This is not an officially supported feature in Event Espresso 3.1, but through working with some of our customers we have worked out how to make it happen with some slight modifications. None of the modifications are to the core code of EE, so this should continue to work after upgrading your version of EE. Some of the modifications are to the payment gateway files, and since Paypal is the most popular payment gateway, the initial version of this is to the Paypal gateway only. If other gateways are requested to be modified in a similar way, then we will try to make that happen in a most requested first fashion.
The first thing you need to do is add a custom function.
You can add this code to one of the following:
1 – Your theme’s functions.php file. It may get overwritten the next time you update your theme.
2 – The EE custom files add-on in the custom_functions.php file.
3 – Use this blank plugin to hold the custom functions.
Next, you’ll need to make a slight modification to the payment_overview.php template file, in order to display the amount paid and amount owed on the thank-you page. You’ll want to put the modified template file in uploads/espresso/templates in order to preserve your changes from being overwritten the next time you update EE. You can download the modified file here.
The last part is the gateway specific changes. Like the changes to the template file, you can store the modified gateway files under uploads/espresso/gateways to preserve the changes from being overwritten in an update.
The paypal files that were modified were paypal_vars.php, paypal_ipn.php, and Paypal.php. You have two options for how to get these files. If you are familiar with github, and how to clone a repo, you can use the clone URL on this page to grab all the files in the repo, then copy the paypal folder to your uploads/espresso/gateways folder. If you are not comfortable using git, you can copy your existing paypal folder from plugins/event-espresso/gateways to uploads/espresso/gateways folder. Then use theses links to get the “raw” files and copy them into uploads/espresso/gateways/paypal, overwriting the existing copies. Paypal.php , paypal_vars.php , and paypal_ipn.php.