Supported setting types of Shopify.extension.toml

Topic summary

A developer is attempting to clone a custom Shopify checkout app (CheckoutPlus) but cannot find documentation for implementing a select/dropdown field in the Shopify.extension.toml configuration file.

Current situation:

  • The official Shopify documentation for checkout UI extension settings doesn’t list a select field type
  • The developer has shared screenshots showing the desired dropdown functionality from the existing app
  • They’ve provided their current Shopify.extension.toml code, which uses single_line_text_field with a “choices” validation containing options like “Default”, “Heading-small”, “Heading-medium”, “Text-small”, etc.

Key question:
How to properly implement a select/dropdown field in the extension configuration, as this field type appears missing from the supported settings types documentation.

The discussion remains open with no solution provided yet.

Summarized with AI on November 4. AI used: claude-sonnet-4-5-20250929.

Hi,
I want to ask about setting types, I see there is no select field

I want to field like attached screenshot

This is custom app, you can see https://apps.shopify.com/checkoutplus?show_store_picker=1 this app, I am trying to clone the extension , but I cannot write code for select field

This is Shopify.extension.toml file

[[extensions.settings.fields]]
key = "label_text_size"
type = "single_line_text_field"
name = "Label Text Size"
description = "Enter a label for the upsell"

[[extensions.settings.fields.validations]]
name = "choices"
value = "[\"Default\", \"Heading-small\", \"Heading-medium\", \"Heading-large\", \"Text-small\", \"Text-medium\", \"Text-large\", \"Text-xlarge\"]"