Callback

abstract class Callback
kotlin.Any
   ↳ androidx.sqlite.db.SupportSQLiteOpenHelper.Callback

Handles various lifecycle events for the SQLite connection, similar to android.database.sqlite.SQLiteOpenHelper.

Summary

Public constructors
<init>(version: Int)

Creates a new Callback to get database lifecycle events.

Public methods
open Unit
onDowngrade(db: SupportSQLiteDatabase!, oldVersion: Int, newVersion: Int)

Called when the database needs to be downgraded.

abstract Unit

Called when the database is created for the first time.

open Unit

Called when the database has been opened.

open Unit

Called when the database connection is being configured, to enable features such as write-ahead logging or foreign key support.

open Unit

The method invoked when database corruption is detected.

abstract Unit
onUpgrade(db: SupportSQLiteDatabase!, oldVersion: Int, newVersion: Int)

Called when the database needs to be upgraded.

Properties
Int

Version number of the database (starting at 1); if the database is older, SupportSQLiteOpenHelper.Callback#onUpgrade(SupportSQLiteDatabase, int, int) will be used to upgrade the database; if the database is newer, SupportSQLiteOpenHelper.Callback#onDowngrade(SupportSQLiteDatabase, int, int) will be used to downgrade the database.

Public constructors

<init>

Callback(version: Int)

Creates a new Callback to get database lifecycle events.

Parameters
version Int: The version for the database instance. See version.

Public methods

onDowngrade

open fun onDowngrade(db: SupportSQLiteDatabase!, oldVersion: Int, newVersion: Int): Unit

Called when the database needs to be downgraded. This is strictly similar to onUpgrade method, but is called whenever current version is newer than requested one. However, this method is not abstract, so it is not mandatory for a customer to implement it. If not overridden, default implementation will reject downgrade and throws SQLiteException

This method executes within a transaction. If an exception is thrown, all changes will automatically be rolled back.

Parameters
db SupportSQLiteDatabase!: The database.
oldVersion SupportSQLiteDatabase!: The old database version.
newVersion SupportSQLiteDatabase!: The new database version.

onCreate

abstract fun onCreate(db: SupportSQLiteDatabase!): Unit

Called when the database is created for the first time. This is where the creation of tables and the initial population of the tables should happen.

Parameters
db SupportSQLiteDatabase!: The database.

onOpen

open fun onOpen(db: SupportSQLiteDatabase!): Unit

Called when the database has been opened. The implementation should check SupportSQLiteDatabase#isReadOnly before updating the database.

This method is called after the database connection has been configured and after the database schema has been created, upgraded or downgraded as necessary. If the database connection must be configured in some way before the schema is created, upgraded, or downgraded, do it in onConfigure instead.

Parameters
db SupportSQLiteDatabase!: The database.

onConfigure

open fun onConfigure(db: SupportSQLiteDatabase!): Unit

Called when the database connection is being configured, to enable features such as write-ahead logging or foreign key support.

This method is called before onCreate, onUpgrade, onDowngrade, or onOpen are called. It should not modify the database except to configure the database connection as required.

This method should only call methods that configure the parameters of the database connection, such as SupportSQLiteDatabase#enableWriteAheadLogging SupportSQLiteDatabase#setForeignKeyConstraintsEnabled, SupportSQLiteDatabase#setLocale, SupportSQLiteDatabase#setMaximumSize, or executing PRAGMA statements.

Parameters
db SupportSQLiteDatabase!: The database.

onCorruption

open fun onCorruption(db: SupportSQLiteDatabase!): Unit

The method invoked when database corruption is detected. Default implementation will delete the database file.

Parameters
db SupportSQLiteDatabase!: the SupportSQLiteDatabase object representing the database on which corruption is detected.

onUpgrade

abstract fun onUpgrade(db: SupportSQLiteDatabase!, oldVersion: Int, newVersion: Int): Unit

Called when the database needs to be upgraded. The implementation should use this method to drop tables, add tables, or do anything else it needs to upgrade to the new schema version.

The SQLite ALTER TABLE documentation can be found here. If you add new columns you can use ALTER TABLE to insert them into a live table. If you rename or remove columns you can use ALTER TABLE to rename the old table, then create the new table and then populate the new table with the contents of the old table.

This method executes within a transaction. If an exception is thrown, all changes will automatically be rolled back.

Parameters
db SupportSQLiteDatabase!: The database.
oldVersion SupportSQLiteDatabase!: The old database version.
newVersion SupportSQLiteDatabase!: The new database version.

Properties

version

val version: Int

Version number of the database (starting at 1); if the database is older, SupportSQLiteOpenHelper.Callback#onUpgrade(SupportSQLiteDatabase, int, int) will be used to upgrade the database; if the database is newer, SupportSQLiteOpenHelper.Callback#onDowngrade(SupportSQLiteDatabase, int, int) will be used to downgrade the database.