ansible_obj_creation.yml

# Create list using a specific attribute value
## Original task
- name: "Set fact"
  set_fact:
    hdd_list: "{{ hdd_list|default([]) + [item.key] }}"
  with_dict: "{{ ansible_facts.ansible_devices }}"
  when: item.value.model == "Virtual disk"

## Output
 "hdd_list": [
        "sda",
        "sdb"
    ]

# Create list with multiple items and their attrs
##  Task
- name: "Set fact hdd_perfs"
  set_fact:
    hdd_perfs: "{{ hdd_perfs|default([]) + [ {'name': item.item, 'device': item.stdout_lines[1], 'cache_read': item.stdout_lines[2], 'buffer_read': item.stdout_lines[3]} ] }}"
    #hdd_perfs: "{{ hdd_perfs|default([]) + [item.name] }}"
  with_items: "{{ disks_perfs.results }}"

## Output
"hdd_perfs": [
        {
            "buffer_read": " Timing buffered disk reads: 790 MB in  3.00 seconds = 263.27 MB/sec",
            "cache_read": " Timing cached reads:   10708 MB in  2.00 seconds = 5358.69 MB/sec",
            "device": "/dev/sda:",
            "name": "sda"
        },
        {
            "buffer_read": " Timing buffered disk reads: 522 MB in  3.00 seconds = 173.87 MB/sec",
            "cache_read": " Timing cached reads:   7654 MB in  2.00 seconds = 3829.39 MB/sec",
            "device": "/dev/sdb:",
            "name": "sdb"
        }
    ]

# Create dict with attrs
# Task
- name: add new key / value pairs to dict
  set_fact:
    my_dict_var: "{{ my_dict_var|default({}) | combine({item.key: item.value}) }}"
  with_items:
  - { key: 'sda', value: {'device': "mondevice",'device2': "mondevice"} }
  - { key: 'sdb', value: {'device': "mondevice",'device2': "mondevice"} }

## Output
[host] => {
    "my_dict_var": {
        "sda": {
            "device": "mondevice",
            "device2": "mondevice"
        },
        "sdb": {
            "device": "mondevice",
            "device2": "mondevice"
        }
    }
}