How do I get Ansible's json_query to return a value from this JSON document

After several hours of beating my head against this (not to mention leaving it for a day) I'm pretty much stumped on trying to figure out why I can't JMESPath to return a value in Ansible.

I have a task which runs a shell command and returns the following output:

[
    {
        "ansible_loop_var": "item",
        "changed": false,
        "cmd": [
            "pvesh",
            "create",
            "/access/users/user@pve/token/pve-apikey",
            "-privsep=0",
            "--output=json"
        ],
        "delta": "0:00:00.707130",
        "end": "2022-09-22 12:28:43.746253",
        "failed": false,
        "invocation": {
            "module_args": {
                "_raw_params": "pvesh create /access/users/\"user@pve\"/token/\"pve-apikey\" -privsep=0 --output=json",
                "_uses_shell": false,
                "argv": null,
                "chdir": null,
                "creates": null,
                "executable": null,
                "removes": null,
                "stdin": null,
                "stdin_add_newline": true,
                "strip_empty_ends": true,
                "warn": false
            }
        },
        "item": {
            "token": "pve-apikey",
            "user": "user@pve"
        },
        "msg": "",
        "rc": 0,
        "start": "2022-09-22 12:28:43.039123",
        "stderr": "",
        "stderr_lines": [],
        "stdout": "{\"full-tokenid\":\"user@pve!pve-apikey\",\"info\":{\"privsep\":\"0\"},\"value\":\"dc2aa48f-daf6-4efe-b95e-83774a588988\"}",
        "stdout_lines": [
            "{\"full-tokenid\":\"user@pve!pve-apikey\",\"info\":{\"privsep\":\"0\"},\"value\":\"dc2aa48f-daf6-4efe-b95e-83774a588988\"}"
        ]
    }
]

I'm now trying to obtain the UUID returned as value in the stdout_line using json_query and this is far as I can get:

    - debug:
        msg: "{{ token | community.general.json_query(query) }}"
      vars:
        query: '[].stdout'

This json_query returns the following output:

"msg": [
        "{\"full-tokenid\":\"tfuser@pve!tfe-pve-apikey\",\"info\":{\"privsep\":\"0\"},\"value\":\"e47e82d4-6798-47ea-9592-c7cf55cc8b61\"}"
    ]

I believe that this is a list, so I've tried extending the json_query as [].stdout[].value but that returns null. I've tried various permutations but so far nothing seems to work.

Any advice on how to proceed would be very welcome!

Solution

The items of the list stdout_lines are strings. You can test it. For example,

    - debug:
        var: output.0.stdout_lines.0|type_debug

gives

  output.0.stdout_lines.0|type_debug: AnsibleUnsafeText

Convert the items to dictionaries. For example

    - debug:
        var: output.0.stdout_lines.0|from_yaml

gives

  output.0.stdout_lines.0|from_yaml:
    full-tokenid: user@pve!pve-apikey
    info:
      privsep: '0'
    value: dc2aa48f-daf6-4efe-b95e-83774a588988

To get the UUID, declare the variable

    UUID: "{{ output|map(attribute='stdout_lines')|
                     map('map', 'from_yaml')|list|
                     json_query('[].value') }}"

This gives the list of the values

  UUID:
  - dc2aa48f-daf6-4efe-b95e-83774a588988

^{Example of a complete playbook for testing
- hosts: localhost

vars:

output: "{{ lookup('file', 'output.json') }}"
UUID: "{{ output|map(attribute='stdout_lines')|
map('map', 'from_yaml')|list|
json_query('[].value') }}"

tasks:

- debug:
var: output.0.stdout_lines.0|type_debug
- debug:
var: output.0.stdout_lines.0|from_yaml
- debug:
var: UUID}