Editing Updating Cached Front-Facing Content After Gallery Edits

== Overview ==

Documentation of the process of refreshing cached front-facing content after editing gallery images in the Albums CMS.

== Use cases ==

* Add a new image to the gallery
* Edit an existing image in the gallery
* Delete an existing image in the gallery
* Click "update cache" button for the gallery
* Update the Album's cache

== Considerations ==

The routine that generates the gallery listings markup for the CMS should be separate from the routine that is run after editing operations. 

Toggling a gallery, or fetching a gallery on an album's details page should not cause the front-end cache to be updated even though the editing AJAX operations and viewing AJAX operations should share the logic that generates the gallery listings markup.

== Operations requiring cache updates ==

* Add a page/image to a gallery.
* Edit a page/image in a gallery.
* Delete a page/image in a gallery.
* Change the order of pages/images in a gallery.

== Operations and their shared default handlers ==

* Add/edit a page image
** `/_ajax/images/edit_image.php`
** `cache_class::refresh_content_after_edit()` &rarr; `cache_class::refresh_content_after_image_edit()` 
* Delete a page image
** `/_ajax/images/del_image.php`
** `cache_class::refresh_content_after_edit()` &rarr; `cache_class::refresh_content_after_image_edit()` 
* Fetch gallery listings markup
** `/_ajax/images/gallery_listings.php`
** `cache_class::retrieve_gallery_listings_content()` falling back on `cache_class::refresh_content_after_edit()` 
* Resort page images
** `/_ajax/utils/resort.php`
** `resort_class` (local to site) &rarr; `resort_base_class` (shared)
** `resort_class::save()` (after calling `resort_class::update_positions()`)
** <span style="font-style:italic;color:red">N.B. The logic to update the front-end content cache doesn't exist in this routine currently.</span>
** The logic to implement updating the front-end content cache should probably be added to `/_ajax/utils/resort.php` after the call to `resort_class::update_positions()`
*** Include `cache_class` if it exists on the local site.
*** If `cache_class` has method `update_frontend_content_cache()`
**** Load the appropriate object (using `cache_class::set_content_and_filters()`
**** Call `cache_class::update_frontend_content_cache()`

== Adding logic to update front-end cached content after page image edits ==

The site's local `cache_class` should have 2 routines defined: `refresh_content_after_image_edit($content, $filters, $json)` and `retrieve_gallery_listings_content($content, $filters, $json)`.

`cache_class::retrieve_gallery_listings_content()` simply loads the gallery listings template, populates it with data, and returns the resulting markup.

`cache_class::refresh_content_after_image_edit()` calls `cache_class::retrieve_gallery_listings_content()` and then executes the logic to update the front-end cached content.

For example:

<syntaxhighlight lang="php">
	public static function refresh_content_after_image_edit ( &$content, &$filters, &$json )
	{
		switch($content->site_section->id->value)
		{
			case comics_class::PAGE_SECTION_ID:
			case sketchbook_class::PAGE_SECTION_ID:
			case stasis_class::PAGE_SECTION_ID:

				cache_class::retrieve_gallery_listings_content($content, $filters, $json);
				cache_class::update_parent_frontend_cache($content, $filters, $json);
				break;
		}
	}

	public static function update_parent_frontend_cache( &$content, &$filters, &$json )
	{
		if ($content instanceof image_link_class)
		{
			if ($content->parent_id->value > 0)
			{
				$parent = null;
				$content_type_id = $content->get_parent_content_type_id();
				if ($content_type_id)
				{
					cache_class::set_content($content_type_id, $parent);
					if (is_object($parent) && method_exists($parent, "update_cache"))
					{
						$parent->id->value = $content->parent_id->value;
						$parent->read(true);
						$json->status->value .= $parent->update_cache();
					}
				}
			}
		}
	}

</syntaxhighlight>

== Examples ==

* [http://damienjay.com/hostmgr/comics/|damienjay.com comics and sketchbook CMS]

[[Category:Albums CMS]]
[[Category:CMS Documentation]]
[[Category:JQuery/AJAX]]