Field 'cost' doesn't exist on type 'CartLine'

Retired Boards Appdev Custom Storefronts
1

I’m testing gql cart mutations and queries with storefront api.

When I tried fetching ‘cost’ field on type ‘CartLine’, I got error message for the query.

It said

"Field 'cost' doesn't exist on type 'CartLine'"

Not only the cost field, there are other fields that make same error such as ‘discountAllocations’ field on ‘Cart.’

Why does this error occur? And how can I fix this problem?

Below is the code I executed:

const variables = {id: cartId, numCartLines: 10};
const input = {query: queries.CART_CREATE_MUTATION, variables};   

 const response = await fetch("https://thisisneverthat.com/api/graphql", {
        method: "post",
        headers: {
            "Content-Type": "application/json",
            "Accept": "application/json",
            // https://shopify.dev/api/usage/versioning
            "X-Shopify-API-Version": "2023-01",
            "X-Shopify-Storefront-Access-Token": STOREFRONT_ACCESS_TOKEN
        },
        body: JSON.stringify(input)
    });
    const data = await response.json();

Cart Query:

const CART_QUERY = `
  query CartInfo($id: ID!, $numCartLines: Int=250) {
    cart(id: $id) {
      id
      totalQuantity
      discountAllocations {
        discountedAmount {
          amount
          currencyCode
        }
      }
      discountCodes {
        applicable
        code
      }
      lines(first: $numCartLines) {
        edges {
          node {
            id
            quantity
            cost {
              totalAmount {
                amount
                currencyCode
              }
            }
          }
        }
      }
    }
  }
`;

Error message:

{
  errors: [
    {
      message: "Field 'totalQuantity' doesn't exist on type 'Cart'",
      locations: [Array],
      path: [Array],
      extensions: [Object]
    },
    {
      message: "Field 'discountAllocations' doesn't exist on type 'Cart'",
      locations: [Array],
      path: [Array],
      extensions: [Object]
    },
    {
      message: "Field 'cost' doesn't exist on type 'CartLine'",
      locations: [Array],
      path: [Array],
      extensions: [Object]
    }
  ]
}
2

Hi @YeojinJung :waving_hand:

The type and value of the numCartLines variable needs to be distinct, similar to the below:

query ($id: ID!, $numCartLines: Int!){
    cart(id: $id) {
        id
        totalQuantity
        lines (first: $numCartLines) {
            ...

With variables:

{
    "id": "gid://shopify/Cart/1234",
    "numCartLines": 3
}

I’d recommend trying the below CURL request that uses this format:

curl -L -X POST 'https://YOUR_STORE.myshopify.com/api/2023-01/graphql.json' \
-H 'X-Shopify-Storefront-Access-Token: YOUR_TOKEN' \
-H 'Content-Type: application/json' \
--data-raw '{"query":"query ($id: ID!, $numCartLines: Int!){    cart(id: $id) {        id        totalQuantity        lines (first: $numCartLines) {            nodes {                id                cost {                    totalAmount {                        amount                    }                }            }        }        discountCodes {            code        }        discountAllocations {            discountedAmount {                amount            }        }    } }","variables":{"id":"gid://shopify/Cart/776ec9458c9ae3401fe467fdec9239c1","numCartLines":3}}'

Hope that helps!

3

Hello. Thank you for your email.

Thanks to your help, I could resolve the problem.

By the way, I have another question.

I want to fetch a discount title field when fetching type cart line. I want
to figure out what script discounts are applied to line items.

I know that storefront api doesn’t provide a discount title for cart line
items in cart query but for checkout objects.

But is there any solution (like proxy) to fetch discount allocation title
for cart lines?

Thank you. Regards

Yeojin.

4

Glad that worked for you!

As for the discounts at the CartLine level, we can fragment on the CartDiscountAllocation interface to surface the discount titles as shown below.

{
    cart(id:"gid://shopify/Cart/1234") {
        id
        lines (first: 10){
            nodes {
                id
                discountAllocations {
                    discountedAmount {
                        amount
                    }
                    ... Discounts
                }
            }
        }
    }
}

fragment Discounts on CartDiscountAllocation {
    ... on CartCodeDiscountAllocation{
        code
    }
    ... on CartAutomaticDiscountAllocation {
        title
    }
    ... on CartCustomDiscountAllocation {
        title
    }
}

Hope that helps!