Call to undefined method Tools::displayPrice() in PrestaShop 9

What happened#

Tools::displayPrice() turned a number into a price with the currency sign, for example 12.5 into €12.50. PrestaShop moved price formatting to its localization component years ago and kept the old method as a shortcut. In PrestaShop 9.0 the shortcut is gone.

Code that still calls it now ends with a fatal error. If the call runs on every page (a header block, a product list, a cart summary), the whole store can show a blank page or error 500. If it runs only in one place, only that place breaks, for example a module's settings page or one email.

The fix#

Format the price through the current locale instead:

// Before (PrestaShop 1.7 and 8)
$formatted = Tools::displayPrice($price, $currency);

// After (works in 1.7.6+, 8 and 9)
$context = Context::getContext();
$formatted = $context->getCurrentLocale()->formatPrice($price, $context->currency->iso_code);

If the old call passed a currency, use that currency's ISO code:

• a Currency object: $currency->iso_code
• a currency ID: Currency::getIsoCodeById((int) $idCurrency)

formatPrice() follows the store's language settings, so the result matches the prices PrestaShop shows elsewhere.

In templates#

Front office templates should not format prices themselves. PrestaShop's presenters already pass formatted prices to the theme (for example {$product.price}), so a template that needs a price should receive it ready from the PHP side. The {displayPrice} Smarty function exists only in the back office, in every version, and so does the 1.6-era {convertPrice} tag: in a front office template both stop with unknown tag. For an amount the module calculates itself, such as a voucher or a fee, format it in the hook with formatPrice() and assign the ready string to the template.

Where else it hides#

Tools::displayPrice() is rarely alone. A module written in the same period often also uses Tools::displayNumber(), Tools::jsonEncode() or ajaxDie(), all removed in PrestaShop 8 or 9. Search the whole module folder, the theme and the override/ folder, not only the file named in the error:

grep -rn "displayPrice\|displayNumber" modules/ themes/ override/

Keep in mind that third-party modules lose your edits at their next update. If the author has a PrestaShop 9 version, install that instead.