[wp-trac] [WordPress Trac] #50105: Remove infinite scrolling behavior from the Media grid

[WordPress Trac]

#50105: Remove infinite scrolling behavior from the Media grid
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 Reporter:  afercia                  |       Owner:  (none)
     Type:  defect (bug)             |      Status:  new
 Priority:  normal                   |   Milestone:  5.5
Component:  Media                    |     Version:
 Severity:  normal                   |  Resolution:
 Keywords:  has-patch has-           |     Focuses:  ui, accessibility,
  screenshots                        |  javascript
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Changes (by afercia):

 * keywords:   => has-patch has-screenshots


Comment:

 [attachment:"50105.diff"] is a proof of concept meant for initial testing.

 Still to do:
 - update the number of total attachments when adding / removing
 attachments
 - more testing

 It would be great to run extended testing on different installations, with
 a varying mount of attachments stored in the media library. I'd suggest to
 focus on:
 - general behavior
 - whether the default "per page" of 40 attachments should be increased
 - filtering by type and date, keeping in mind there are existing bugs when
 filtering see for example #50025.

 **Suggestions for testing:**
 - styling of the button / spinner / etc. is temporary, please ignore it
 for now
 - throttle the network via your browser's dev tools: this helps in
 observing the UI behavior e.g. the spinner visibility
 - test without and with media trash enabled (by setting `define(
 'MEDIA_TRASH', true );` in your `wp-config.php` file)
 - test the filter `add_filter( 'media_library_infinite_scrolling',
 '__return_true' );` to restore the infinite scrolling behavior
 - test the Media Library
 - test the Media modal with Classic Editor (Add Media, featured image)
 - test the Media modal with Gutenberg (image, gallery, featured image...)
 - optionally: test the Media modal with plugins that implement custom
 frames to upload / select attachments
 - inspect the `queries` array of cached collections

 **Accessibility:**
 For now, clicking the "load more" sets focus on the first added
 attachment. I think it would be best to explore other options, as moving
 focus unexpectedly should preferably be avoided.

 **Questions:**

 1
 The patch changes the data returned by the WP_Query used to retrieve
 attachments. Previously, the response only held the array of attachments.
 Now, it holds 2 items:
 - the array of attachments
 - the number of total attachments, that is: `found_posts`

 Later, the response is parsed so that it passes the attachments array to
 the views and sets a new property for the number of total attachments.
 Basically, the response and the cached `queries` use a different format.
 An interesting question in this regard is: should the old format be kept
 when the `media_library_infinite_scrolling` filter restore infinite
 scrolling? The media grid works regardless but I guess this should be
 explored for potential backwards compatibility issues?

 2
 One more interesting question for anyone familiar with the history of the
 media views is what are the various "compat" methods meant for? This part
 is a bit obscure to me. See things like:
 - `Attachment.saveCompat`
 - the AJAX call `save-attachment-compat` and related
 `wp_ajax_save_attachment_compat`
 - the `attachment_fields_to_edit` things (I ''think'' this was used for
 the old upload method?)

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Ticket URL: <https://core.trac.wordpress.org/ticket/50105#comment:1>
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