Feature idea: User defined Snapshots (description only snapshots)

[blueo]

Snapshots are currently great for recording standard editing activity (creation modification etc) but it would be useful to be able to create a snapshot for an action that is more of a description rather than a log of events. This is often the case when a user action might trigger several edit/write actions. For example, re-ordering blocks can trigger a number of snapshot entries like Block x Edited but it would be more useful to have a single snapshot that captures the 're-order' action.

I can achieve something like this by creating a DataObject as a 'Log' and manually creating a snapshot with it eg:

class Log extends DataObject
{
    /**
     * @var array
     */
    private static $extensions = [
        Versioned::class,
    ];
    /**
     * @var string
     */
    private static $table_name = 'SnapshotActivitiesLog';
    /**
     * @var array
     */
    private static $db = [
        'Title' => 'Varchar',
    ];
}

then:

    /**
     * Create a snapshot with a Log item to record arbitrary actions
     * in the snapshot viewer
     *
     * @param DataObject $origin
     * @return Log
     */
    public static function createLog(DataObject $origin, string $message = ''): Log
    {
        $log = Log::create();
        $log->Title = $message;
        $log->write();
        $snapshot = self::createSnapshot($log);
        $locale = Locale::getCurrentLocale();
        $snapshot->LocaleID = $locale->ID;
        $snapshot->write();
        $snapshot->Items()->add($log->createSnapshotItem());
        $snapshotItem = $origin->createSnapshotItem();
        $snapshot->Items()->add($snapshotItem);
        return $log;
    }

This creates a single snapshot with a message representing the action.

replacing multiple snapshots with a single one can also reduce the performance impact of writing multiple snapshots.

Putting this out there as there are probably other (better) ways to do this? But if it is useful I could make up a PR for the above.