TransactionObserver

Filters database changes that should be notified the the databaseDidChange(with:) method.

Notifies a database change (insert, update, or delete).

The change is pending until the current transaction ends. See databaseWillCommit, databaseDidCommit and databaseDidRollback.

This method is called in a protected dispatch queue, serialized will all database updates.

The event is only valid for the duration of this method call. If you need to keep it longer, store a copy: event.copy()

The observer has an opportunity to stop receiving further change events from the current transaction by calling the stopObservingDatabaseChangesUntilNextTransaction() method.

When a transaction is about to be committed, the transaction observer has an opportunity to rollback pending changes by throwing an error.

This method is called on the database queue.

Database changes have been committed.

This method is called on the database queue. It can change the database.

Database changes have been rollbacked.

This method is called on the database queue. It can change the database.

Notifies before a database change (insert, update, or delete) with change information (initial / final values for the row’s columns). (Called before databaseDidChangeWithEvent.)

The change is pending until the end of the current transaction, and you always get a second chance to get basic event information in the databaseDidChangeWithEvent callback.

This callback is mostly useful for calculating detailed change information for a row, and provides the initial / final values.

This method is called in a protected dispatch queue, serialized will all database updates.

The event is only valid for the duration of this method call. If you need to keep it longer, store a copy: event.copy()

Availability Info

Requires SQLite 3.13.0 + Compiled with option SQLITE_ENABLE_PREUPDATE_HOOK

As of OSX 10.11.5, and iOS 9.3.2, the built-in SQLite library does not have this enabled, so you’ll need to compile your own copy using GRDBCustomSQLite. See https://github.com/groue/GRDB.swift/blob/master/Documentation/CustomSQLiteBuilds.md

The databaseDidChangeWithEvent callback is always available, and may provide most/all of what you need.

After this method has been called, the databaseDidChange(with:) method won’t be called until the next transaction.

For example:

class PlayerObserver: TransactionObserver {
    var playerTableWasModified = false

    func observes(eventsOfKind eventKind: DatabaseEventKind) -> Bool {
        return eventKind.tableName == "player"
    }

    func databaseDidChange(with event: DatabaseEvent) {
        playerTableWasModified = true

        // It is pointless to keep on tracking further changes:
        stopObservingDatabaseChangesUntilNextTransaction()
    }
}