Custom discount / graphql limits

[dan-hrpr]

I have created a discount app that uses a resource picker to only apply the discount to selected products.

The problem is that when I select more than 4 products I get an error generated from by the Shopify function.

Error parsing selectedProducts: TypeError: cannot read property 'reduce' of undefined

It works fine with any combination of variants and in the admin interface the product list saves with more than 4 products selected so the products are being stored in the metafield there's just a problem when the discount function retrieves them when there's more than 4.

I've tried to get the discount metfields from GRaphicQL but I couldn't work it out.

here's my input query for the discount function.

query Input {
  cart {
    lines {
      quantity
      merchandise {
        __typename
        ...on ProductVariant {
          id
        }
      }
    }
    buyerIdentity {
      email
      customer{
        metafield(namespace: "loyalty-discount", key: "loyalty_tier") {
          value
        }
      }
    }
  }
  discountNode {
    functionConfiguration: metafield(namespace: "$app:loyalty-discount", key: "function-configuration") {
      value
    }
    selectedProducts: metafield(namespace: "$app:loyalty-discount", key: "selected-products") {
      value
    }
  }
}

Thanks Dan

[tobebuilds]

Hi Dan-Hrpr,

This doesn't seem like you're running into a limit (e.g. instruction count limit or input query limit).

Specifically, the error message "TypeError: cannot read property 'reduce' of undefined" makes me think it's a JS runtime error.

If you console.error the input when your function runs, you might be able to identify the cause. Maybe `selectedProducts`, or one of its properties, is undefined.

Best,

Tobe

[dan-hrpr]

Hi Tobe,

It is undefined but only when I save more than 4 products in it.

Cheers Dan

[tobebuilds]

You might be running into the 10kb metafield size limit, then. I recommend only storing the IDs of products. I don't know if you are storing other information about products in the metafield, but it fills up fast.

[dan-hrpr]

I did think that but it works in the backend in the product selector.

So if I add 20 products in the product selector and then save the discount then when I edit the discount again the 20 products are still selected.

I will try and save the variant id's only like you suggest.