Implement a mechanism to register all block types from a block metadata collection

[felixarntz]

This PR introduces a new function wp_register_block_types_from_metadata_collection() which can be used to register all block types from a block metadata collection.

It can be used in two different ways:

• Either to register all block types from a previously registered metadata collection, by referencing its path: wp_register_block_types_from_metadata_collection( WP_PLUGIN_DIR . '/my-plugin/blocks' )
  • In this scenario, the block metadata collection must have been registered prior, via wp_register_block_metadata_collection( WP_PLUGIN_DIR . '/my-plugin/blocks', /* manifest file path */ ). Otherwise this call would fail with a warning.
• Or by registering a new block metadata collection and then registering all its block types in the same function call: wp_register_block_types_from_metadata_collection( WP_PLUGIN_DIR . '/my-plugin/blocks', WP_PLUGIN_DIR . '/my-plugin/block-manifest-json.php' )

For additional context on what block metadata collections are and how to use them, see the WordPress 6.7 dev note about block metadata collections.

Trac ticket: https://core.trac.wordpress.org/ticket/62267

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[github-actions]

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[felixarntz]

@gziolo @mreishus When looking at the code as I was starting to work on this, the idea of a new arguments array to also register the block types as part of the existing wp_register_block_metadata_collection() function seemed not ideal to me. I think a new function (like wp_register_block_types_from_metadata_collection()) is a more elegant solution as it separates concerns better. The two functions can be used together, but if someone wants to do it all in one function they can. And while in the latter case, the two functions still get intertwined, at least there is a clear difference in intent:

• One function's purpose is to register a block metadata collection.
• The other function's purpose is to register block types from a block metadata collection.

Please let me know what you think about this approach.

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The other thing I'm wondering about is whether we can possibly use this for the Core blocks. The caveat is that many core blocks still provide a custom render_callback argument that is not possible to handle that way via block.json. Very few Core blocks also specify skip_inner_blocks, but I think those two arguments is all I could find.

A potential solution I thought about is that we could allow an optional callback function to dynamically compute additional $args based on the given block type name. For Core's usage, such a function implementation could look like this:

function get_args_for_block_type( string $block_name ) {
	$args = array();

	$function_name = 'render_block_core_' . str_replace( '-', '_', $block_name );
	if ( function_exists( $function_name ) ) {
		$args['render_callback'] = $function_name;
	}

	$blocks_to_skip_inner_blocks = array( /* Block name list. */ );
	if ( in_array( $block_name, $blocks_to_skip_inner_blocks, true ) ) {
		$args['skip_inner_blocks'] = true;
	}

	return $args;
}

Do you think something like this would be worthwhile? Or is it overkill and we should instead update to use block.json for everything and encourage others to do so too?

[github-actions]

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[swissspidy]

Dumb question, but why is block type registration made so complicated in the first place? Why didn't we support something like the following?

foreach ( require 'path/to/blocks-json.php' as $block_type => $metadata ) {
	register_block_type_from_metadata( $block_type, $metadata );
}

This would help me better understand the context of this PR for doing a review.

Right now my first impression is that this is overly complex and that WP_Block_Metadata_Registry is just a glorified global variable and file reader.

[mukeshpanchal27]

Suggested change

	// Load the manifest file if not already loaded
	// Load the manifest file if not already loaded.

Why PHPCS didn't show issue 🤔