Zero price item on expand operation

Functions
1

Hi everyone, maybe someone has run into the issue of setting a zero price for an item added through a Cart Transform function’s expand operation.

I’m writing a Cart Transform function. At this stage, the logic is simple: I add a wrapper product to the cart with a JSON attribute that includes both the variant id of product P1 (with a non-zero price) and the variant id of gift product P2 (with a zero price).

I noticed that in this case, add.js returns a 422 error:

{"status":422,"message":"Cart Error","description":"The bundle product 'Wrapper' cannot be added to the cart."}

- but really the wrapper product still gets added to the cart, and the CTA function runs without errors. The output is correct, and the cart shows the right price.

Input:

{
  "cart": {
    "lines": [
      {
        "id": "gid://shopify/CartLine/68f8af6e-665b-4522-b25f-e3cd33209f30",
        "quantity": 1,
        "offer": {
          "value": "{\"offer_variant_id\":\"gid://shopify/ProductVariant/42526948458563\",\"offer_name\":\"Test\",\"offer_id\":1,\"items\":[{\"variant_id\":42183658176579,\"price\":90}],\"gifts\":[{\"variant_id\":42183657914435}]}"
        },
        "merchandise": {
          "__typename": "ProductVariant",
          "id": "gid://shopify/ProductVariant/42526948458563",
          "title": null,
          "product": {
            "title": "Wrapper",
            "handle": "wrapper"
          }
        }
      }
    ]
  }
}

Output:

{
  "operations": [
    {
      "lineExpand": {
        "cartLineId": "gid://shopify/CartLine/68f8af6e-665b-4522-b25f-e3cd33209f30",
        "expandedCartItems": [
          {
            "merchandiseId": "gid://shopify/ProductVariant/42183658176579",
            "price": {
              "adjustment": {
                "fixedPricePerUnit": {
                  "amount": "90"
                }
              }
            },
            "quantity": 1
          },
          {
            "merchandiseId": "gid://shopify/ProductVariant/42183657914435",
            "price": {
              "adjustment": {
                "fixedPricePerUnit": {
                  "amount": "0.0"
                }
              }
            },
            "quantity": 1
          }
        ],
        "image": null,
        "price": null,
        "title": "Wrapper"
      }
    }
  ]
}

At checkout, I see my wrapper product containing both P1 and P2, but then I encounter an error.

image
image1539×547 40.1 KB

If I set the price > 0 for the gift product, then the add.js request returns 200 and checkout works fine.

What really confuses me is that the Cart Transform function itself doesn’t report any errors. I tested the function, got the correct response, and didn’t expect issues at checkout.

I haven’t found anything in the docs saying that item prices can’t be set to zero.

So I’d like to understand: is this a Shopify bug, or my issue and is there some required workaround for setting a zero price?

2

Hi @Siarhei_Shyshko,

Thanks for reporting this issue! We’ve confirmed this is a platform limitation with Cart Transform expand operations and zero-price items.

We’ve created an internal issue to track this and will add it to our roadmap. In the meantime, you can use a minimal price like “0.01” instead of “0.0” as a workaround.

Appreciate you bringing this to our attention!

3

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