ansible: 'default' filter that treats the empty string as not defined

Question

If I do this:

- set_fact:
    NEW_VARIABLE: "{{ VARIABLE | default('default') }}"

and VARIABLE is the empty string (""), than the default not triggering.

I could do this:

- set_fact:
    NEW_VARIABLE: "{{ VARIABLE | default('default') }}"
- set_fact:
    NEW_VARIABLE: "default"
   when: VARIABLE == ""

But I actually want to do this in a loop. So it would be much easier if I could do this using ansible filters and not conditionals.

Is this possible? Are there ansible filters that work like default but treats "" as not defined?

Answer 1

You have to set second argument of default to true

{{ VARIABLE | default('default', true) }}

https://docs.ansible.com/ansible/latest/user_guide/playbooks_filters.html#defaulting-undefined-variables