Comment Template: Fix comment pagination with nested replies.

docs/reference-guides/core-blocks.md

@@ -204,7 +204,7 @@ An advanced block that allows displaying post comments based on different query
 -	**Name:** core/comments-query-loop
 -	**Category:** theme
 -	**Supports:** align (full, wide), color (background, gradients, link, text), ~~html~~
--	**Attributes:** inherit, order, perPage, tagName
+-	**Attributes:** defaultPage, inherit, order, perPage, tagName
 
 ## Cover
 

lib/compat/experimental/blocks.php

@@ -19,6 +19,7 @@ function build_comment_query_vars_from_block( $block ) {
 
 		$comment_args = array(
 			'orderby'                   => 'comment_date_gmt',
+			'order'                     => 'ASC',
 			'status'                    => 'approve',
 			'no_found_rows'             => false,
 			'update_comment_meta_cache' => false, // We lazy-load comment meta for performance.
@@ -34,29 +35,36 @@ function build_comment_query_vars_from_block( $block ) {
 			$comment_args['hierarchical'] = false;
 		}
 
-		$per_page = ! empty( $block->context['comments/perPage'] ) ? (int) $block->context['comments/perPage'] : 0;
-		if ( 0 === $per_page && get_option( 'page_comments' ) ) {
-			$per_page = (int) get_query_var( 'comments_per_page' );
-			if ( 0 === $per_page ) {
-				$per_page = (int) get_option( 'comments_per_page' );
-			}
+		$inherit = ! empty( $block->context['comments/inherit'] );
+
+		$per_page       = (int) get_option( 'comments_per_page' );
+		$query_per_page = (int) get_query_var( 'comments_per_page' );
+		if ( 0 !== $query_per_page ) {
+			$per_page = $query_per_page;
+		}
+		$block_per_page = ! empty( $block->context['comments/perPage'] ) ? (int) $block->context['comments/perPage'] : 0;
+		if ( ! $inherit && 0 !== $block_per_page ) {
+			$per_page = $block_per_page;
+		}
+
+		$default_page = get_option( 'default_comments_page' );
+		if ( ! $inherit && ! empty( $block->context['comments/defaultPage'] ) ) {
+			$default_page = $block->context['comments/defaultPage'];
 		}
+
 		if ( $per_page > 0 ) {
 			$comment_args['number'] = $per_page;
-			$page                   = (int) get_query_var( 'cpage' );
 
+			$page = (int) get_query_var( 'cpage' );
 			if ( $page ) {
-				$comment_args['offset'] = ( $page - 1 ) * $per_page;
-			} elseif ( 'oldest' === get_option( 'default_comments_page' ) ) {
-				$comment_args['offset'] = 0;
+				$comment_args['paged'] = $page;
+			} elseif ( 'oldest' === $default_page ) {
+				$comment_args['paged'] = 1;
+			} elseif ( 'newest' === $default_page ) {
+				$comment_args['paged'] = ( new WP_Comment_Query( $comment_args ) )->max_num_pages;
 			}
 		}
 
-		$comment_args['order'] = ! empty( $block->context['comments/order'] ) ? $block->context['comments/order'] : null;
-		if ( empty( $comment_args['order'] ) && get_option( 'comment_order' ) ) {
-			$comment_args['order'] = get_option( 'comment_order' );
-		}
-
 		return $comment_args;
 	}
 }
@@ -128,3 +136,27 @@ function extend_block_editor_settings_with_discussion_settings( $settings ) {
 	}
 }
 add_filter( 'block_editor_settings_all', 'extend_block_editor_settings_with_discussion_settings' );
+
+if ( ! function_exists( 'gutenberg_rest_comment_set_children_as_embeddable' ) ) {
+	/**
+	 * Mark the `children` attr of comments as embeddable so they can be included in
+	 * REST API responses without additional requests.
+	 *
+	 * @return void
+	 */
+	function gutenberg_rest_comment_set_children_as_embeddable() {
+		add_filter(
+			'rest_prepare_comment',
+			function ( $response ) {
+				$links = $response->get_links();
+				if ( isset( $links['children'] ) ) {
+					$href = $links['children'][0]['href'];
+					$response->remove_link( 'children', $href );
+					$response->add_link( 'children', $href, array( 'embeddable' => true ) );
+				}
+				return $response;
+			}
+		);
+	}
+}
+add_action( 'rest_api_init', 'gutenberg_rest_comment_set_children_as_embeddable' );

packages/block-library/src/comment-template/block.json

@@ -7,7 +7,13 @@
 	"parent": [ "core/comments-query-loop" ],
 	"description": "Contains the block elements used to render a comment, like the title, date, author, avatar and more.",
 	"textdomain": "default",
-	"usesContext": [ "comments/perPage", "postId", "comments/order" ],
+	"usesContext": [
+		"comments/defaultPage",
+		"comments/inherit",
+		"comments/order",
+		"comments/perPage",
+		"postId"
+	],
 	"supports": {
 		"reusable": false,
 		"html": false,

packages/block-library/src/comment-template/edit.js

@@ -1,7 +1,7 @@
 /**
  * WordPress dependencies
  */
-import { useState, useMemo, memo } from '@wordpress/element';
+import { useState, memo } from '@wordpress/element';
 import { useSelect } from '@wordpress/data';
 import { __ } from '@wordpress/i18n';
 import {
@@ -17,7 +17,7 @@ import { store as coreStore } from '@wordpress/core-data';
 /**
  * Internal dependencies
  */
-import { convertToTree } from './util';
+import { useCommentQueryArgs, useCommentTree } from './hooks';
 
 const TEMPLATE = [
 	[ 'core/comment-author-avatar' ],
@@ -106,10 +106,10 @@ function CommentTemplateInnerBlocks( {
 			{ comment === ( activeComment || firstComment ) ? children : null }
 
 			{ /* To avoid flicker when switching active block contexts, a preview
-			is ALWAYS rendered and the preview for the active block is hidden. 
-			This ensures that when switching the active block, the component is not 
+			is ALWAYS rendered and the preview for the active block is hidden.
+			This ensures that when switching the active block, the component is not
 			mounted again but rather it only toggles the `isHidden` prop.
-			
+
 			The same strategy is used for preventing the flicker in the Post Template
 			block. */ }
 			<MemoizedCommentTemplatePreview
@@ -209,60 +209,58 @@ const CommentsList = ( {
 
 export default function CommentTemplateEdit( {
 	clientId,
-	context: { postId, 'comments/perPage': perPage, 'comments/order': order },
+	context: {
+		postId,
+		'comments/perPage': perPage,
+		'comments/order': order,
+		'comments/defaultPage': defaultPage,
+		'comments/inherit': inherit,
+	},
 } ) {
 	const blockProps = useBlockProps();
 
 	const [ activeComment, setActiveComment ] = useState();
-	const {
-		commentOrder,
-		commentsPerPage,
-		threadCommentsDepth,
-		threadComments,
-	} = useSelect( ( select ) => {
-		const { getSettings } = select( blockEditorStore );
-		return getSettings().__experimentalDiscussionSettings;
+	const { commentOrder, threadCommentsDepth, threadComments } = useSelect(
+		( select ) => {
+			const { getSettings } = select( blockEditorStore );
+			return getSettings().__experimentalDiscussionSettings;
+		}
+	);
+
+	const commentQuery = useCommentQueryArgs( {
+		postId,
+		perPage,
+		defaultPage,
+		inherit,
 	} );
 
-	const { rawComments, blocks } = useSelect(
+	const { topLevelComments, blocks } = useSelect(
 		( select ) => {
 			const { getEntityRecords } = select( coreStore );
 			const { getBlocks } = select( blockEditorStore );
 
-			const commentQuery = {
-				post: postId,
-				status: 'approve',
-				context: 'embed',
-				order: order || commentOrder,
-			};
-
-			if ( order ) {
-				commentQuery.order = order;
-			}
 			return {
-				rawComments: getEntityRecords(
-					'root',
-					'comment',
-					commentQuery
-				),
+				// Request only top-level comments. Replies are embedded.
+				topLevelComments: commentQuery
+					? getEntityRecords( 'root', 'comment', commentQuery )
+					: null,
 				blocks: getBlocks( clientId ),
 			};
 		},
-		[ postId, clientId, order ]
+		[ clientId, commentQuery ]
 	);
-	// TODO: Replicate the logic used on the server.
-	perPage = perPage || commentsPerPage;
-	// We convert the flat list of comments to tree.
-	// Then, we show only a maximum of `perPage` number of comments.
-	// This is because passing `per_page` to `getEntityRecords()` does not
-	// take into account nested comments.
 
-	let comments = useMemo(
-		() => convertToTree( rawComments ).slice( 0, perPage ),
-		[ rawComments, perPage ]
+	order = inherit || ! order ? commentOrder : order;
+
+	// Generate a tree structure of comment IDs.
+	let commentTree = useCommentTree(
+		// Reverse the order of top comments if needed.
+		order === 'desc' && topLevelComments
+			? [ ...topLevelComments ].reverse()
+			: topLevelComments
 	);
 
-	if ( ! rawComments ) {
+	if ( ! topLevelComments ) {
 		return (
 			<p { ...blockProps }>
 				<Spinner />
@@ -271,20 +269,20 @@ export default function CommentTemplateEdit( {
 	}
 
 	if ( ! postId ) {
-		comments = getCommentsPlaceholder( {
+		commentTree = getCommentsPlaceholder( {
 			perPage,
 			threadComments,
 			threadCommentsDepth,
 		} );
 	}
 
-	if ( ! comments.length ) {
+	if ( ! commentTree.length ) {
 		return <p { ...blockProps }> { __( 'No results found.' ) }</p>;
 	}
 
 	return (
 		<CommentsList
-			comments={ comments }
+			comments={ commentTree }
 			blockProps={ blockProps }
 			blocks={ blocks }
 			activeComment={ activeComment }