Guide 08 · Developer docs

A Core dna store is a set of records and an API that moves a purchase from cart to order: products described in every language and priced in every currency the store sells in, a cart, a checkout that becomes an order, invoices, payments, tax and shipping. The site builds the storefront on top: the cart and checkout pages, their scripts, and the customer emails.

L2–L3

Unit 02 of 08 3 pages

Carts, cookies and the cache

Updated 23/10/2026 01:46

The cart record and the cookie that finds it, changing a cart through the API, and keeping the cart off cached pages. For the developer building add-to-cart, the cart page and the header's cart icon.

Almost every cart issue on a site comes from one of two things: the cookie that finds the cart, or a cached page that shows one visitor's cart to everyone. Read The cart record and its cookie first; its diagnosis list answers "my cart emptied". Changing the cart has the requests, with the refusals that answer 200, the messages that explain them and the limits on item attributes.

Read The cart count on a cached page before building a site header: it is a short page with one rule, and the rule prevents the most common cart complaint of all.

In this unit

Read in order

01 The cart record and its cookie A cart is a database record found through a cookie, not session data. What it holds and how long it lives, the cookie's attributes and the paths that lose a cart, what happens to a guest cart when the shopper signs in, the restore link, and abandoned carts. 02 Changing the cart Adding, updating and removing items, and discount codes, through the cart API: the requests with real responses, the business refusals that answer 200, the messages that report them, the limits on item attributes, and the cart page that shows it all. 03 The cart count on a cached page A page the page cache stores cannot carry one visitor's cart. The rule, the two things that go wrong when a header prints the cart, and the pattern that fixes it: a placeholder in the template and a count filled in by the browser from the cart API.

Objects ReferenceGenerated from the platform, so it is always current

API ReferenceEvery REST endpoint, in cURL, PHP, Python and JavaScript

Carts, cookies and the cache

In this unit