/**
* @param $datetime
* @return string
* @throws EE_Error
*/
private function _convert_from_string_value_to_utc_unix_timestamp($datetime)
{
//create a new datetime object using the given string and timezone
$this->_set_date_obj($datetime, $this->_timezone);
if (!$this->_date instanceof DateTime && !$this->_nullable) {
throw new EE_Error(__('Something went wrong with setting the date/time. Likely, either there is an invalid datetime string or an invalid timezone string being used.', 'event_espresso'));
}
$this->_date->setTimezone(EE_Datetime_Field::get_UTC_DateTimeZone());
return $this->_date->format('U');
}
