/**
* Sends Last-Modified and checks If-Modified-Since for a match (if so, terminates and sends a 304 Not Modified status code). Uses the given timestamp as base for calculation. If it is an object or a query, the updated-at field of the object (or the newest item that matches the query) is used. You can call this method twice if you created a new cache file and don’t have any other timestamp. It will only output the headers once.
* @param $mTimestamp The last-modified date to send. Can be one of the following:
* • A UNIX timestamp as an integer
* • A string to be parsed into a date using strtotime
* • A DateTime object
* • A Propel database object whose updated_at timestamp will be used
* • A Propel query that will find the object most recently updated and use its updated_at timestamp
*/
public static function sendLastModifiedAndCheckModifiedSince($mTimestamp)
{
if (self::$LAST_MODIFIED_SENT) {
return;
}
if ($mTimestamp instanceof BaseObject) {
$mTimestamp = $mTimestamp->getUpdatedAtTimestamp();
}
if ($mTimestamp instanceof ModelCriteria) {
$mTimestamp = $mTimestamp->findMostRecentUpdate();
}
if (is_string($mTimestamp)) {
$mTimestamp = strtotime($mTimestamp);
}
if ($mTimestamp === null) {
return;
}
if ($mTimestamp instanceof DateTime) {
$mTimestamp = clone $mTimestamp;
$mTimestamp->setTimezone(new DateTimeZone('UTC'));
} else {
$mTimestamp = new DateTime("@{$mTimestamp}");
}
header("Last-Modified: " . $mTimestamp->format(self::DATE_RFC2616));
self::$LAST_MODIFIED_SENT = true;
if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE'])) {
$oSinceDate = DateTime::createFromFormat(self::DATE_RFC2616, $_SERVER['HTTP_IF_MODIFIED_SINCE'], new DateTimeZone('UTC'));
if ($oSinceDate->getTimestamp() >= $mTimestamp->getTimestamp()) {
self::sendHTTPStatusCode(304, 'Not Modified');
header('Content-Length: 0');
exit;
}
}
}