Register variables with dynamic names from with_items - ansible

Question

I would like to register variables from lookup results.
My inventory:
rrules:
- name: r1
start_date: '2022-01-01 13:00:00'
- name: r2
start_date: '2022-02-02 12:00:00'
Task looks like:
- name: Create a string for a schedule
debug:
msg: "{{ query('awx.awx.schedule_rrule', 'minute', start_date=item.start_date) }}"
register: "{{ item.name }}"
with_items:
- "{{ rrules }}"
When I run the playbook, I get the error:
fatal: [127.0.0.1]: FAILED! => {"msg": "Invalid variable name in 'register' specified: '{{ item.name }}'"}

Answer 1

Using the register of a debug task is a terrible idea.
Do not do that, instead, use the proper module to register variables, which is the set_fact module.
With it, you can register variable with a dynamic name, as you intended it:
- set_fact:
"{{ item.name }}": >-
{{ query(
'awx.awx.schedule_rrule',
'minute',
start_date=item.start_date
) }}
loop: "{{ rrules }}"
Given those tasks:
- set_fact:
"{{ item.name }}": >-
{{ query(
'awx.awx.schedule_rrule',
'minute',
start_date=item.start_date
) }}
loop: "{{ rrules }}"
vars:
rrules:
- name: r1
start_date: '2022-01-01 13:00:00'
- name: r2
start_date: '2022-02-02 12:00:00'
- debug:
var: r1
- debug:
var: r2
It will yield:
TASK [set_fact] ***************************************************************
ok: [localhost] => (item={'name': 'r1', 'start_date': '2022-01-01 13:00:00'})
ok: [localhost] => (item={'name': 'r2', 'start_date': '2022-02-02 12:00:00'})
TASK [debug] ******************************************************************
ok: [localhost] =>
r1: DTSTART;TZID=Europe/Paris:20220101T130000 RRULE:FREQ=MINUTELY;INTERVAL=1
TASK [debug] ******************************************************************
ok: [localhost] =>
r2: DTSTART;TZID=Europe/Paris:20220202T120000 RRULE:FREQ=MINUTELY;INTERVAL=1