[wp-trac] [WordPress Trac] #41816: attachment_url_to_postid() should find post_id for URLs of intermediate size images

[WordPress Trac]

#41816: attachment_url_to_postid() should find post_id for URLs of intermediate
size images
-------------------------------------------------+-------------------------
 Reporter:  pbiron                               |       Owner:
     Type:  defect (bug)                         |      Status:  new
 Priority:  normal                               |   Milestone:  Awaiting
Component:  Media                                |  Review
 Severity:  normal                               |     Version:  trunk
 Keywords:  has-patch dev-feedback 2nd-opinion   |  Resolution:
  has-unit-tests                                 |     Focuses:
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Comment (by pbiron):

 Yet another thing I'd appreciate feedback on is the following.

 Suppose the `thumbnail` size is `150x150`, an image is uploaded and the
 thumbnail sized image is added to a post, e.g., the post content looks
 like:

 {{{
 blah, blah, blah

 <img src='http://example.com/wp-content/uploads/test-150x150.jpg' />

 yada, yada, yada
 }}}

 Then at a later time, the `thumbnail` size is changed to `100x100` and
 attachment metadata is updated for all existing images.  Even tho the
 image in that post will still display correctly,

 {{{
 $attachment_id = attachment_url_to_postid( 'http://example.com/wp-
 content/uploads/test-150x150.jpg' );
 }}}

 will not find it's post ID (since `_wp_attachment_metadata['sizes']` will
 no longer contain `test-150x150.jpg`) and it would be good if it could.

 The only ways I can think to solve this particular problem are very
 computationally expensive and/or prone to false positives.  Can anyone
 think an air-tight solution that is efficient?

 **Note**

 This particular question arises from my attempt to fix what I consider a
 bug in the exporter (see [[https://github.com/pbiron/wordpress-
 exporter-v2/issues/3|Exporter Redux: Issue 3]]).  An export with
 `post_type = post` will **not** contain the attachment and, hence, when
 imported into another site the image in that post will still point to the
 exporting site instead of being rewritten to point to a newly imported
 attachment.

 To address that exporter bug, I've written code that extracts attachment
 URLs from posts being exported, gets the attachment post ID using
 `attachment_url_to_postid()` (actually, until the patch in this ticket is
 accepted/merged, it uses a differently named function whose implementation
 is the same as in the patch) and adds those attachment posts to the
 export, but because of this problem that code is missing attachments such
 as the above.

 Granted, even if this problem is solved, there is still a chance the
 intermediate size in question is not available on the importing site, and
 hence, the image in the imported post wouldn't display.  But, //that//
 particular problem is relatively easy to fix by having the exporter add
 "metadata" to the WXR file for such intermediate image sizes which the
 importer could then add (using `add_image_size()`) temporarily during the
 import.

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Ticket URL: <https://core.trac.wordpress.org/ticket/41816#comment:4>
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