template-part-block-renderer.php

<?php

namespace Foo\Blocks;

/**
 * Generic block rendering callback function to load a block from a theme template part.
 *
 * Loads a block from the `blocks` subdirectory according to the name of the block, and places the
 * block attributes and block content into namespaced query vars. If there's no corresponding block
 * template part, the block content is returned unaltered.
 *
 * A block named `foo/block1` looks for a template part named `blocks/foo/block1.php`.
 *
 * The block attributes and content can be accessed inside the template part via query vars:
 *
 * - `get_query_var( 'foo/block1/attribute1' )`
 * - `get_query_var( 'foo/block1/attribute2' )`
 * - `get_query_var( 'foo/block1/content' )`
 *
 * @param string $name       The full block name, for example 'foo/block1'.
 * @param array  $attributes Array of attributes saved on the block instance.
 * @param string $content    Optional user-entered block content. Can be null.
 * @return string The dynamic block content.
 */
function template_part_block_renderer( string $name, array $attributes, string $content = null ) : string {
	// Set query vars so they are accessible to the template part:
	foreach ( $attributes as $attribute_name => $attribute_value ) {
		set_query_var( $name . '/' . $attribute_name, $attribute_value );
	}
	set_query_var( $name . '/content', $content );

	// Load the template part in an output buffer:
	ob_start();
	get_template_part( 'blocks/' . $name );
	$output = ob_get_clean();

	// Fall back to just the block content if there's no template part:
	if ( '' === $output ) {
		$output = (string) $content;
	}

	// Clear the query vars so they don't bleed into subsequent instances of the same block type
	foreach ( $attributes as $attribute_name => $attribute_value ) {
		set_query_var( $name . '/' . $attribute_name, null );
	}
	set_query_var( $name . '/content', null );

	return $output;
}

$blocks = [
	'block1',
	'block2',
	'block3',
];

foreach ( $blocks as $block ) {
	register_block_type( "foo/{$block}", [
		// https://github.com/WordPress/gutenberg/issues/4671
		'render_callback' => function( array $attributes, string $content = null ) use ( $block ) {
			return template_part_block_renderer( "foo/{$block}", $attributes, $content );
		},
	] );
}