Helper functions to cleanly alter versioned objects in SilverStripe

silverstripe-versioned-helpers.php

<?php
/**
 * Helper functions to cleanly alter versioned objects in SilverStripe.
 * 
 * Usage:
 * 
 *	whileDraft(function() {
 *		$page = Page::get()->byId(123);
 *		// ... with great power comes great responsibility...
 *	});
 *
 * @author	Patrick Nelson, pat@catchyour.com
 * @since	2018-12-28
 */


/**
 * Synchronous way to temporarily change global state to the desired reading mode. Unfortunately these things aren't as
 * easy in the framework as they should be...
 *
 * @param	string		$name
 * @param	callable	$closure
 * @return	mixed
 */
function whileStage($name, callable $closure) {
	// Normalize desired stage name.
	$normName = strtolower(trim($name));
	$readingMode = 'Stage.Live'; // Default to live, just in case.
	if ($normName === 'draft') $readingMode = 'Stage.Stage'; // ... yes, the redundancy is an artifact of our dear friend SilverStripe.

	// Don't normalize but pass through directly if 'Archive' is specified, given the possible variation.
	if (substr($normName, 0, 8) === 'archive.') $readingMode = $name;

	// Get global state.
	$oldReadingMode = Versioned::get_reading_mode();

	// Change global state temporarily to the mode we want to be in and run the code.
	Versioned::set_reading_mode($readingMode);
	$retval = call_user_func($closure);

	// Clean up global state and return.
	Versioned::set_reading_mode($oldReadingMode);
	return $retval;
}

/**
 * Allows you to read archived pages (i.e. from *_versions table) for a particular
 *
 * @param	int			$timestamp	Specific UNIX timestamp to rewind in history back to. Versions of pages  will be
 * 									those at/before this particular point in time.
 * @param	callable	$closure
 * @return	mixed
 */
function whileArchive($timestamp, callable $closure) {
	return whileStage('Archive.' . date('Y-m-d H:i:s', $timestamp), $closure);
}


/**
 * Shortcut to whileStage().
 *
 * @param	callable	$closure
 * @return	mixed
 */
function whileDraft(callable $closure) {
	return whileStage('draft', $closure);
}


/**
 * Shortcut to whileStage().
 *
 * @param	callable	$closure
 * @return	mixed
 */
function whileLive(callable $closure) {
	return whileStage('live', $closure);
}