Built-in :date output modifier versus custom PHP output modifier for MODX Revolution timestamps

Answer

No. The built-in :date output modifier in MODX Revolution does not produce consistent output across servers with different PHP timezone settings. It calls PHP's strftime(), whose behavior depends on the server's locale, timezone, and operating-system implementation. Even when the MODX system setting date_timezone is set, strftime() remains sensitive to platform differences—historically between Windows and Unix-like systems—and to locale configuration.

If your only requirement is a fixed date format and you need that format to be identical across multiple servers or containers, a custom output modifier is preferred. A snippet using DateTime or DateTimeImmutable with an explicit timezone and a format string such as 'Y-m-d H:i:s' is portable, because DateTime::format() uses a documented, consistent set of format characters rather than strftime()'s platform-dependent specifiers. The built-in :date is reasonable only for a single-server deployment where the PHP timezone, locale, and OS are fully controlled.

Caching and empty timestamps

Tag caching does not change whether an empty timestamp reaches the modifier. Both cached tags ([[*publishedon:date=%Y-%m-%d]]) and uncached tags ([[!*publishedon:date=%Y-%m-%d]]) resolve the resource field and pass the value to the output modifier at parse time. The only difference is when the modifier runs: once when the cache is written, or on every request for uncached tags. If publishedon is zero or null, strftime() may still receive that value and return an empty string or a fallback such as the Unix epoch, depending on the format string and PHP version.

Recommended approach

1. Create a snippet named, for example, formatDate.
2. Use explicit timezone and format logic inside the snippet.
3. Invoke it in the template as [[*publishedon:formatDate]].
4. Test with a known timestamp and toggle the PHP timezone to confirm the output does not shift.
5. Explicitly handle a zero or empty input in the snippet so you do not emit an unintended epoch date.

Example snippet logic

<?php
if (empty($input)) {
    return '';
}
$dt = new DateTime('@' . $input);
$dt->setTimezone(new DateTimeZone('UTC'));
return $dt->format('Y-m-d H:i:s');
?>

Verification and version caution

Because strftime() is deprecated as of PHP 8.1, MODX 3.x may handle the :date modifier differently than MODX 2.x—potentially through a polyfill or an internal switch to DateTime. That behavior is version-dependent and should be verified in your specific stack before relying on it. To confirm locally, create a resource with a known publishedon value, render both [[*publishedon:date=%Y-%m-%d %H:%M:%S]] and your custom modifier, then change the PHP timezone and reload.

Missing diagnostic detail: Which MODX major version and PHP version are you running? The answer determines whether the built-in :date modifier is deprecated or internally rewritten, which changes the recommendation.