TransactionObserver

public protocol TransactionObserver : class

A transaction observer is notified of all changes and transactions committed or rollbacked on a database.

Adopting types must be a class.

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

    Declaration

    Swift

    func observes(eventsOfKind eventKind: DatabaseEventKind) -> Bool
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  • Notifies a database change (insert, update, or delete).

    The change is pending until the end of the current transaction, notified to databaseWillCommit, databaseDidCommit and databaseDidRollback.

    This method is called on the database queue.

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

    Warning

    this method must not change the database.

    Declaration

    Swift

    func databaseDidChange(with event: DatabaseEvent)
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  • 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.

    Warning

    this method must not change the database.

    Throws

    An eventual error that rollbacks pending changes.

    Declaration

    Swift

    func databaseWillCommit() throws
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  • Database changes have been committed.

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

    Declaration

    Swift

    func databaseDidCommit(_ db: Database)
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  • Database changes have been rollbacked.

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

    Declaration

    Swift

    func databaseDidRollback(_ db: Database)
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  • 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 on the database queue.

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

    Warning

    this method must not change the database.

    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 the README.md in /SQLiteCustom/

The databaseDidChangeWithEvent callback is always available,
and may provide most/all of what you need.
(For example, FetchedRecordsController is built without using
this functionality.)