Third party modules in mailalert on prestashop

Question:

I have a custom module that I'm using on prestashop 1.5.4.1 and I need to show some information on the new_order email. I'm quite new to prestashop and it's the first time I'm messing with it.. I wanna know how I can get the variable of that module and show it on the email template.
I already found where the new_order mail variables are set, but don't know how I can add my new custom variable to it.
Any help will be appreciated. Thanks!
 

Answer:

You should override the PaymentModule class and add your custom variable to the email template.

Copy the validateOrder method from classes/PaymentModule.php
Create override/classes/PaymentModule.php and paste the validateOrder method:

<?php
class PaymentModule extends PaymentModuleCore
{
  //paste validateOrder here
}

Find the following line in validateOrder:

'{delivery_other}' => $delivery->other,

After that line assign your custom variable. For example:

'{delivery_date}' => $myDeliveryDate,

Remove /cache/class_index.php to clear the cache.
Copy order_conf.html and order_conf.txt from mails/en to themes/YOURTHEME/mails/en if they are not already there. This will prevent PrestaShop updates to overwrite your changes.
Add your custom variable to the new order_conf.html and order_conf.txt. For example:

<tr>
  <td align="left">Delivery date: {delivery_date}</td>
</tr>