categories display problem show all categories

You have to add a where clause to your model like

PHP Code:

public function get_categories($category_name = false, $order_by = null, $sort = 'DESC', $limit = null, $offset = 0) {
        $this->db->select('a.*, c.name as category_name');
        $this->db->from('articles as a');
        $this->db->join('categories AS c', 'a.category_id = c.id ','LEFT');
        if ($category_name)
        {
            $this->db->where('categories.name', $category_name);
        }
        if($limit != null) {
            $this->db->limit($limit, $offset);
        }
        if($order_by != null) {
            $this->db->order_by($order_by, $sort);
        }
        $query = $this->db->get();
        return $query->result();
} 


Or you check the where with the category id ..