Changes API

Overview

LokiJS 1.1 introduces a "changes API" that enables the user to keep track of the changes happened to each collection since a particular point in time, which is usually the start of a work session but it could be a user defined one. This is particularly useful for remote synchronization.

Description of the Changes API

The Changes API is a collection-level feature, hence you can establish which collections may simply contain volatile data and which ones need to keep a record of what has changed.

The Changes API is an optional feature and can be activated/deactivated by either passing the option { disableChangesApi: isDisabled } in the config parameter of a collection constructor, or by calling collection.setChangesApi(isEnabled). Note that LokiJS will always set the fastest performing setting as default on a collection or database, hence the Changes API is disabled by default.

There are three events which will trigger a Changes API operation: inserts, updates and deletes. When either of these events occur, on a collection with Changes API activated, the collection will store a snapshot of the relevant object, associated with the operation and the name of the collection.

From the database object is then possible to invoke the serializeChanges method which will generate a string representation of the changes to be used for synchronization purposes.

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