Room persistance library Delete all

Question

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

User · Answer

I had issues with delete all method when using RxJava to execute this task on background. This is how I finally solved it:

@Dao
interface UserDao {
    @Query("DELETE FROM User")
    fun deleteAll()
}

and

fun deleteAllUsers() {
    return Maybe.fromAction(userDao::deleteAll)
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe ({
            d("database rows cleared: $it")
        }, {
            e(it)
        }).addTo(compositeDisposable)
}

User · Answer

You can create a DAO method to do this    Dao  interface MyDao        Query  DELETE FROM myTableName       public void nukeTable

User · Answer

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

User · Answer

Here is how I have done it in Kotlin   Inject room db in the activity using DI  Koin    private val appDB  AppDB by inject     Then you can simply call clearAllTables     private fun clearRoomDB         GlobalScope launch           appDB clearAllTables           preferences put PreferenceConstants IS UPLOADCATEGORIES SAVED TO DB  false          preferences put PreferenceConstants IS MEMBERHANDBOOK SAVED TO DB  false

User · Answer

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

User · Answer

Combining what Dick Lucas says and adding a reset autoincremental from other StackOverFlow posts  i think this can work  fun clearAndResetAllTables    Boolean       val db   db    return false         reset all auto-incrementalValues     val query   SimpleSQLiteQuery  quot DELETE FROM sqlite sequence quot        db beginTransaction       return try           db clearAllTables           db query query          db setTransactionSuccessful           true       catch  e  Exception           false       finally           db endTransaction

User · Answer

To make use of the Room without abuse of the  Query annotation first use  Query to select all rows and put them in a list  for example    Query  SELECT   FROM your class table    List  lt  your class  gt   load all your class      Put his list into the delete annotation  for example     Delete  void deleteAllOfYourTable List  lt  your class  gt   your class list

User · Answer

This is how we do it  fun Fragment emptyDatabase         viewLifecycleOwner lifecycleScope launchWhenCreated           withContext Dispatchers IO                Database getInstance requireActivity    clearAllTables

User · Answer

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 lt Throwable gt                       Override                 public void accept Throwable throwable  throws Exception                       Log d TAG   --- clearAllTables    accept Throwable throwable  ----                        Log d TAG   throwable getMessage      throwable getMessage

[android] Room persistance library. Delete all

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