Access block data with PHP using parse_blocks() and render_block()

The Gutenberg block editor organizes your content into discrete blocks, and WordPress includes functions for easily accessing the individual blocks within a post.

Here’s a quick summary of how the functions work, and examples of them in use.

Jump to Section:

  1. parse_blocks()
  2. render_block()
  3. Display blockquote from post
  4. Table of contents from headings
  5. ACF block data

parse_blocks()

This function converts the HTML comments and markup stored in post_content into an array of parsed block objects.

Usage: $blocks = parse_blocks( $post->post_content );

The post_content of my Style Guide looks like:

<!-- wp:paragraph {"fontSize":"large"} --> <p class="has-large-font-size">Lorem <strong>ipsum</strong> dolor <em>sit amet</em>, consectetur <a class="map-link" href="https://maps.google.com/?q=Houston,+TX">adipiscing elit</a>, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.</p> <!-- /wp:paragraph --> <!-- wp:heading {"level":1} --> <h1>Heading 1</h1> <!-- /wp:heading -->

After running it through parse_blocks(), it looks like:

Array ( [0] => Array ( [blockName] => core/paragraph [attrs] => Array ( [fontSize] => large ) [innerBlocks] => Array ( ) [innerHTML] => <p class="has-large-font-size">Lorem <strong>ipsum</strong> dolor <em>sit amet</em>, consectetur <a class="map-link" href="https://maps.google.com/?q=Houston,+TX">adipiscing elit</a>, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.</p> [innerContent] => Array ( [0] => <p class="has-large-font-size">Lorem <strong>ipsum</strong> dolor <em>sit amet</em>, consectetur <a class="map-link" href="https://maps.google.com/?q=Houston,+TX">adipiscing elit</a>, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.</p> ) ) [1] => Array ( [blockName] => [attrs] => Array ( ) [innerBlocks] => Array ( ) [innerHTML] => [innerContent] => Array ( [0] => ) ) [2] => Array ( [blockName] => core/heading [attrs] => Array ( [level] => 1 ) [innerBlocks] => Array ( ) [innerHTML] => <h1>Heading 1</h1> [innerContent] => Array ( [0] => <h1>Heading 1</h1> )

render_block()

This function takes a single parsed block object and returns the rendered HTML for that block.

Usage: echo render_block( $block );

Display blockquote from post

On my portfolio archive page, every 4th project includes a blockquote. You could pull this directly from the content of the portfolio item by looping through the blocks and displaying the core/quote block, if one is found.

Add this function to your theme, then call be_display_post_blockquote() to display the quote.

/** * Display blockquote from post * @link https://www.billerickson.net/access-gutenberg-block-data/ */ function be_display_post_blockquote() { global $post; $blocks = parse_blocks( $post->post_content ); foreach( $blocks as $block ) { if( 'core/quote' === $block['blockName'] ) { echo render_block( $block ); break; } } }

Table of contents from headings

In a previous tutorial I showed how to dynamically build a table of contents by parsing the HTML.

Converting the HTML to blocks makes this much easier. You loop through the blocks and find the core/heading ones.

The example below makes a simple ordered list of all the headings in the page. You could take this a step further and use $block['attrs']['level'] to make a nested list based on the heading level (ex: h3 is subordinate to h2).

/** * List post headings * @link https://www.billerickson.net/access-gutenberg-block-data/ */ function be_list_post_headings() { global $post; $blocks = parse_blocks( $post->post_content ); $headings = array(); foreach( $blocks as $block ) { if( 'core/heading' === $block['blockName'] ) $headings[] = wp_strip_all_tags( $block['innerHTML'] ); } if( !empty( $headings ) ) { echo '<ol class="table-of-contents">'; foreach( $headings as $heading ) echo '<li>' . $heading . '</li>'; echo '</ol>'; } }

Unfortunately WordPress does not store the heading’s ID as an anchor attribute, so you’ll still need to manipulate the HTML if you want to create anchor links (example).

ACF block data

If you have built a custom block with Advanced Custom Fields, you can easily access all the block data using this method.

ACF generates dynamic blocks. Rather than storing actual HTML, it stores all of the block data in the HTML comments and then dynamically renders it using the PHP file or function you specify.

I’m working on a site that includes a “Service” block. It has fields for title, anchor link, content, and “success story” (a linked post from elsewhere).

The homepage includes links to the top-level pages, as well as anchor links to each individual service block. I’m using parse_blocks() to find all of the acf/service blocks, then building the links using the $block['attrs'] data.

/** * Get service sections * @link https://www.billerickson.net/access-gutenberg-block-data/ */ function ea_get_service_sections() { $sections = array(); global $post; $blocks = parse_blocks( $post->post_content ); foreach( $blocks as $block ) { if( 'acf/service' !== $block['blockName'] ) continue; $title = $anchor = ''; if( !empty( $block['attrs']['data']['title'] ) ) $title = $block['attrs']['data']['title']; if( !empty( $block['attrs']['data']['anchor'] ) ) $anchor = $block['attrs']['data']['anchor']; if( empty( $anchor ) ) $anchor = $title; $sections[] = '<a href="' . get_permalink() . '#' . sanitize_title_with_dashes( $anchor ) . '">' . esc_html( $title ) . '</a>'; } if( empty( $sections ) ) return; echo '<ul class="service-sections">'; foreach( $sections as $section ) echo '<li>' . $section . '</li>'; echo '</ul>'; }

Bill Erickson

Bill Erickson is a freelance WordPress developer and a contributing developer to the Genesis framework. For the past 14 years he has worked with attorneys, publishers, corporations, and non-profits, building custom websites tailored to their needs and goals.

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Comments

  1. Camilo T says

    Hello, I am learning this from wordpress and above all about gutenberg, but I cannot get the nodes or items from the core / gallery
    Do you have a way to do it or a tutorial like this to learn a little more about the gallery?

    • Bill Erickson says

      It looks like the core/gallery block includes an array of the attachment ids used in the gallery. You can access it in $block['attrs']['ids'].

      Here’s some testing code I added to a local site:

      add_action( 'wp_footer', function() {
      	global $post;
      	$blocks = parse_blocks( $post->post_content );
      	foreach( $blocks as $block ) {
      		if( 'core/gallery' === $block['blockName'] ) {
      			ea_pp( $block );
      		}
      	}
      });
      

      And here’s the result: https://a.cl.ly/E0uz462K

      (Here’s my ea_pp() helper function).

  2. Christina says

    I am using a CPT with a template. I also want to control how the layout looks on the frontend of the site. The problem is that if you render the block based on block name, what happens when you have multiple blocks with the same name? I used the [‘atts’] and checked the array for a class name. Is there a better way that I’ve missed? Thanks!

    • Bill Erickson says

      I’m not exactly sure what you’re asking for here. Are you saying you have multiple blocks of the same type within a post and you want to pull a specific one? In that case yes, I think a custom class name would be the best way to identify it.

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