Best way Implement "referral links" in Django

Intro

I am working on an e-commerce website. And we want to add a feature where a user can refer others via a custom link e.g.:

http://exa开发者_开发问答mple.com/a1t2312 or http://example.com/?ref=a1t2312 (a1t231 being the referral code).

A user following such a link, will navigate a few pages on the site. And if he reached the 'buy' page and purchases something - the original referrer will get a discount.

The question is:

What is the best method to track the referral code? Put it in the user's cookies? Stick it somehow into the session? Other method?

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I would definitely use cookies, as it is the easiest (but not foolproof, though). Sessions are by site, so that won't work, unless the receiving site has some code to handle the user.

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All methods mentioned by you are OK. If I were you I would consider using sessions because it is more natural to me.

disclaimer: session has some limitations when you want to build application ready for heavy-load. For complicated demployment scenarios avoiding sessions might be a good choice.