Patterns: add the pattern name to pattern blocks when they are converted

[ramonopoly]

The editor has used metadata in pattern attributes since ​https://github.com/WordPress/gutenberg/pull/59251 to organize and sort patterns.

Patterns metadata allows the editor to distinguish patterns from other block groups, and from other patterns.

An initiative to introduce a special "simple" content only mode to patterns depends on this feature. For user-created and inserted patterns, the editor will render the block tree differently, and present specific controls and tools to the user.

See: See: ​https://github.com/WordPress/gutenberg/issues/71517

The feature is slated for WordPress 7.0.

For this feature to work however, the block editor needs to know that it is dealing with a pattern.

For patterns created in the editor, and for patterns returned by the patterns REST API endpoint, the status of "pattern" can be inferred.

However, many templates contain patterns, for example TT5's 404 template

​https://github.com/WordPress/wordpress-develop/blob/trunk/src/wp-content/themes/twentytwentyfive/templates/404.html#L5

The block editor could parse templates on the frontend to identify patterns upon insertion, but this would have an impact on performance, especially for large patterns.

Rather, let's leverage the existing patterns parser resolve_pattern_blocks to add this metadata to theme patterns before they're sent as a response from the REST APIs.

See: ​https://github.com/WordPress/wordpress-develop/blob/trunk/src/wp-includes/blocks.php#L1843

Builds upon ​https://github.com/WordPress/wordpress-develop/pull/10180

Props to @scruffian

Modifies the resolve_pattern_blocks function to include metadata for single-root patterns, allowing the pattern name and title to be stored in the block attributes. The metadata contains the patternName and name attributes.

This enables identification of patterns inside templates and allows for special treatment in the editor.

This will be used to test contentOnly editing (​https://github.com/WordPress/gutenberg/issues/71517), so that themes that use patterns automatically opt into this behaviour.

Trac ticket: https://core.trac.wordpress.org/ticket/64123

Is there other metadata we could/should add to patterns - some of them seem to also contain a longer description. It would be good to support as much metadata as possible IMO.

Is there other metadata we could/should add to patterns - some of them seem to also contain a longer description. It would be good to support as much metadata as possible IMO.

Good question. What do you think the editor might need? There are also optional categories and block types, which could come in handy if the editor ever wanted to extend "change design" to patterns bundled with templates.

I'm not sure.

The description would be useful for ​https://github.com/WordPress/gutenberg/pull/72574. Not sure about the others.

The description would be useful for ​https://github.com/WordPress/gutenberg/pull/72574.

Done!