Ansible loop with array - arrays

Question

Could someone let me know how we can create a code as below?
- name: TEST1
set_fact:
list_a: "{{ list_a + [item.json.SearchResult.resources] }}"
with_items:
- "{{ source_list.results[0] }}"
- "{{ source_list.results[1] }}"
- "{{ source_list.results[x] }}"
... (unknown how many items in result from API)
vars:
list_a: []
source_list.results[x] comes from an API result. The reason why I need to create an array is that the number of API result is maximum 100. But there are over 500 items.

Answer 1

Note: since we have no idea what you initial data structure looks like exactly, the below might not be 100% fitting your use case. For your next questions, please read How to ask and pay attention to the Minimal, complete and reproducible example section. Thanks
You are taking this the wrong way. Simply extract the attribute you need from each result using the map(attribute=x) Jinja2 filter.
For the below I inferred (see above note) that:
you called your API with ansible.builtin.uri in a loop to get batches of 100 results which are returned as a list in the SearchResult.ressources field
you want in the end a flattened list where all resources are at top level
- name: Show my list of single attributes
ansible.builtin.debug:
var: "source_list.results
| map(attribute='json.SearchResult.resources') | flatten"
You actually don't need to set_fact:
For a single use, just use the above expression directly in the relevant parameter (e.g. loop or a module param....) or eventually declare this in a var at task level.
If you want to reuse this in different parts of your playbook, just declare a var at play level and expand it anywhere once you have called your API and populated the source_list var. In that case, just add a default value to prevent an error if API was not yet called.
Example for the second case above in this pseudo playbook
---
- hosts: localhost
gather_facts: false
vars:
list_a: "{{ source_list.results | d([])
| map(attribute='json.SearchResult.resources') | flatten }}"
tasks:
- name: "This will return an empty list (i.e. [])
as we did not populate source_list yet"
ansible.builtin.debug:
var: list_a
- name: Call our API and register source_list
ansible.builtin.uri:
uri: https://my.api.com/api/v1/some/endpoint
# [... more parameters here ... ]
loop: "{{ my_list_of_ressources }}"
register: source_list
- name: "This will now return a populated list
after calling the API and registering source_list"
ansible.builtin.debug:
var: list_a
Now, to still give a direct answer to your initial question: you can construct that list iteratively inside a set_fact task. This is definitely not efficient as it involves a task running inside a loop (both unneeded as demonstrated above) and possibly on multiple hosts in your play. But for learning purpose, here it is:
- name: very inefficient way to get the same result as above
set_fact:
list_a: "{{ list_a | d([]) + item.SearchResult.resources }}"
loop: "{{ source_list.results }}"

Answer 2

After reading #Zeitounator's answer, I realized I was taking this the wrong way. I used the idea in the answer (json query and flatten) and I changed my task to the below which works as expected.
- name: Create ID list from API result data
set_fact:
list_a: "{{ source_list | json_query('results[*].json.SearchResult.resources[*].id') | flatten }}"
- name: API get again with id
uri:
url: "{{ request_url }}/{{ item }}"
...
register: result_data
with_items:
- "{{ list_a }}"