Updating TV Values from Shopkeeper During Frontend Events

Sometimes ecommerce logic spills into content fields. The original Shopkeeper topic behind this article showed how a frontend event plugin could inspect purchase data and write changes back into a TV.

Typical Event

if ($e->name == 'OnSHKFrontendInit') {
    if (isset($_SESSION['purchases'])) {
        $purchases = unserialize($_SESSION['purchases']);
        foreach ($purchases as $value) {
            // inspect product ID, count, price
        }
    }
}

Typical TV Update

$query = "UPDATE `modx_site_tmplvar_contentvalues`
SET value = value + 1
WHERE tmplvarid = 46 AND contentid = " . $value[0];

This kind of pattern can work, but it should be used carefully. Once business counters or inventory-like values are updated through frontend hooks, concurrency and data integrity become real concerns.

The rule of thumb is simple: if a TV is becoming transactional state, treat it more like application data and less like presentation metadata.