[wp-trac] [WordPress Trac] #45381: importer should remap attachment IDs when they appear in a block's attributes

[WordPress Trac]

#45381: importer should remap attachment IDs when they appear in a block's
attributes
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 Reporter:  pbiron       |      Owner:  (none)
     Type:  enhancement  |     Status:  new
 Priority:  normal       |  Milestone:  Awaiting Review
Component:  Import       |    Version:
 Severity:  normal       |   Keywords:  dev-feedback
  Focuses:               |
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 Related: https://github.com/WordPress/gutenberg/issues/10535

 > One idiosyncrasy of the WordPress Importer is that attachment ids can
 change in the import process. If an existing WordPress site already has a
 number of posts, those existing post ids can conflict with the post ids
 included in the import file.
 >
 > To accommodate the changing ids, the WordPress Importer has
 backfill_parents() (ref) and remap_featured_images() (ref). Both of these
 methods use a mapping of old=>new post ids to update existing references
 to the old ids.
 >
 > Along the same lines, Image Blocks will need their attachment ids
 updated, otherwise they can end up in a crashed state. To replicate what
 the user will experience, simply insert an Image Block and change its
 attachment id reference to an invalid id:

 I've done some experimenting and the mods to importer to support such
 remapping are fairly minor.  Before submitting a patch I'll have to
 account for the recent change in the Gallery block
 (https://github.com/WordPress/gutenberg/pull/11540).

 The mods I have work only if the attachments in question are included in
 the same export/import as the posts that have blocks that reference them.
 For example, if you export posts separately from Media and do 2 separate
 imports the IDs are not remapped. If the attachments are not included in
 the same export as the posts that reference them, then the importer
 currently does not remap the URLs in post_content either whether the media
 is referenced in a block or in "classic" content (i.e., they still point
 to URLs on the exporting host)...so I do not think that is a major flaw in
 what I've written :-)

 I do not see any way around that, but wanted to mention it in case anyone
 has any bright ideas...before I finalize and submit that patch.

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Ticket URL: <https://core.trac.wordpress.org/ticket/45381>
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