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Use first non-empty Nav post as primary fallback for Nav block (#36740)
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* Use non-empty Nav post as fallback

* Remove code duplication

Addresses #36740 (comment)

* Extract finding non empty nav block to function

* Extract process of getting fallback to dedicated function

* Apply block prefix to functions

* Add additional safety check around parsing Nav blocks

* Extract function for removing null blocks and apply

* Check for empty parsed Nav blocks

* Improve function comment

Addresses #36740 (comment)

* Amend ordering params to approximate current wp_nav_menus behaviour

* Fetch Nav posts in query rather than filtering in memory

Implements suggestion from #36740 (comment)

* Improve comments

* Spacing

* Limit Nav Posts query to a single item

Co-authored-by: Adam Zielinski <adam@adamziel.com>

* Fix linting

* Improve function naming

Co-authored-by: Adam Zielinski <adam@adamziel.com>

Co-authored-by: Adam Zielinski <adam@adamziel.com>
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@getdave @adamziel
getdave and adamziel committed Nov 24, 2021
1 parent a07e386 commit 6ddf0fc
Showing 1 changed file with 84 additions and 12 deletions.
96 changes: 84 additions & 12 deletions packages/block-library/src/navigation/index.php
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Expand Up @@ -132,6 +132,83 @@ function block_core_navigation_render_submenu_icon() {
return '<svg xmlns="http://www.w3.org/2000/svg" width="12" height="12" viewBox="0 0 12 12" fill="none" role="img" aria-hidden="true" focusable="false"><path d="M1.50002 4L6.00002 8L10.5 4" stroke-width="1.5"></path></svg>';
}


/**
* Finds the first non-empty `wp_navigation` Post.
*
* @return WP_Post|null the first non-empty Navigation or null.
*/
function block_core_navigation_get_first_non_empty_navigation() {
// Order and orderby args set to mirror those in `wp_get_nav_menus`
// see:
// - https://github.com/WordPress/wordpress-develop/blob/ba943e113d3b31b121f77a2d30aebe14b047c69d/src/wp-includes/nav-menu.php#L613-L619.
// - https://developer.wordpress.org/reference/classes/wp_query/#order-orderby-parameters.
$navigation_posts = get_posts(
array(
'post_type' => 'wp_navigation',
'order' => 'ASC',
'orderby' => 'name',
'posts_per_page' => 1, // only the first post.
's' => '<!--', // look for block indicators to ensure we only include non-empty Navigations.
)
);
return count( $navigation_posts ) ? $navigation_posts[0] : null;

}

/**
* Filter out empty "null" blocks from the block list.
* 'parse_blocks' includes a null block with '\n\n' as the content when
* it encounters whitespace. This is not a bug but rather how the parser
* is designed.
*
* @param array $parsed_blocks the parsed blocks to be normalized.
* @return array the normalized parsed blocks.
*/
function block_core_navigation_filter_out_empty_blocks( $parsed_blocks ) {
$filtered = array_filter(
$parsed_blocks,
function( $block ) {
return isset( $block['blockName'] );
}
);

// Reset keys.
return array_values( $filtered );
}

/**
* Retrieves the appropriate fallback to be used on the front of the
* site when there is no menu assigned to the Nav block.
*
* This aims to mirror how the fallback mechanic for wp_nav_menu works.
* See https://developer.wordpress.org/reference/functions/wp_nav_menu/#more-information.
*
* @return array the array of blocks to be used as a fallback.
*/
function block_core_navigation_get_fallback_blocks() {
// Default to a list of Pages.
$fallback_blocks = array(
array(
'blockName' => 'core/page-list',
'attrs' => array(),
),
);

$navigation_post = block_core_navigation_get_first_non_empty_navigation();

// Prefer using the first non-empty Navigation as fallback if available.
if ( $navigation_post ) {
$maybe_fallback = block_core_navigation_filter_out_empty_blocks( parse_blocks( $navigation_post->post_content ) );

// Normalizing blocks may result in an empty array of blocks if they were all `null` blocks.
// In this case default to the (Page List) fallback.
$fallback_blocks = ! empty( $maybe_fallback ) ? $maybe_fallback : $fallback_blocks;
}

return $fallback_blocks;
}

/**
* Renders the `core/navigation` block on server.
*
Expand All @@ -143,7 +220,10 @@ function block_core_navigation_render_submenu_icon() {
*/
function render_block_core_navigation( $attributes, $content, $block ) {

// Flag used to indicate whether the rendered output is considered to be
// a fallback (i.e. the block has no menu associated with it).
$is_fallback = false;

/**
* Deprecated:
* The rgbTextColor and rgbBackgroundColor attributes
Expand Down Expand Up @@ -204,29 +284,21 @@ function render_block_core_navigation( $attributes, $content, $block ) {

// 'parse_blocks' includes a null block with '\n\n' as the content when
// it encounters whitespace. This code strips it.
$compacted_blocks = array_filter(
$parsed_blocks,
function( $block ) {
return isset( $block['blockName'] );
}
);
$compacted_blocks = block_core_navigation_filter_out_empty_blocks( $parsed_blocks );

// TODO - this uses the full navigation block attributes for the
// context which could be refined.
$inner_blocks = new WP_Block_List( $compacted_blocks, $attributes );
}

// If there are no inner blocks then fallback to rendering the Page List block.
// If there are no inner blocks then fallback to rendering an appropriate fallback.
if ( empty( $inner_blocks ) ) {
$is_fallback = true; // indicate we are rendering the fallback.
$attributes['__unstableMaxPages'] = 4; // set value to be passed as context to Page List block.

$page_list_block = array(
'blockName' => 'core/page-list',
'attrs' => array(),
);
$fallback_blocks = block_core_navigation_get_fallback_blocks();

$inner_blocks = new WP_Block_List( array( $page_list_block ), $attributes );
$inner_blocks = new WP_Block_List( $fallback_blocks, $attributes );
}

// Restore legacy classnames for submenu positioning.
Expand Down

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