How to add line item properties to cart in Narrative theme?

Topic summary

Problem: custom personalization fields on product pages aren’t appearing in cart/checkout/order (Narrative theme).

Key guidance and fixes:

  • Use Shopify line item properties with inputs named as name=“properties[Your Property Name]” so values pass to cart/checkout.
  • Ensure inputs are inside the product form (…). In Narrative, the form is often included via a snippet (e.g., {% include ‘product-form’ %}); placing fields outside the form prevents submission.
  • A contributor tested moving the input into the form on the store and confirmed it then worked.
  • Correct resource shared: Shopify UI Elements Generator for line item properties (previous cart attribute code was incorrect for this use case).

Ongoing issues/updates:

  • Some users struggled to locate the actual form because it lives in a snippet rather than directly in product.liquid.
  • A later participant reported line item properties returning null despite placing fields within the form and shared product/cart code; no confirmed fix yet.
  • Another user on the Unsen theme noted HTML required validation isn’t enforced (fields can be empty) and asked how to link Add to Cart to validation; no resolution provided.

Notes: Code placement and snippet structure are central to understanding and resolving the issue.

Summarized with AI on January 4. AI used: gpt-5.

Where do I change it?