I believe these are the best steps of implementing the changes to WooCommerce needed to add the ability for customers to update the variations of products that have already been added to the cart. These steps represent individual smaller pull requests per @mikejolley.
You can see all of the changes together by comparing here.
- Add new files. Don't touch core at all. The
cart-update-variation.js
file takes the available varitions that are loaded withwp_localize_script()
and compares them to the selected values of the attribute select fields. When a match is found the it will update a hidden field with variation id. This field is used when updating the cart. This vsariation id update is