Adds optional new post states if a Post has Blocks, has the "Classic" Block or no Blocks at all. *** Note: This respects also the popular "Disable Gutenberg" plugin (free, by Jeff Starr) which allows for disabling the "Block Editor" for entire post types.

maybe-add-post-states-for-blocks.php

<?php
/** Do NOT include the opening php tag */


if ( ! function_exists( 'ddw_cf_maybe_add_post_state_blocks' ) ) :

	add_filter( 'display_post_states', 'ddw_cf_maybe_add_post_state_blocks', 10, 2 );
	/**
	 * Adds optional new post states if a Post has Blocks, has the "Classic" Block or no Blocks at all.
	 *
	 *   Note: This respects also the popular "Disable Gutenberg" plugin (free, by Jeff Starr) which allows for disabling the "Block Editor" for entire post types.
	 *
	 * @link https://github.com/WordPress/gutenberg/issues/12862
	 * @link https://www.billerickson.net/access-gutenberg-block-data/
	 * @link https://florianbrinkmann.com/bestimmte-gutenberg-bloecke-eines-beitrags-im-theme-an-anderer-stelle-ausgeben-6602/
	 *
	 * @since 1.0.0
	 *
	 * @author David Decker - DECKERWEB
	 * @link https://gist.github.com/deckerweb/32db10fcd1735e84023f265861e91eca
	 *
	 * @uses has_blocks()
	 * @uses parse_blocks()
	 * @uses disable_gutenberg_disable_post_type()	// from "Disable Gutenberg" plugin!
	 *
	 * @param array  $post_states Array holding all post states.
	 * @param object $post        Object of the current post type item.
	 * @return array Modified array of post states.
	 */
	function ddw_cf_maybe_add_post_state_blocks( $post_states, $post ) {

		/** Bail early if not on WP 5.0+ */
		if ( ! function_exists( 'parse_blocks' ) || ! function_exists( 'has_blocks' ) ) {
			return $post_states;
		}

		/** Initiate the Block parser */
	  	$blocks = parse_blocks( $post->post_content );
	  
	  	/** 1) Has some kind of block(s) */
		if ( $blocks && ! ( function_exists( 'disable_gutenberg_disable_post_type' ) && disable_gutenberg_disable_post_type() ) ) {

			if ( has_blocks( $post->post_content ) && NULL !== $blocks[0][ 'blockName' ] ) {

				/**
				 * 1st case: a post item with regular blocks (no "Classic" block!).
				 */
				$post_states[ 'ddwcf_has_blocks' ] = sprintf(
					'<span style="color: %2$s;">%1$s</span>',
					__( 'Has Blocks', 'Label for Post State', 'ddw-core-functionality' ),
					sanitize_hex_color( '#555' )
				);

		    } elseif ( ! has_blocks( $post->post_content ) && ( NULL === $blocks[0][ 'blockName' ] || ! empty( $blocks[0][ 'blockName' ] ) ) ) {

		    	/**
		    	 * 2nd case: a post item containing "Classic" block at the first position - usually a great sign for a post that can be transformed into regular Blocks.
		    	 */
		    	$post_states[ 'ddwcf_has_block_classic' ] = sprintf(
					'<span style="color: %2$s;">%1$s</span>',
					__( 'Classic Block', 'Label for Post State', 'ddw-core-functionality' ),
					sanitize_hex_color( '#00c' )
				);

		    }  // end if/elseif

		}

		/** 2) Has really NO blocks at all */
		else {

			/**
			 * 3rd case: a post item with NO regular blocks and NO "Classic" block in it.
			 */
			$post_states[ 'ddwcf_has_no_blocks' ] = sprintf(
			  '<span style="color: %2$s;">%1$s</span>',
			  __( 'No Blocks', 'Label for Post State', 'ddw-core-functionality' ),
			  sanitize_hex_color( '#c00' )
			);

		}  // end if/else

		/** Return modified Post States */
		return $post_states;

	}  // end function

endif;