How to create a custom form in composer?

[isaac (Isaac Janzen)]

You can take a look at

Introducing Experimental Form Templates

Hello, Discourse Meta Community! We are excited to introduce a new experimental feature, form templates. With it, you can enforce a structured form with data validation as part of the topic creation flow. [multiple_form_templates] Enabling the feature The feature is hidden behind a site-wide experimental flag. To enable it, just turn on the experimental_form_templates site setting under Admin ▸ Settings. Managing the templates The form templates can be created, edited, and deleted a…

I believe it should fit your use case at a low level

If you are going to be fetching data from a custom API, you may need a custom plugin / theme.