Email subject does not respect user's preferred language in abandoned cart emails

[romainpoirier]

Describe the bug

The email subject line for abandoned cart reminders does not respect the user's preferred language when it is set using a custom field. While I am able to dynamically set the email's content language using the Carts::EVENT_BEFORE_MAIL_SEND event, the subject line always defaults to the primary site language.

Context:

In my project, users have a custom field preferredLanguage, which specifies their preferred communication language. Using the following event listener, I dynamically set the email content to match this preference:

Event::on(
    Carts::class,
    Carts::EVENT_BEFORE_MAIL_SEND,
    function (BeforeMailSend $event) {
        $order = $event->order;
        $message = $event->message;

        // Retrieve the user associated with the order
        $user = User::find()->id($order->customerId)->one();

        if ($user) {
            // Get the user's preferred language (custom field)
            $preferredLanguage = $user->getFieldValue('preferredLanguage');

            // If no preferred language, fallback to the primary site language
            if (!$preferredLanguage) {
                $preferredLanguage = Craft::$app->sites->primarySite->language;
            }

            // Set the system language
            Craft::$app->language = $preferredLanguage;

            // Set the email message language
            $message->language = Localization::normalizeLanguage($preferredLanguage);
        }
    }
);

While this correctly updates the language for the email content, the subject lines configured in the plugin, such as:

'firstReminderSubject' => Craft::t('site', 'Votre panier vous attend'),
'secondReminderSubject' => Craft::t('site', 'Votre panier vous attend toujours'),

always fall back to the site's default language.

Expected:

The email subject should respect the user's preferred language.

Actual:

The email subject defaults to the site's primary language, regardless of the user's preference.

Additional Notes:

I suspect this behavior is related to how the subject is defined in the sendMail function of the plugin. It does not appear to take into account the dynamically set Craft::$app->language or the $message->language value.

Steps to reproduce

1. Configure a Craft CMS project with the verbb/abandoned-cart plugin.
2. Add a custom field preferredLanguage to the User model and set values for different users (e.g., "fr", "en").
3. Create translations for email subjects in translations/{language}/site.php.
4. Use the Carts::EVENT_BEFORE_MAIL_SEND event to set the email content's language dynamically based on the user's preferredLanguage field.
5. Trigger an abandoned cart email for a user whose preferred language is different from the site's default language.

Craft CMS version

5.5.10

Plugin version

4.0.4

Multi-site?

Yes

Additional context

No response

[engram-design]

That's very likely correct, as we're just using these values from the plugin settings. I think we can sort that out.

[romainpoirier]

Thank you! In the meantime, while waiting for an improvement on this, is there a workaround available today to ensure that the subject of the sent email is in the user's preferred language?

[engram-design]

I don't think there's a quick fix for this that's a DIY solution, sorry!

[romainpoirier]

Wouldn't it be possible to modify the subject on the fly using verbb\abandonedcart\services\Carts\Carts::EVENT_BEFORE_MAIL_SEND to work around this?

Example:

Event::on(
    Carts::class,
    Carts::EVENT_BEFORE_MAIL_SEND,
    function (BeforeMailSend $event) {
        $message = $event->message;
        $message->subject = 'Custom translated text from user preferred language';
    }
);

[engram-design]

Ah, you know I did forget about that event. You'd be right. I was thinking you could only use the native Craft EVENT_BEFORE_MAIL_SEND which isn't ideal, as there's no way to easily tell in that event what an email from Abandoned Carts is.

Thanks for raising that. Haven't tested it specifically, but I believe that should work for now?