Add category system to categorize posts (readme)

This commit implements a new category system to categorize posts. Each
category can have an unlimited number of nested children categories. A
single post don't necessarily need to be in a category, but it can.

Each category can have a full content body like posts or pages, so you
have enough space to describe the content of your categories.

Please note that you need to have at least the following MySQL/MariaDB
versions to use the category system, because it uses "WITH RECURSIVE"
database queries, the so-called "Common-Table-Expressions (CTE)".

MariaDB: 10.2.2
MySQL: 8.0

See: https://mariadb.com/kb/en/with/
See: https://dev.mysql.com/doc/refman/8.0/en/with.html

1 files changed, 26 insertions, 1 deletions

diff --git a/theme/admin/html/post/form.php b/theme/admin/html/post/form.php
index 346d6f4..4ae07bd 100644
--- a/theme/admin/html/post/form.php
+++ b/theme/admin/html/post/form.php
@@ -1,3 +1,18 @@
+<?php
+function categorySelectList($category_tree, $selected = NULL, $prefix = '') {
+	foreach($category_tree as $category) {
+		$option = '<option value="%s"%s>%s%s [%d]</option>';
+		$select = ($category['ID'] == $selected) ? ' selected' : '';
+
+		printf($option, $category['ID'], $select, $prefix, escapeHTML($category['NAME']), $category['ID']);
+
+		if(isset($category['CHILDS'])) {
+			# If there are children, call self and pass children array.
+			(__FUNCTION__)($category['CHILDS'], $selected, $prefix.'– ');
+		}
+	}
+}
+?>
 <?php if($FORM['INFO']): ?>
 	<div id="message-list-wrapper">
 		<ul id="message-list">
@@ -16,7 +31,7 @@
 		<label for="form_name">
 			<i class="fa fa-newspaper-o"></i><?=$Language->text('label_name')?></label>
 
-		<div class="form-grid-item first">
+		<div class="form-grid-item">
 			<input id="form_name" name="name" value="<?=escapeHTML($FORM['DATA']['NAME'])?>" />
 		</div>
 
@@ -27,6 +42,16 @@
 			<input id="form_slug" name="slug" value="<?=escapeHTML($FORM['DATA']['SLUG'])?>" />
 		</div>
 
+		<label for="form_category">
+			<i class="fa fa-tag"></i><?=$Language->text('label_category')?></label>
+
+		<div class="form-grid-item">
+			<select id="form_category" name="category">
+				<option value="">[ –– <?=$Language->text('label_category')?> –– ]</option>
+				<?=categorySelectList($FORM['CATEGORY_TREE'], $FORM['DATA']['CATEGORY']);?>
+			</select>
+		</div>
+
 		<label for="form_user">
 			<i class="fa fa-user"></i><?=$Language->text('label_user')?></label>