How To Use The New acf/register_block_type_args Filter To Optimise ACF Block Registration

On March 26th, Advanced Custom Fields 5.8.9 was released. It was a relatively minor release, mainly including a couple of bug fixes, translation updates.

But this would be the release that changed everything about block registration.

Quietly, a new filter acf/register_block_type_args was introduced. This allows plugins or themes to modify the registration arguments of a block, similar to how register_post_type_args works for post types. More than that, it allows you to optimise how blocks are registered and we can do a few funky things with this new filter.

One thing we can do is set a common render callback for all blocks. Rather than create a different callback for each block, we can use the same callback and load a unique template based on the name of the block. This would be a bit of an effort if it was just to save writing one line of code while registering a block, but it also means we can have consistent block markup and handle common block settings like class, ID and alignment just once.

In the following example, we’ll be creating a template for each block, with the file name the same as the block name, in a theme subfolder called blocks. This template will be wrapped in a div with classes for the block alignment and custom classes.

add_filter( 'acf/register_block_type_args', 'cameronjonesweb_common_block_render_callback' );
function cameronjonesweb_common_block_render_callback( $args ) {
if ( empty( $args['render_callback'] ) ) {
$args['render_callback'] = 'cameronjonesweb_block_render_callback';
return $args;
function cameronjonesweb_block_render_callback( $block, $content = '', $is_preview = false, $post_id = 0 ) {
$block_class = '';
if ( isset( $block['className'] ) && ! empty( $block['className'] ) ) {
$block_class .= $block['className'];
if ( isset( $block['align'] ) && ! empty( $block['align'] ) ) {
$block_class .= ' align'$block['align'];
echo '<div class=" ' esc_attr( $block_class ) . '">';
get_template_part( 'blocks/' . $block['name'] . '/block.php' );
echo '</div>';

Now all you need to do after registering the block is create a new template, and you don’t need to worry about setting block classes in the template.

We can go one step further and automatically enqueue a block specific stylesheet when the block is used. This means your main theme stylesheet will be lighter and your block styles will only be included when needed.

add_filter( 'acf/register_block_type_args', 'cameronjonesweb_automatically_enqueue_block_stylesheet' );
function cameronjonesweb_automatically_enqueue_block_stylesheet( $args ) {
if ( empty( $args['enqueue_style'] ) ) {
$file = get_template_directory_uri() . '/blocks/' . ltrim( $args['name'], 'acf/' ) . '/block.css';
if ( file_exists( str_replace( get_template_directory_uri(), get_template_directory(), $file ) ) ) {
$args['enqueue_style'] = $file;
return $args;

As you can see, using the new acf/register_block_type_args can greatly optimise the way blocks are registered. What other ways can you optimise block registration with this new filter?

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