[Cart Operations] Manage Cart Items

[misha-kotov]

As a Magento developer, I need to manipulate the shopping cart via GraphQL so that I can build basic ecommerce experiences for shoppers on the front-end using only GraphQL.

GraphQL needs to provide sufficient mutations (ways to create/update/delete data) for a developer to build out the storefront checkout experience for a shopper.

Use cases:

• Both guest and registered shoppers can add new items to cart
• Both guest and registered shoppers can update item qty in cart
• Both guest and registered shoppers can remove items from cart
• Both guest and registered shoppers can update the configuration (for a configurable product) or quantity of a previously added configurable product in cart
  • Edit Item link > Product page > Update configuration or qty > Update Cart

Acceptance criteria:

• Cart operations should be useable in both standard Cart and mini-cart
• GraphQL provides the following mutations:
  • addCartItems
  • updateCartItems
  • removeCartItems
• updateCartItems mutation allows the cart item quantity to be updated in a shopper's cart
• All product types are supported in a modular way (e.g. configurable-related schema and resolvers must be declared in ConfigurableProductGraphQl module and the rest of the system should still work if this module is disabled)
• Depending on token in Authorization header (if any), customer or guest service contract should be used
• Changes are covered with web API functional tests. See \Magento\GraphQl\TestModule\GraphQlMutationTest::testMutation as an example.

Proposed schema

My Account area impacted:

• Cart
• Minicart

[masodu]

@misha-kotov a general comment is that normally cart operations are based on a single product selection. AFAICS I am not sure about the use case to add/update more items at the same time.

[masodu]

@misha-kotov I am not sure about current status of magento cart functionalities but in practice we could have a cart with 2 different cart items having the same sku. A simple use case to visualise this is a promotion with a text like By one and get one for free. Again I am not sure how this is (if) implemented in magento but for a promotion like that the cart could have two cart items, with same sku, where the price for one of the cart items is 0. For this kind of use cases I think it is much safer to modify a cart item based on its internal id.

[masodu]

@misha-kotov how would be possible to remove just one cart item?

[misha-kotov]

@masodu updated the description, though I'm not sure where I had described the use case of updating multiple items at the same time. Agreed it should likely be one at a time.
Thanks for pointing out the use case of multiple line items with the same sku. Good scenario to consider.
Not sure if I understand your last question correctly, but you can remove one item at a time from your cart like so:

[masodu]

@misha-kotov my previous comments are based on the following spec:
type Mutation {
carttemsAdd(cartId: String!, items: [CartItemInput!]!): Cart
cartItemsUpdate(cartId: String!, items: [CartItemInput!]!): Cart
cartItemsRemove(cartId: String!): Cart
}
IIUC the cartItemsRemove has as input only the cartId so that's why I wasn't sure how an item can be removed from cart.

A simpler definition could be:
type Mutation {
cartItemAdd(cartId: String!, sku String!, quantity Float!): Cart
cartItemUpdate(cartId: String!, itemId String!, quantity Float!): Cart
cartItemRemove(cartId: String!, itemId String!): Cart
}

Btw what is the scope of the options in cart mutations?

[mhaack]

@misha-kotov the type Cart & type CartItem we need to make sure this is not an 1:1 mapping of the REST api. A few comments on that.

type Cart should additionally contain all relevant information of an entire cart, like:

• all relevant price & cost information like totals, tax, discounts, costs for payment or shipping
• should have a discount attribute (array) to indicate applied discounts for cart or shipping discounts
• should have a coupon/voucher attribute (array) which contains applied coupons

Related to type CartItem:

• only one price is not enough, price should be a list to support multiple prices like item price, discounts, strike price, unit price of product, net/gross, etc.
• should have a discount attribute to indicate applied discounts
• qty: Float not int? If this is to support cart items like "0.5kg of meat"? If yes then I think the unit is missing.
• price: Money money is not defined, I guess that already exists?
• it should be possible to "expand" the product of related to a cart entry to get all product attributes (description, assets, ...) needed to render a cart view without additional calls

[paliarush]

@mhaack thanks for the feedback!

We can design schema of Cart as we think makes the most sense. REST representation served as a starting point and now we can discuss and evolve the schema as needed.

type Cart:

• It will contain all fields relevant to cart, they will be added in scope of other tasks. Right now there is a comment about that in type declaration

type CartItem:

• We'll think what price types should be available and update proposed schema
• Magento allows quantity to be float, it is configurable on product level as far as I remember
• Money already exists and is used within ProductInterface
• Regarding "expand" makes sense, we'll see how to represent it taking into account different product types