Updating a product price when custom checkbox is selected

Retired Boards Appdev Store Design
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Topic summary

Goal: Implement a custom product option in a PDP app block that, when a checkbox is selected, shows a dropdown (values from product metafields) and affects pricing/cart.

Proposed approaches:

  • Dynamically update the displayed product price when an option is selected.
  • Add the selected option as a separate line item at add-to-cart time.

Constraints and context:

  • Avoid creating product variants to prevent extra inventory/variant management.
  • Cart Transform Functions/API are not viable because they’re limited to Shopify Plus; solution must work for non-Plus stores.
  • Dropdown values come from product metafields (custom data fields) created via the app.
  • Screenshots provided illustrate the UI state with and without an option selected.

Status: Request for suggestions/resources on implementation details. No solutions or decisions yet; key question remains how to adjust price or cart without variants and without Plus-only APIs.

Summarized with AI on December 28. AI used: gpt-5.
1

Hello,

I am working on an app that users would be able to install in their stores. This app would provide a store block for a product details page. The block will show a checkbox in which a user can select. It would then display a drop-down of options a user must choose from. These dropdown values are populated from the product’s metafields which are also created via the app.

I would like to use one of the following solutions (whichever is simpler) but how to implement it is where I am having trouble:

  1. Update the price of the product for the user when an option is selected
  2. Add the selected option as an additional line item when they add the product to their cart.

Some additional context:

  • Creating product variants with these options should be avoided if possible in order to avoid additional inventory and variant management for the stores using the app.
  • The Cart Transform Update API was a possible solution I looked into but it is only available for stores on the Shopify Plus plan, so this will not work as some stores may not be on Shopify Plus.

Any suggestions or resources would be appreciated!

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