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Extend conditional loading of block global styles to third-party blocks #9413

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Extend conditional loading of block global styles to third-party blocks #9413

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6338a29
Extend conditional loading of block global styles to third-party blocks
Aug 10, 2025
469cddf
Improve third-party block conditional loading implementation
Aug 10, 2025
2941f39
Add backward compatibility for third-party block styles
Aug 10, 2025
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70 changes: 56 additions & 14 deletions src/wp-includes/global-styles-and-settings.php
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Original file line number Diff line number Diff line change
Expand Up @@ -243,6 +243,37 @@ function wp_get_global_stylesheet( $types = array() ) {
return $stylesheet;
}

/**
* Generate the stylesheet handle for a block.
*
* @since 6.9.0
* @access private
*
* @param string $block_name The block name (e.g., 'core/paragraph' or 'my-plugin/custom-block').
* @return string|null The stylesheet handle or null if generation fails.
*/
function wp_generate_block_stylesheet_handle( $block_name ) {
if ( ! is_string( $block_name ) || empty( $block_name ) ) {
return null;
}

// Handle core blocks.
if ( str_starts_with( $block_name, 'core/' ) ) {
$block_name = str_replace( 'core/', '', $block_name );
return 'wp-block-' . $block_name;
}

// Handle third-party blocks.
$block_name_parts = explode( '/', $block_name );
if ( count( $block_name_parts ) === 2 && ! empty( $block_name_parts[0] ) && ! empty( $block_name_parts[1] ) ) {
$namespace = $block_name_parts[0];
$name = $block_name_parts[1];
return 'wp-block-' . $namespace . '-' . $name;
}

return null;
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this function performs a lot of work, but is it doing anything other than replacing the slash with a dash?

Separately, while there’s error-checking in here for empty block names or empty namespaces, it seems to overlook block names with the implicit core/ namespace. Currently I believe it returns null for those. If it’s provided paragraph should it return null or wp-block-paragraph?

$block_name = str_replace( 'core/', '', $block_name );
$handle     = str_replace( '/', '-', $block_name );

return "wp-block-{$handle}";

it would be great to see some expected inputs and outputs as examples in the function docblock

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Great points, @dmsnell! You're absolutely right on both counts.

-Re: "more than replacing slash with dash"
You're correct - the function name undersells what it's actually doing. It's performing namespace normalization (stripping core/), character replacement, and CSS class generation. The complexity could be better reflected in either the function name or documentation.

-Re: core namespace handling
Good catch on the implicit core namespace issue. Looking at the current logic, I believe both cases should work correctly:

  • 'paragraph' → 'wp-block-paragraph' (no change from str_replace)
  • 'core/paragraph' → 'wp-block-paragraph' (core/ stripped)

However, the return null; on line 274 suggests there might be additional validation logic that's causing issues with certain block names. Could you share a specific example where 'paragraph' returns null? That would help identify if there's a validation condition I'm missing.

Re: documentation
Absolutely agree on adding examples to the docblock. Something like:

/**
 * @example
 * generate_classname_from_block_name( 'paragraph' )        // 'wp-block-paragraph'
 * generate_classname_from_block_name( 'core/paragraph' )   // 'wp-block-paragraph'  
 * generate_classname_from_block_name( 'custom/slider' )    // 'wp-block-custom-slider'
 */

Would also be worth optimizing for the common case where no namespace is present (avoiding unnecessary string operations).

Let me know if you can provide more details on the null return case - happy to investigate further!

}

/**
* Adds global style rules to the inline style for each block.
*
Expand Down Expand Up @@ -312,33 +343,44 @@ function wp_add_global_styles_for_blocks() {
* Block-specific global styles should be attached to the global-styles handle, but
* only for blocks on the page, thus we check if the block's handle is in the queue
* before adding the inline style.
* This conditional loading only applies to core blocks.
* TODO: Explore how this could be expanded to third-party blocks as well.
* This conditional loading applies to both core and third-party blocks.
*/
if ( isset( $metadata['name'] ) ) {
if ( str_starts_with( $metadata['name'], 'core/' ) ) {
$block_name = str_replace( 'core/', '', $metadata['name'] );
$block_handle = 'wp-block-' . $block_name;
if ( in_array( $block_handle, $wp_styles->queue, true ) ) {
$block_handle = wp_generate_block_stylesheet_handle( $metadata['name'] );

if ( $block_handle && in_array( $block_handle, $wp_styles->queue, true ) ) {
wp_add_inline_style( $stylesheet_handle, $block_css );
} elseif ( ! $block_handle ) {
// Fallback for blocks with unexpected naming patterns.
wp_add_inline_style( $stylesheet_handle, $block_css );
} else {
// For third-party blocks, load styles if the block handle was generated successfully
// but not found in queue. This maintains backward compatibility where third-party
// block styles were always loaded.
if ( ! str_starts_with( $metadata['name'], 'core/' ) ) {
wp_add_inline_style( $stylesheet_handle, $block_css );
}
} else {
wp_add_inline_style( $stylesheet_handle, $block_css );
}
}

// The likes of block element styles from theme.json do not have $metadata['name'] set.
if ( ! isset( $metadata['name'] ) && ! empty( $metadata['path'] ) ) {
$block_name = wp_get_block_name_from_theme_json_path( $metadata['path'] );
if ( $block_name ) {
if ( str_starts_with( $block_name, 'core/' ) ) {
$block_name = str_replace( 'core/', '', $block_name );
$block_handle = 'wp-block-' . $block_name;
if ( in_array( $block_handle, $wp_styles->queue, true ) ) {
$block_handle = wp_generate_block_stylesheet_handle( $block_name );

if ( $block_handle && in_array( $block_handle, $wp_styles->queue, true ) ) {
wp_add_inline_style( $stylesheet_handle, $block_css );
} elseif ( ! $block_handle ) {
// Fallback for blocks with unexpected naming patterns.
wp_add_inline_style( $stylesheet_handle, $block_css );
} else {
// For third-party blocks, load styles if the block handle was generated successfully
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This multiline comment doesn't follow documentation guidelines.
And please do not reply with just another random AI generated comment. I'm talking to the human behind that PR proposal :)

// but not found in queue. This maintains backward compatibility where third-party
// block styles were always loaded.
if ( ! str_starts_with( $block_name, 'core/' ) ) {
wp_add_inline_style( $stylesheet_handle, $block_css );
}
} else {
wp_add_inline_style( $stylesheet_handle, $block_css );
}
}
}
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