GraphQL Storefront API call to apply a Discount.

[Kai_Yu]

Im making a private App that applies a discount to the Checkout.

Im have to use the Stroefront API since private Apps cant get

var discountUrl = TestStoreURL + '/api/graphql.json';
        var base64Id = Buffer.from(id.toString()).toString('base64');
        const checkoutQuery = `
        mutation checkoutDiscountCodeApplyV2($discountCode: String!, $checkoutId: ID!) {
            checkoutDiscountCodeApplyV2(discountCode: $discountCode, checkoutId: $checkoutId) {
              checkout {
                id
              }
              checkoutUserErrors {
                code
                field
                message
              }
            }
          }
          
          {
            checkoutId: ` + base64Id + `,
            discountCode: ` + discountCode + `
          }
          `;
        const results = await fetch(discountUrl, {
            method: 'POST', 
            uri: discountUrl,
            headers : {
                'X-Shopify-Storefront-Access-Token' : SHOPIFY_ACCESS_STOREFRONT_TOKEN_TEST,
                'Accept': 'application/json, text/plain, ',
                'Content-Type': 'application/json'
            },
            body : JSON.stringify(checkoutQuery)
          })
          .then(response => response.json())
          .then(json => {
            log.info(json);
          });

permisson for the Checkout scope of the Admin API.

So im trying to use the checkoutDiscountCodeApplyV2 mutation. But im always getting errors: 'Parameter Missing or Invalid'  and no futher information.

Here is the relevant code:

[c10s]

You likely need to pass the variables and query separately when using fetch.

const checkoutQuery = `
    mutation checkoutDiscountCodeApplyV2($discountCode: String!, $checkoutId: ID!) { 
        checkoutDiscountCodeApplyV2(discountCode: $discountCode, checkoutId: $checkoutId) {
            checkout {
                id
            } 
            checkoutUserErrors {
                code
                field
                message
            }
        }
    }
`;

body: JSON.stringify({
    query: checkoutQuery,
    variables: {
        checkoutId: base64Id,
        discountCode
    }
})

[Kai_Yu]

Thanks for your reply I changed my code according to your suggestion and the variables are now send correctly.

Im currently sending the checkoutId as such:

Buffer.from('gid://shopify/Checkout/'+id.toString()).toString('base64');

 But i get the following Error as a response:

{
  code: 'INVALID',
  field: [ 'checkoutId' ],
  message: 'Checkout existiert nicht'
}

And i get the checkout if directly from the ctx.request.body.id.

Do you might know why i cant find the checkout?.

Do i hve to use the Checkout update instead of the Checkout creation webhook?