parsing nested blocks (in columns, etc) via PHP

Question

I'm checking posts for a custom block and trying to render the content of those blocks elsewhere in the site via PHP. My method for doing that looks like this:

      if ( has_block( 'custom/block' ) ) {
        global $post;

        $blocks = parse_blocks( $post->post_content );
        foreach ( $blocks as $block ) {
          if ( 'custom/block' === $block['blockName'] ) {
              echo "<div>";
              echo apply_filters( 'the_content', render_block( $block ) );
              echo "</div>";
              break;
          } 
      }

So I basically check the post for a specific block, when I find it I output its contents, then break the loop because I only care about the first one. The problem is that when you put the 'custom/block' in a column block (or anything similar I'm assuming) then this loop will miss it. I'm not sure how to effectively investigate a block's innerblocks to solve this problem, other than something like iterating over all possible parent blocks and checking their guts like so:

      if ( has_block( 'custom/block' ) ) {
        global $post;

        $blocks = parse_blocks( $post->post_content );
        foreach ( $blocks as $block ) {
          if ( 'custom/block' === $block['blockName'] ) {
              echo "<div>";
              echo apply_filters( 'the_content', render_block( $block ) );
              echo "</div>";
              break;
          } elseif ( 'core/columns' === $block['blockName'] ) {
            $column = apply_filters( 'the_content', render_block( $block ) );
            // mess around with the $column here to get the appropriate equivalent output
          }
          // elseif iterate through other potential parent blocks
      }

Any suggestions to make this less messy?

Answer 1

If I understand it correctly, you can use a recursive function which loops through inner blocks to find the specific block. Example:

/* Sample usage, assuming $post is defined properly:

    $blocks = parse_blocks( $post->post_content );
    wpse_387661( $blocks );
*/
function wpse_387661( $blocks ) {
    foreach ( $blocks as $block ) {
        if ( ! empty( $block['innerBlocks'] ) ) {
             wpse_387661( $block['innerBlocks'] );
        } elseif ( 'custom/block' === $block['blockName'] ) {
            echo apply_filters( 'the_content', render_block( $block ) );
            break; // this could mean that inner blocks were never looped
        }
    }
}