Line Item Properties returning null in cart transform function on specific store

Functions
1

We have a Shopify app that merges products using a cart transform function. The app works correctly on multiple stores, but on one specific store, all line item properties come back as null when accessed inside the transform function.

  • In the cart object (logged), line item properties are present and populated
  • Inside the cart transform function, the same properties return null
  • The issue is isolated to one store — identical code works on all other stores

Extension INPUT:


      {
  "cart": {
    "lines": [
      {
        "id": "gid:\/\/shopify\/CartLine\/a75fa865-13cd-4101-ac71-adde91f15190",
        "quantity": 1,
        "variant": {
          "id": "gid:\/\/shopify\/ProductVariant\/39784597094513"
        },
        "cost": {
          "amountPerQuantity": {
            "amount": "45.0",
            "currencyCode": "USD"
          }
        },
        "byobBundleId": null,
        "byobParentId": null,
        "byobGroupIndex": null,
        "byobUniqId": null
      },
      {
        "id": "gid:\/\/shopify\/CartLine\/4b7d5b0e-2f56-4746-a980-777b859b62ca",
        "quantity": 1,
        "variant": {
          "id": "gid:\/\/shopify\/ProductVariant\/40237443088497"
        },
        "cost": {
          "amountPerQuantity": {
            "amount": "28.0",
            "currencyCode": "USD"
          }
        },
        "byobBundleId": null,
        "byobParentId": null,
        "byobGroupIndex": null,
        "byobUniqId": null
      },
      {
        "id": "gid:\/\/shopify\/CartLine\/eefc0cfd-fe3b-4cf6-be80-0803e9eda44f",
        "quantity": 1,
        "variant": {
          "id": "gid:\/\/shopify\/ProductVariant\/15424009306225"
        },
        "cost": {
          "amountPerQuantity": {
            "amount": "86.0",
            "currencyCode": "USD"
          }
        },
        "byobBundleId": null,
        "byobParentId": null,
        "byobGroupIndex": null,
        "byobUniqId": null
      }
    ]
  },
  "cartTransform": {
    "bundlesList": {
      "type": "json",
      "value": "{}",
      "jsonValue": {}
    }
  }
}

byobBundleId: attribute(key: “_ByobBundleId”) {
key
value
}
byobParentId: attribute(key: “_ByobParentId”) {
key
value
}
byobGroupIndex: attribute(key: “_ByobGroupIndex”) {
key
value
}
byobUniqId: attribute(key: “_ByobUniqId”) {
key
value
}

Line items properties from cart object:

“properties”: {
“_ByobBundleId”: “199”,
“_ByobParentId”: “gid://shopify/ProductVariant/43051480383601”,
“_ByobGroupIndex”: “0”,
“_ByobUniqId”: “mmgdtqjpiwyr7ynnphl”
},

2

Hey @Northwrd_Dev - thanks for sharing all of the info here. I can’t say for sure without knowing what the exact shop’s configuration is, but one common reason for issues like this is if the shop has other cart transform functions enabled on it that conflict with each other.

I’d double check with the merchant to see if this is the case, and if so/even if not, if you’re open to sharing the myshopify.com URL for the shop and the app ID for the app your cart function is attached to, we can definitely look into this further.