Background:
We use a product discount function for things like volume discounts - for example:
Buy 2 and get 10% off
We've set it up in this case to work in multiples of 2. So if a customer adds 3 of that item to cart, 2 will be discounted and 1 will be the original price and will be split into it's own line item.
Issue:
When the non-discounted item is removed from cart using the storefront API the discounted items are also removed, even though they have a different line ID (line ID is used to remove a cart line via the api).
Some more detail:
Cart lines before attempting to removing the first one
[
// Non-discounted line
{
"id": "gid://shopify/CartLine/ddd73847-ee2f-4a6d-a9ab-e8dce2832627?cart=Z2NwLXVzLWNlbnRyYWwxOjAxSE00WDI1M0JRMUNaNlBIMk03VDBaRDRZ",
"quantity": 1,
...
},
// Discounted lines - different line ID but share the same variant ID
{
"id": "gid://shopify/CartLine/1db25861-a954-4a0f-8aa6-3ee711eba960?cart=Z2NwLXVzLWNlbnRyYWwxOjAxSE00WDI1M0JRMUNaNlBIMk03VDBaRDRZ",
"quantity": 2,
...
}
]
Payload of removeCartLines mutation, clearly showing the lineID to be removed in the variables object
{
"query": "\n mutation removeCartLines($cartId: ID!, $lineIds: [ID!]!) {\n cartLinesRemove(cartId: $cartId, lineIds: $lineIds) {\n userErrors {\n code\n field\n message\n }\n cart {\n ...cartFields\n }\n }\n }\n \n fragment cartFields on Cart {\n id\n checkoutUrl\n cost {\n subtotal: subtotalAmount {\n amount\n }\n total: totalAmount {\n amount\n }\n }\n discounts: discountAllocations {\n discountedAmount {\n amount\n }\n }\n note\n totalQuantity\n lines(first: 200) {\n edges {\n node {\n id\n attributes {\n key\n value\n }\n cost {\n price: amountPerQuantity {\n amount\n }\n compareAt: compareAtAmountPerQuantity {\n amount\n }\n subtotal: subtotalAmount {\n amount\n }\n total: totalAmount {\n amount\n }\n }\n discounts: discountAllocations {\n discountedAmount {\n amount\n }\n ... on CartAutomaticDiscountAllocation {\n title\n }\n ... on CartCodeDiscountAllocation {\n code\n }\n ... on CartCustomDiscountAllocation {\n title\n }\n }\n merchandise {\n ... on ProductVariant {\n ...variantFields\n }\n }\n quantity\n }\n }\n }\n }\n \n fragment variantFields on ProductVariant {\n availableForSale\n id\n compareAt: compareAtPriceV2 {\n amount\n }\n image {\n altText\n originalSrc\n transformedSrc(maxHeight: 96, maxWidth: 96, crop: CENTER)\n }\n product {\n handle\n id\n images(first: 1) {\n edges {\n node {\n originalSrc\n altText\n }\n }\n }\n ageRestricted: metafield(key: \"age_verification_required\", namespace: \"global\") {\n value\n }\n productType\n tags\n title\n vendor\n }\n price: priceV2 {\n amount\n }\n quantityAvailable\n selectedOptions {\n name\n value\n }\n sku\n title\n }\n\n\n",
"variables": {
"cartId": "gid://shopify/Cart/Z2NwLXVzLWNlbnRyYWwxOjAxSE00WDI1M0JRMUNaNlBIMk03VDBaRDRZ",
"lineIds": [
"gid://shopify/CartLine/ddd73847-ee2f-4a6d-a9ab-e8dce2832627?cart=Z2NwLXVzLWNlbnRyYWwxOjAxSE00WDI1M0JRMUNaNlBIMk03VDBaRDRZ"
]
}
}
Result is both lines being removed that share the same variant ID.
