Domain field

This module defines a Domain Reference field type that will allow you to reference any domain by it's machine name.

By default, Domain Access doesn't define any field type that lets you reference domains.
A patch has been submitted to the issue queue (See #1684920: Add a 'domain' field type) about two years ago to implement that feature but it hasn't been committed and will probably never be.

For those who don't want to maintain a patch during the Domain Access lifecycle, I created this module.
The Domain entity module also provide it's own field, but unfortunately, it stores the domain_id instead of the machine name which is problematic when you have multiple environments.