function react_post($post_id, $reaction_name) {
        if ($this->session->userdata('teacher_login') != 1 || $this->session->userdata('teacher_type') != 1)
          redirect(base_url(), 'refresh');

        $check = $this->db->get_where('reactions', array(
          'post_id'   => $post_id,
          'user_id'   => $this->session->userdata('teacher_id'),
          'user_type' => 'teacher',
        ))->row();

        $data['reaction_name'] = $reaction_name;

        if(empty($check)) {
          $data['post_id']       = $post_id;
          $data['user_type']     = 'teacher';
          $data['user_id']       = $this->session->userdata('teacher_id');

          $this->db->insert('reactions', $data);
        } else {
          $this->db->where('id', $check->id);
          $this->db->update('reactions', $data);
        }

        return true;
      }