room migration using existing boolean column types

Question

What i found out so far All the @entity annotated classes are processed during compiletime and an Implementation for Database class is generated. Then before accessing the db, validateMigration method of this generated class is called. This validateMigration method verifies with the existing db schema via raw query `PRAGMA table_info mytable name` (see L208 of android.arch.persistence.room.util.TableInfo.java) Now the problem My sqlite3 db has some columns with column type as BOOLEAN. (which slqite internally handles to int). Now when i create room entities say ``` public someEntity { @columnInfo(name="someName") public Boolean myValue; } ``` The room's create table query will be `Create Table someEntity ( myValue INTEGER)` Where as when we query the existing db with `PRAGMA table_info someEntity` we get `1|myValue|BOOLEAN|0||0` As explained above room verifies the ( sqlite to room ) migration by comparing field name, column type etc. And since the column types dont match (BOOLEAN and…

Accepted Answer

Define the migration for the new attribute newAttribute with both a `DEFAULT` value and as `NOT NULL`.

Code

`database.execSQL("ALTER TABLE tableName ADD COLUMN newAttribute INTEGER DEFAULT 0 NOT NULL")`

Full Code

```
@Database(entities = arrayOf(ModelName::class), version = 2)
@TypeConverters(Converters::class)
abstract class DatabaseName : RoomDatabase() {

abstract fun daoName(): DaoName

companion object {

private var INSTANCE: DatabaseName? = null

fun getAppDatabase(context: Context): DatabaseName {
            if (INSTANCE == null) {
                INSTANCE = Room.databaseBuilder(context.applicationContext,
                        DatabaseName::class.java, DATABASE_NAME)
                        .addMigrations(MIGRATION_1_2)
                        .build()
            }
            return INSTANCE as DatabaseName
        }

val MIGRATION_1_2: Migration = object : Migration(1, 2) {
            override fun migrate(database: SupportSQLiteDatabase) {
                database.execSQL("ALTER TABLE tableName ADD COLUMN newAttribute INTEGER DEFAULT 0 NOT NULL")
            }
        }
    }

}
```

room migration using existing boolean column types

Solution

Problem