Paste a parcel locker ID from a map in the cart as a variable into the checkout shipping method list

Technical Q&A
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Topic summary

  • Goal: Add a map widget on the cart page to let customers choose a parcel locker/point, then pass that selection into checkout so the chosen locker appears as the preselected shipping option (first row).

  • Current setup: A custom app connects to a courier API, finds the 3 nearest parcel lockers, and displays them in the Checkout Shipping selection page. A screenshot was provided to illustrate this.

  • Constraint: On the Shopify plan, checkout.liquid is not accessible, so the widget must run on the cart page and its selection needs to be transferred to checkout.

  • Request: Determine if the cart widget’s selected locker can be stored/passed as a variable to checkout and used to preselect the matching shipping method. Rationale: Since the custom app can already fetch and render lockers in checkout, the user expects this should be possible.

  • Resources: Widget documentation link provided (widget-maps.paxy.pl). Widget code available upon request.

  • Status: No solution or confirmation yet; question remains open.

Summarized with AI on January 31. AI used: gpt-5.
1

Dear Shopify,

I have a Custom App that connect to one of my courier firms and selects the 3 closest parcel lockers and presents them inside the Checkout Shipping selection page. I have attached a screenshot for this.

Now, I would like to add a widget-map into my cart page (as I dont have access to my checkout.liquid file, as I am on a “Shopify” plan). This widget will fetch the parcel locker or parcel point that the customer selects from, and I would like to pass this selection to the checkout and the checkout shipping selection page.

Would this be possible to show the selected parcel locker from the widget map as a variable that is later shown inside the checkout shipping option as a preselection on the first row?

Since our custom app can fetch parcel lockers from an api and show them inside the checkout shipping list, why would this not be possible?

The widget documention:

https://widget-maps.paxy.pl/docs/intro

I have the widget code if needed!

Sincerely,
HUGE Thanks to you all!