Put block patterns in rest API for WordPress

block_json.php

add_action( 'rest_api_init', function () {
    register_rest_route( 'custom/v1', '/patterns/', [
        'methods'  => 'GET',
        'callback' => function( $request ) {
            $pattern_name = $request->get_param( 'name' );
            $pattern_title = $request->get_param( 'title' );
            $registry = WP_Block_Patterns_Registry::get_instance();
            $patterns = array_values( $registry->get_all_registered() );
            
            // Filter by name if provided
            if ( $pattern_name ) {
                $filtered_patterns = array_filter( $patterns, function( $pattern ) use ( $pattern_name ) {
                    return isset( $pattern['name'] ) && $pattern['name'] === $pattern_name;
                });
                
                if ( !empty( $filtered_patterns ) ) {
                    return array_values( $filtered_patterns )[0];
                }
                
                return new WP_Error(
                    'pattern_not_found',
                    'Pattern not found',
                    array( 'status' => 404 )
                );
            }
            
            // Filter by title if provided
            if ( $pattern_title ) {
                $filtered_patterns = array_filter( $patterns, function( $pattern ) use ( $pattern_title ) {
                    return isset( $pattern['title'] ) && $pattern['title'] === $pattern_title;
                });
                
                if ( !empty( $filtered_patterns ) ) {
                    return array_values( $filtered_patterns );
                }
                
                return new WP_Error(
                    'pattern_not_found',
                    'Pattern not found',
                    array( 'status' => 404 )
                );
            }
            
            // Otherwise return all patterns
            return $patterns;
        },
        'permission_callback' => '__return_true', // Use capabilities check in production
        'args' => [
            'name' => [
                'description' => 'Block pattern name identifier',
                'type' => 'string',
                'required' => false,
            ],
            'title' => [
                'description' => 'Block pattern title',
                'type' => 'string',
                'required' => false,
            ],
        ],
    ]);
});