Server-side price check?

Question

WordPress

Hi all.

There is a custom checkout form, where the price changes depending on the selected options (number of people, nights, etc.) and the whole thing goes to the payment via ajax and then written to the database.
How to protect yourself from data spoofing on the user side?
Do I understand correctly that you need to recalculate the price in the php callback function based on the initial data (in fact, a double calculator from the front), check with what came from the POST request and then send it to the payment?

Answer 1

At the front, the calculation should be for reference, all calculations that are important must be done on the server side and not on the client