A gem (Rails 3 engine) that lets you generate coupon codes based on both a numeric (i.e. 113-22-3) and alpha mask (AA-AA-AA) through a web interface.
Coupons can be tied to up to 2 categories. For instance, a coupon can apply to both “product” and “tax”. Each category has a decimal amount, and a percentage that it can discount. The fixed amounts are applied first, then the percentage is applied.
After installing them gem, you can visit /coupons to generate coupons.
You can generate multiple coupons at a time. Each coupon can be set to be able to be redeemed X times
There are 2 methods that you can call. Coupons#apply which takes in array of {product : price } pairs. It will return a hash with the savings for each product, total savings, and grand total.
This is returned in JSON form (typically called from an AJAX call) and useful info is displayed to the user. The test/dummy has an example application which shows how it can be used.
There is the Coupons#redeem method which takes a coupon, as well as some metadata which is simply stored.
Both #redeem and #apply will throw the appropriate exception if there is a problem.