Ansible – How to Get a Subelement of a Nested List of Dictionaries

I'd like to build our DNS zones via Ansible. The user should just maintain one variable for the forward-lookup zones (e.g. foo.bar). Reverse-lookup zones (0.0.10.in-appr.arpa) should be auto-generated with Ansible.

The forward-lookup zone variable should look like

dns_zone_config:
    - name: "internal.foo.bar"
      acl:
        - 10.180.0.0/24
        - 10.180.8.0/24
      hosts:
        - name: "fileshare"
          ip: 10.180.0.200
    - name: "infra.foo.bar"
      acl:
        - acl-intern
      hosts:
        - name: "testhost1"
          ip: 11.180.0.100
          no_ptr_record: true
        - name: "testhost2"
          ipv6: fe80::1
        - name: "testhost3"
          ip: 11.180.0.200
    - name: "mx.foo.bar"
      mx:
        - name: "xxxx"
          priority: xxxx
          target: xxxx

dns_zone_config is a list of dictionaries that may contains a key called "hosts" which is again a list of dictionaries.

My current way looks like:

- name: Collect all networks
  include_tasks: 01-networks.yml
  loop: "{{ dns_zone_config }}"
  when: item_dns_zone_config.hosts is defined
  loop_control:
    loop_var: item_dns_zone_config

#from 01-networks.yml
- name: Determine IPv4 networks
  set_fact:
    ipv4_networks: "{{ (ipv4_networks | default([])) + [ item.ip ] }}"
  loop: "{{ item_dns_zone_config.hosts }}"
  when: item.ip is defined and (item.no_ptr_record is not defined or not item.no_ptr_record)

I double loop over dns_zone_config and their host entries. This is very inefficient and slow. I'm pretty sure this can be solve smarter 😀

Basically I just need list of all IPs of all zones. I tried json_query() and selectattr() filters but I'm struggling on the fact that not every host entry has IPv4 or IPv6 addresses defined. And I don't want contains IPs if a no_ptr_record: true variable is defined (false or not defined is ok).

From the snippet above the list would only contain:
ipv4_networks:

['10.180.0.200','11.180.0.200']