Silverstripe 4 silvershop optionsetfield customise with two values and date expiration if poss

Question

My client wants to have a location and date on the attributes for SilverShop which is fine. I have done this to allow the two fields to work back end. But trying to combine two values into a dropdown or optionset. PHP is not my strong point and probably is very simple.

so below is the code required to change. So the $location and $thedate are the values that need to be put together ie. London - 24/04/2020.

So at the moment it is working with just location and I cannot workout how to put them together with hyphen in the middle.

   public function getOptionsetField($emptystring = null, $values = null)    
{
    $values = ($values) ? $values : $this->Values()->sort(['Sort' => 'ASC', 'Value' => 'ASC']);

    $location = 'Location';
    $thedate = 'TheDate';

    if ($values->exists()) {
        $field = OptionsetField::create(
            'ProductAttributes[' . $this->ID . ']',
            $this->Name,
            $values->map('ID', $location )
        );
                   return $field;
    }
    return null;
}

Another function I wanted to incorporate was that of not showing the values with dates gone past. So hide past dates. ie expiration. This was the old site code and was wondering if I could incorporate in this code by any chance.

public function hasExpired() {
return (strtotime($this->TheDate) > time());
}

Thanks