Sitecore Headless Forms - Hidden Field Using Query Value

This one goes out to @AJS on Sitecore slack who asked how they could implement the query string provider in Sitecore Forms (headless/JSS).

Firstly, make sure you add the QueryStringProvider from Sitecore Forms Extensions, as well adding the required Sitecore item(s) to your instance.

Once that's done see the Sitecore documentation on adding a React/Next.JS form to your headless app.

Finally you're ready to implement a custom field factory (see my previous post) with a custom hidden element, setting the value based on the value from the query string:

Enjoy!