How do I completely recreate my database in Android Room?

Question

I have a situation where I want to be able to do a hard reset of my database using Android Room. Using SQLiteOpenHelper, I could do this by writing a method to drop all tables and indices, then manually call SQLiteOpenHelper.onCreate().

I'm aware that I can get access to a SupportSQLiteOpenHelper via room and drop all the tables myself, but there doesn't seem to be a good way to kick-off the recreation process.

Also, I'm aware that I could delete every item from each table without dropping it, but that's not what I want. That doesn't reset the auto-incrementing primary key, so the "id" field of new items won't reset back to 1.

Thanks!

EDIT:
This is something I want to be able to do arbitrarily at runtime.

EDIT 2:
The method should be maintainable, i.e. not involve hand-writing SQL that matches Room's behavior. Ideally there would be some way to retrieve the SQL that Room generates, or a SQLiteOpenHelper.onCreate() equivalent method. Or anything else that solves this problem! :)

Answer 1

I found it easiest to do this via context.deleteDatabase(“name”) and then simply reinstantiating and repopulating the database via the Room.databaseBuilder().addCallback upon first access.

Answer 2

Simple answer is to increment your @Database version number. Generally speaking you should do this for schema changes, however it will achieve your aims of clearing the database and resetting all primary key values.

@Database(entities = { Hello.class }}, version = 1) // <- you want to increase version by 1 @TypeConverters({}) public abstract class AppDatabase extends RoomDatabase {     public abstract HelloDao helloTextDao(); } 

EDIT: IF you want to do this at run time, I would clear all the data from your tables (to avoid FK issues), then call DROP TABLE table_name, on all of your respective tables. Then you will need to write queries for creating the tables ie : CREATE TABLE table_name (uid INTEGER PRIMARY KEY, name STRING);.

This will mean you have to maintain a list of create table queries up to date with your POJO's unfortunatly. Ideally you'd be able to use reflection to generate the query, howerever @ColumnInfo currently doesn't support reflection as it has its RetentionPolicy set to CLASS.

Hopefully this solves your problem, feel free to ask for further clarification in the comments. Happy hunting!