Drupal: How to limit the filtration of the view to the exposed filter even if there is a contextual filter set?

In one of my Drupal websites, I had to set a contextual filter on a view based on a parameter which is passed through a link. The view itself has an exposed filter and the client didn't want the results in the view to be limited to the contextual filter value. Instead, he wanted the exposed filters to be the only method of filtration once used.

To be able to overcome this problem and with the help of a trick I knew about through Drupal forums, I had to add a validation criteria for my contextual filter.

I choosed PHP code as the validator and added the following PHP code:

if(!isset($_GET['field_center_nid'])) {
  return TRUE;
}

Finally, I have set the action to take if the filter value does not validate to display all results for the specified field. This way, as long as the "field_center_nid" filter exists in the URL, the contextual filter will not validate.