Page sub-categories on their own, with how much each holds

README.md

@@ -127,7 +127,7 @@ Write `[[Category:Name]]` anywhere in a wiki article to put it in a category. Th
 - `[[Category:boxes]]` and `[[Category:Boxes]]` are the same category: the first letter is capitalised and underscores count as spaces.
 - **Sort keys:** `[[Category:Boxes|Small]]` files the article under "Small" in that category's list instead of under its title. If an article names a category twice, the first key counts.
 - **Linking to a category:** `[[:Category:Boxes]]`, with a colon in front, is a plain link to the category's page and does not put the article in it.
-- **Sub-categories:** a category page that is itself in a category (`Category:Extensions` with `[[Category:Software]]` in it) is listed as a sub-category on that category's page, above its articles.
+- **Sub-categories:** a category page that is itself in a category (`Category:Extensions` with `[[Category:Software]]` in it) is listed as a sub-category on that category's page, above its articles, with how many articles (and sub-categories) it holds. Sub-categories have their own pages, so moving through them keeps the page of articles, and the other way round.
 - **A category page** is the article `Category:Name`, at `/wiki/Category:Name`. If nobody wrote it, the page still exists as a list of the articles in the category, by sort key or title, with their descriptions, with a link to write a description. If an article called `Category:Name` exists, its text is shown above the list, and it has the usual edit and version buttons.
 - **`/wiki/categories`** lists every category with a live article in it, how many, and its description (the description field of its `Category:Name` article), linked from the overview. A **How to use categories** box above the list explains `[[Category:Name]]` and category pages, plus, for members who can edit, how to describe a category. Under each category, **Articles in it and how to add one** opens the line to write and its first five articles. Category pages are left out of the overview's article lists.
 - Only the live version of an article counts. A forum post keeps `[[Category:Name]]` as plain text, like the rest of the wiki markup.

controller/category.php

@@ -96,20 +96,34 @@ public function __construct(\phpbb\auth\auth $auth, \phpbb\config\config $config
 	 */
 	protected function assign_members($name)
 	{
-		// Categories that are in this one, by sort key or else name
-		foreach ($this->categories->subcategories($name) as $row)
+		$per_page = max(1, (int) $this->config['topics_per_page']);
+
+		// Categories that are in this one, by sort key or else name, paged on their own (substart)
+		// so moving through them keeps the page of articles, and the other way round
+		$subcategories = $this->categories->subcategories($name);
+		$sub_total = count($subcategories);
+		$sub_start = $this->pagination->validate_start($this->request->variable('substart', 0), $per_page, $sub_total);
+		$members = $this->categories->members($name);
+		$total = count($members);
+		$start = $this->pagination->validate_start($this->request->variable('start', 0), $per_page, $total);
+
+		$shown = array_slice($subcategories, $sub_start, $per_page);
+		$counts = $this->categories->counts(array_map(function ($row) {
+			return substr($row['article_url'], strlen(categories::PREFIX));
+		}, $shown));
+		foreach ($shown as $row)
 		{
+			$sub_name = categories::normalise(substr($row['article_url'], strlen(categories::PREFIX)));
+			$count = isset($counts[$sub_name]) ? $counts[$sub_name] : array('articles' => 0, 'subcategories' => 0);
 			$this->template->assign_block_vars('category_subcategories', array(
-				'NAME'			=> substr($row['article_url'], strlen(categories::PREFIX)),
+				'NAME'			=> $sub_name,
 				'DESCRIPTION'	=> $row['article_description'],
+				'COUNT'			=> $this->user->lang('WIKI_CATEGORY_HOLDS_ARTICLES', $count['articles'])
+					. ($count['subcategories'] ? ', ' . $this->user->lang('WIKI_CATEGORY_HOLDS_SUBCATEGORIES', $count['subcategories']) : ''),
 				'U_CATEGORY'	=> $this->helper->route('phpbbmodders_wiki_article', array('article' => $row['article_url'])),
 			));
 		}
-
-		$members = $this->categories->members($name);
-		$total = count($members);
-		$per_page = max(1, (int) $this->config['topics_per_page']);
-		$start = $this->pagination->validate_start($this->request->variable('start', 0), $per_page, $total);
+		$this->pagination->generate_template_pagination($this->helper->route('phpbbmodders_wiki_category', array('name' => $name) + ($start ? array('start' => $start) : array())), 'sub_pagination', 'substart', $sub_total, $per_page, $sub_start);
 
 		foreach (array_slice($members, $start, $per_page) as $row)
 		{
@@ -121,10 +135,11 @@ protected function assign_members($name)
 			));
 		}
 
-		$this->pagination->generate_template_pagination($this->helper->route('phpbbmodders_wiki_category', array('name' => $name)), 'pagination', 'start', $total, $per_page, $start);
+		$this->pagination->generate_template_pagination($this->helper->route('phpbbmodders_wiki_category', array('name' => $name) + ($sub_start ? array('substart' => $sub_start) : array())), 'pagination', 'start', $total, $per_page, $start);
 		$this->template->assign_vars(array(
-			'S_CATEGORY_PAGE'	=> true,
-			'CATEGORY_TOTAL'	=> $this->user->lang('WIKI_CATEGORY_ARTICLES_TOTAL', $total),
+			'S_CATEGORY_PAGE'			=> true,
+			'CATEGORY_TOTAL'			=> $this->user->lang('WIKI_CATEGORY_ARTICLES_TOTAL', $total),
+			'CATEGORY_SUBCATEGORY_TOTAL'	=> $sub_total ? $this->user->lang('WIKI_CATEGORY_SUBCATEGORIES_TOTAL', $sub_total) : '',
 		));
 	}
 

docs/TODO.md

@@ -23,13 +23,9 @@ Built: `[[Category:Name]]` in an article puts it in a category, a category page
 (`/wiki/Category:Name`) lists the articles in it, and `/wiki/categories` lists them all. See
 the README.
 
-Also built (10/15/2026): categories added by a template, sub-categories, `[[:Category:Name]]`
-links and sort keys, from a stored membership table that a cron task fills after the update.
-
-Not built:
-
-- Paging the sub-categories of a category separately from its articles, and showing how many
-  articles each sub-category holds.
+Also built (10/15/2026): categories added by a template, sub-categories (paged on their own,
+with how many articles each holds), `[[:Category:Name]]` links and sort keys, from a stored
+membership table that a cron task fills after the update. Nothing more is planned here.
 
 ## A wiki-style UI, not just reskinned forum templates
 

language/en/common.php

@@ -177,6 +177,19 @@
 	),
 	'WIKI_CATEGORY_MEMBERS'			=> 'Articles in this category',
 	'WIKI_CATEGORY_SUBCATEGORIES'	=> 'Sub-categories',
+	'WIKI_CATEGORY_SUBCATEGORIES_TOTAL'	=> array(
+		1	=> '1 sub-category',
+		2	=> '%d sub-categories',
+	),
+	'WIKI_CATEGORY_HOLDS_ARTICLES'	=> array(
+		0	=> 'no articles',
+		1	=> '1 article',
+		2	=> '%d articles',
+	),
+	'WIKI_CATEGORY_HOLDS_SUBCATEGORIES'	=> array(
+		1	=> '1 sub-category',
+		2	=> '%d sub-categories',
+	),
 	'WIKI_CATEGORY_EMPTY'			=> 'No article is in this category yet.',
 	'WIKI_CATEGORY_NO_PAGE'			=> 'This category has no description yet.',
 	'WIKI_CATEGORY_WRITE'			=> 'Write one',

styles/prosilver/template/category_members.html

@@ -2,9 +2,31 @@
 <h3>{L_WIKI_CATEGORY_SUBCATEGORIES}</h3>
 <ul class="wiki-subcategories">
 	<!-- BEGIN category_subcategories -->
-	<li><a href="{category_subcategories.U_CATEGORY}"><strong>{category_subcategories.NAME}</strong></a><!-- IF category_subcategories.DESCRIPTION --> &ndash; {category_subcategories.DESCRIPTION}<!-- ENDIF --></li>
+	<li><a href="{category_subcategories.U_CATEGORY}"><strong>{category_subcategories.NAME}</strong></a> <span class="wiki-subcategory-count">({category_subcategories.COUNT})</span><!-- IF category_subcategories.DESCRIPTION --> &ndash; {category_subcategories.DESCRIPTION}<!-- ENDIF --></li>
 	<!-- END category_subcategories -->
 </ul>
+<div class="action-bar">
+	<div class="pagination">
+		{CATEGORY_SUBCATEGORY_TOTAL}
+		<!-- IF .sub_pagination -->
+		<ul>
+		<!-- BEGIN sub_pagination -->
+			<!-- IF sub_pagination.S_IS_PREV -->
+			<li class="arrow previous"><a class="button button-icon-only" href="{sub_pagination.PAGE_URL}" rel="prev" role="button"><i class="icon fa-chevron-{S_CONTENT_FLOW_BEGIN} fa-fw" aria-hidden="true"></i><span class="sr-only">{L_PREVIOUS}</span></a></li>
+			<!-- ELSEIF sub_pagination.S_IS_CURRENT -->
+			<li class="active"><span>{sub_pagination.PAGE_NUMBER}</span></li>
+			<!-- ELSEIF sub_pagination.S_IS_ELLIPSIS -->
+			<li class="ellipsis" role="separator"><span>{L_ELLIPSIS}</span></li>
+			<!-- ELSEIF sub_pagination.S_IS_NEXT -->
+			<li class="arrow next"><a class="button button-icon-only" href="{sub_pagination.PAGE_URL}" rel="next" role="button"><i class="icon fa-chevron-{S_CONTENT_FLOW_END} fa-fw" aria-hidden="true"></i><span class="sr-only">{L_NEXT}</span></a></li>
+			<!-- ELSE -->
+			<li><a class="button" href="{sub_pagination.PAGE_URL}" role="button">{sub_pagination.PAGE_NUMBER}</a></li>
+			<!-- ENDIF -->
+		<!-- END sub_pagination -->
+		</ul>
+		<!-- ENDIF -->
+	</div>
+</div>
 <!-- ENDIF -->
 <h3>{L_WIKI_CATEGORY_MEMBERS}</h3>
 <!-- IF .category_members -->

styles/prosilver/theme/style.css

@@ -331,3 +331,9 @@ form.wiki-start-from p {
 .wiki-buttons .button.wiki-protect-on .icon {
 	color: #bc2a4d;
 }
+
+/* On a category page: how much each sub-category holds */
+.wiki-subcategory-count {
+	opacity: 0.8;
+	font-size: 0.95em;
+}

tests/wiki/category_members_test.php

@@ -84,6 +84,28 @@ public function test_members_sort_by_key_or_title_with_sub_categories_apart()
 		$this->assertSame(array('Fruit' => 4, 'Tropical' => 1), $members->in_use());
 	}
 
+	public function test_counts_give_articles_and_sub_categories_apart()
+	{
+		$members = $this->members(array(
+			'Mango'				=> array('Tropical' => ''),
+			'Apple'				=> array('Tropical' => ''),
+			'Category:Tropical'	=> array('Fruit' => ''),
+			'Zebra'				=> array('Fruit' => ''),
+			'Draft'				=> array('Tropical' => ''),
+		));
+		foreach (array('Mango', 'Apple', 'Category:Tropical', 'Zebra', 'Draft') as $article)
+		{
+			$members->update($article);
+		}
+
+		$this->assertSame(array(
+			'Tropical'	=> array('articles' => 2, 'subcategories' => 0),
+			'Fruit'		=> array('articles' => 1, 'subcategories' => 1),
+			'Empty'		=> array('articles' => 0, 'subcategories' => 0),
+		), $members->counts(array('tropical', 'Fruit', 'Empty')), 'a version that is not live does not count');
+		$this->assertSame(array(), $members->counts(array()));
+	}
+
 	public function test_an_article_that_is_not_live_is_not_listed()
 	{
 		$members = $this->members(array('Draft' => array('Fruit' => '')));

wiki/categories.php

@@ -278,6 +278,17 @@ public function subcategories($category)
 		return $this->category_members->built() ? $this->category_members->members($category)['subcategories'] : array();
 	}
 
+	/**
+	 * How many articles and sub-categories each of these categories holds.
+	 *
+	 * @param array $categories
+	 * @return array Normalised names with 'articles' and 'subcategories' counts
+	 */
+	public function counts(array $categories)
+	{
+		return $this->category_members->counts($categories);
+	}
+
 	/**
 	 * The short description of every category that has a page: the description field of
 	 * the live version of its "Category:Name" article.

wiki/category_members.php

@@ -275,6 +275,37 @@ public static function compare(array $a, array $b)
 		return strnatcasecmp($key_a, $key_b) ?: strcmp($a['article_url'], $b['article_url']);
 	}
 
+	/**
+	 * How many live articles and sub-categories each of these categories holds, read in one
+	 * query, for the counts beside sub-categories.
+	 *
+	 * @param array $categories Category names
+	 * @return array Normalised names with 'articles' and 'subcategories' counts
+	 */
+	public function counts(array $categories)
+	{
+		$names = array_values(array_unique(array_map(array(categories::class, 'normalise'), $categories)));
+		$counts = array_fill_keys($names, array('articles' => 0, 'subcategories' => 0));
+		if (!$names)
+		{
+			return $counts;
+		}
+
+		$sql = 'SELECT m.category, a.article_url
+			FROM ' . $this->member_table . ' m
+			JOIN ' . $this->article_table . ' a ON a.article_url = m.article_url
+			WHERE ' . $this->db->sql_in_set('m.category', $names) . '
+				AND ' . $this->templates->live_where('a', '');
+		$result = $this->db->sql_query($sql);
+		while ($row = $this->db->sql_fetchrow($result))
+		{
+			$counts[$row['category']][strpos($row['article_url'], categories::PREFIX) === 0 ? 'subcategories' : 'articles']++;
+		}
+		$this->db->sql_freeresult($result);
+
+		return $counts;
+	}
+
 	/**
 	 * Every category with a live article in it, and how many (sub-categories included).
 	 *