Unable to get the list value returned by the json query from the ansible facts

I am trying to get the size_available value for the /home filesystem from the ansible facts.

I am using the following code after setting gather_facts: True

{{ansible_facts['mounts']|json_query('[?mount==`/home`].size_available')}}

This way I get something like this [34545646] with msg: from the debug module.
I need to compare this value to a static one and continue or not the playbook but when I try:

{{ansible_facts['mounts']|json_query('[?mount==`/home`].size_available')[0]}}

I get:

"msg": "template error while templating string: expected token 'end of print statement', got '['. String: > {{ansible_facts['mounts']|json_query('[?mount==`/home`].size_available')[0]}}

Even if the type_debug shows me the result should be indeed a list that should be accessible by the [0] extension.

>Solution :

You need to parenthesize the initial expression before attempting to index the result, like this:

{{
  (
    ansible_facts['mounts'] |
    json_query('[?mount==`/home`].size_available')
  )[0]
}}

E.g., if I run this playbook on my system:

- hosts: localhost
  gather_facts: true
  tasks:
    - debug:
        msg: >-
          {{
            (
              ansible_facts['mounts'] |
              json_query('[?mount==`/home`].size_available')
            )[0]
          }}

I get this output for the debug task:

TASK [debug] ********************************************************************************************
ok: [localhost] => {
    "msg": "402658955264"
}