How can I always display subcategories? I want this module on the left showing always the same - all parent and their children categories..
In the file catalog\controller\module\category.php, replace the following:
if ($category_id == $result['category_id']) {
$children = $this->getCategories($result['category_id'], $new_path);
}
...with:
//if ($category_id == $result['category_id']) {
$children = $this->getCategories($result['category_id'], $new_path);
//}
Source: http://forum.opencart.com/viewtopic.php?f=20&t=3128&p=25921&#p25921
For Opencart 2 this is the solution
OpenCart 2: Show all subcategories in category module by default (php)