable throwable) throws Exception {
                    Log.d(TAG, "--- clearAllTables(): accept(Throwable throwable) ----");
                    Log.d(TAG, "throwable.getMessage(): "+throwable.getMessage());


                }
            });