How to create a coupon that only applies if the cart line has an attribute MagicDiscount

Retired Boards Appdev Customers Discounts And Orders
1

Hello,

Is it possible to apply a coupon to a cart line product variant that is only valid if there’s a cart line attribute “Magic Discount”?

Maybe there’s a better way to achieve what I want:
I have an app with an App theme extension that allows users to set their own price. the extension creates a form where users submit their price, upon submission I want to adjust the price of the product variant to the user set price. Since price cannot be updated during checkout process, I thought I would generate a discount and apply it to the cart line.

I need to ensure these coupon codes generated to adjust price to the user price are only used in the context of my app.

I would appreciate any guidance to approach the problem the right way.

Thank you!

2

This is as far as I got, I created a discount function, on the run.graphql I added this:

query RunInput {
  cart {
    lines {
      id
      merchandise {
        ... on ProductVariant {
          id
          title
        }
      }
      attribute (key: "MagicDiscount"){
            key
            value
          }
      cost {
        totalAmount {
          amount
          currencyCode
        }
      }
      quantity
    }
  }
}

On the run.js I have the control to see if

function hasValidMagicDiscount(line) {
  return (
    line.attribute &&
    line.attribute.key === "MagicDiscount" &&
    line.attribute.value !== undefined &&
    line.attribute.value !== null &&
    line.merchandise &&
    line.merchandise.__typename === "ProductVariant" &&
    line.merchandise.id !== undefined &&
    line.merchandise.id !== null
  );
}

// The configured entrypoint for the 'purchase.product-discount.run' extension target
/**
*  {RunInput} input
* @returns {FunctionRunResult}
*/
export function run(input) {
  const discounts = input.cart.lines
    // Filter lines that have the hasValidMagicDiscount attribute
    .filter(line => hasValidMagicDiscount(line))
    .map(line => {
      const discountAmount = 10;
        return {
          targets: [
            {
              productVariant: {
                id: line.merchandise.id
              }
            }
          ],
          value: {
            fixedAmount: {
              amount: discountAmount,
              currencyCode: line.cost.totalAmount.currencyCode
            }
          }
        };
  if (!discounts.length) {
    // You can use STDERR for debug logs in your function
    console.error("No cart lines qualify for the BargainSDK discount.");
    return EMPTY_DISCOUNT;
  }

  // The /shopify_function package applies JSON.stringify() to your function result
  // and writes it to STDOUT
  return {
    discounts: discounts,
    discountApplicationStrategy: DiscountApplicationStrategy.First
  };
};

Unfortunately I get this on the debug:

{
  "cart": {
    "lines": [
      {
        "id": "gid://shopify/CartLine/0",
        "attribute": null,
        "cost": {
          "totalAmount": {
            "amount": "749.95",
            "currencyCode": "EUR"
          }
        },
        "quantity": 1
      }
    ]
  }
}

I don’t understand where is the error since I know for a fact the attribute MagicDiscount is being passed to the cartline because the cart is created programmatically with these attributes:

const query = `
        mutation {
            cartCreate(
                input: {
                    lines: [
                    {
                        merchandiseId: "gid://shopify/ProductVariant/${variantId}",
                        quantity: ${quantity},
                        attributes: [
                        {
                            key: "MagicDiscount",
                            value: "${discount}"
                        }
                        ]
                    }
                    ]
                }
            ) {
                cart {
                id
                checkoutUrl
                lines(first: 5) {
                    edges {
                    node {
                        id
                        quantity
                        merchandise {
                        ... on ProductVariant {
                            id
                            title
                        }
                        }
                    }
                    }
                }
                }
            }
            }
        `;
3

Mistery solved, it was a typo on the attribute name.