Switching to Mobile Templates with OnWebPageInit and OnLoadDocumentObject

Template switching for mobile devices can become messy very quickly in Evolution CMS if you try to do everything in one event. The cleaner pattern from the donor topic split the work into two plugins: one plugin detects the device and marks the request, while the other swaps the template only when the document is loaded from the database.

That separation is what makes the approach durable.

Step 1: mark mobile requests on every page load

global $modx;

$phoneversion = 0;
session_start();

if (isset($_SESSION['phoneversion'])) {
    $phoneversion = $_SESSION['phoneversion'];
} else {
    require_once $_SERVER['DOCUMENT_ROOT'].'/assets/libs/mobiledetect/Mobile_Detect.php';
    $detect = new Mobile_Detect;
    if ($detect->isMobile() && !$detect->isTablet()) {
        $phoneversion = 1;
    }
    $_SESSION['phoneversion'] = $phoneversion;
}

if ($phoneversion == 1) {
    $_GET['mobile'] = 'true';
}

This plugin belongs on OnWebPageInit. Its job is only to classify the request and make the cache vary cleanly between mobile and non-mobile output.

Step 2: swap the template only when the document object is loaded

global $modx;

$templateMap = [4 => 16, 7 => 18, 8 => 19, 9 => 20, 11 => 21, 12 => 22];
$templateId = $modx->documentObject['template'];

if (isset($templateMap[$templateId])) {
    session_start();
    if (!empty($_SESSION['phoneversion'])) {
        $modx->documentObject['template'] = $templateMap[$templateId];
    }
}

This second plugin belongs on OnLoadDocumentObject. Because it runs when the document is loaded from the database, it lets you build separate cached versions per device type without fighting the parser on every hit.

One important caveat

If you split templates this way, make sure the same TVs are available to both the desktop and mobile template sets. Otherwise the switching logic works, but the content model will not.