Follow-up to #2809971: composable forms and Getting NYU onto YAML Form


Site builders like be able to 'extend' a base form or combine multiple forms into a composite form.

Proposed resolution

Provide mechanism to build composite and/or base forms

Remaining tasks

User interface changes

API changes

Data model changes



jrockowitz created an issue. See original summary.

jrockowitz’s picture

Right now, writing a custom composite element is best way to get a group of reusable elements.

Below are the two plugins and templates used to implement an Address element.

fenstrat’s picture

Project: YAML Form » Webform
Version: 8.x-1.x-dev » 8.x-5.x-dev
anpolimus’s picture

Issue tags: +KyivCampCS17
Sarah10’s picture


Sarah10’s picture

Hi, I have created two plugins and template to implement custom composite element.

  • Then I have created fields, but they are not showing up anywhere.
  • I have enabled the option for "Unlimited values - it still didn't show up.
  • And then I tried unlimited values in the table format. It worked.

What am I doing wrong? Why is it not showing up without table format?


jrockowitz’s picture

You must configure and check 'Display elements in table columns'.

Sarah10’s picture

Yes, If I check the box "Display elements in table columns" - It is working perfectly fine.

If I do not check the box - Nothing is coming up., It's totally empty like blank screen

Sarah10’s picture

And even if I make it as "Limited" and number of values as "1" - It is showing up a blank screen.

jrockowitz’s picture

@sattapuram You might need to slowly duplicate an existing composite element and figure out what is missing from your custom element.

Sarah10’s picture

I figured it out....It is because of the theme..
Reverting to the core theme solved the issue.


Sarah10’s picture

@jrockowitz How do I include File upload field in my composite element?

I tried in different ways...the field is showing up but the file is nowhere saved/uploaded.

jrockowitz’s picture

Complex elements (aka entity and file references) are not supported by composites without some hacking.

I am working on #2884624: Allow composite sub elements to be formatted which should help support complex elements with in composites.