Odoo doesn’t natively limit how many different variants of a product can be added to the cart, but you can achieve this with a custom module or by using website sale hooks.

Here’s how you can approach it:

1. Custom Python Logic
   • Override the website_sale.cart_update_json() method.
   • Add a condition to check how many different variants of the course are already in the cart.
   • If it exceeds the limit (e.g., 1), block the addition and return a warning.
2. Alternative: Attribute Filtering
   • If you only want to show limited attribute combinations, configure those under: Sales → Products → Attributes → Values
   • Or use the “Optional Products” feature in the Sales tab to guide user selection.
3. UI Alert (Optional)
   • Use JavaScript to show a message when a user tries to add more than one course variant.

At Wan Buffer Services, we’ve helped many eLearning businesses restrict product configurations and checkout behavior based on business rules.