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, 10 insertions, 0 deletions

diff --git a/core/namespace/Application.php b/core/namespace/Application.php
index 2329253..5690841 100644
--- a/core/namespace/Application.php
+++ b/core/namespace/Application.php
@@ -141,6 +141,13 @@ class Application {
 	}
 
 	#===============================================================================
+	# Return absolute category URL
+	#===============================================================================
+	public static function getCategoryURL($more = ''): string {
+		return self::getURL(self::get('CATEGORY.DIRECTORY')."/{$more}");
+	}
+
+	#===============================================================================
 	# Return absolute post URL
 	#===============================================================================
 	public static function getPostURL($more = ''): string {
@@ -188,6 +195,9 @@ class Application {
 	#===============================================================================
 	public static function getEntityURL(EntityInterface $Entity) {
 		switch($class = get_class($Entity)) {
+			case 'ORM\Entities\Category':
+				$attr = self::get('CATEGORY.SLUG_URLS') ? 'slug' : 'id';
+				return self::getCategoryURL($Entity->get($attr).'/');
 			case 'ORM\Entities\Page':
 				$attr = self::get('PAGE.SLUG_URLS') ? 'slug' : 'id';
 				return self::getPageURL($Entity->get($attr).'/');