Ansible – Reject Items from List of Dicts with Specific Attribute in Jinja2

ansiblejinja2

I have a list of dicts like this:

list_of_dicts:
  - name: Item1
  - name: Item2
    type: special
  - name: Item3
  - name: Item4
    type: small

As you can see, not all items have a type attribute. Context: If no type attribute is set, that means the item is of the default type.

I would like to select all items which are NOT of type special.

I've tried this: list_of_dicts | rejectattr('type', 'equalto', 'special')

Unfortunately, this fails with a AnsibleUndefinedVariable: 'dict object' has no attribute 'type' error because some of the items do not have a type.

What is a good way to solve this?

Best Answer

Edit: I actually didn't pay enough attention to the latest edit of the existing answer from @ranjandas and the following comments. My first solution is almost similar. I guess you are more interested by the second one.

Here are 2 different ways to achieve your requirement.

The first solution uses only filters available in ansible by default: rejectattr you already mentionned and its counterpart selectattr. The idea is to add two lists. The first one is made by selecting all dicts not having the type atttribute. The second one is made by selecting dict having the type attribute and rejecting those where it equals special.
For the second solution, I used the json_query filter which requires pip install jmespath on the controller. As you can see below it is much more compact.

The choice is yours !

The demo playbook:

---
- name: Show not so special items
  hosts: localhost
  gather_facts: false

  vars:
    list_of_dicts:
      - name: Item1
      - name: Item2
        type: special
      - name: Item3
      - name: Item4
        type: small

  tasks:
    - name: Use select/rejectattr
      debug:
        msg: >-
          {{
            (list_of_dicts | selectattr('type', 'undefined') | list)
            +
            (list_of_dicts | selectattr('type', 'defined') | rejectattr('type', 'eq', 'special') | list)
          }}

    - name: Use json_query
      vars:
        query: "[?type != 'special']"
      debug:
        msg: "{{ list_of_dicts | json_query(query) | list }}"

Which gives:

PLAY [Show not so special items] **********************************************************************************************************************************************************************************

TASK [Use select/rejectattr] **************************************************************************************************************************************************************************************
ok: [localhost] => {
    "msg": [
        {
            "name": "Item1"
        },
        {
            "name": "Item3"
        },
        {
            "name": "Item4",
            "type": "small"
        }
    ]
}

TASK [Use json_query] *********************************************************************************************************************************************************************************************
ok: [localhost] => {
    "msg": [
        {
            "name": "Item1"
        },
        {
            "name": "Item3"
        },
        {
            "name": "Item4",
            "type": "small"
        }
    ]
}

PLAY RECAP ********************************************************************************************************************************************************************************************************
localhost                  : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Related Solutions

Ansible | Access multi dimensional variable for when conditional in nested loop task

Is this the expression that you're looking for?

tasks:                                                                                     
  - debug:
      msg: "{{ result_CornerConfiguration.results[0]['stdout'] }}"

Loop with json_query to iterate:

  tasks:                                                                                     
    - debug:                                                                                 
        msg: "{{ item }}"                                                                    
      loop: "{{ result_CornerConfiguration | json_query('results[*][stdout]') }}"

Using Ansible ini_file with nested dict

I don't know of a way to do this with ansible by default other than using your "flatted" version. Fortunately you can have the best of both worlds and write your own filter plugin for flattening the dict for you. Just add somthing like the following to the filter_plugins directory in your project directory or in ~/.ansible/plugins/filter_plugins and name it something like filters.py:

class FilterModule(object):
    def filters(self):
        return { 'ini_dict_flatten': self.ini_dict_flatten }

    def ini_dict_flatten(self, arg):
        ret = []
        for section, subdict in arg.items():
            for key, value in subdict.items():
                ret.append(dict(section=section,
                                key=key,
                                value=value))
        return ret

After this you can use the new filter in your project like this:

- hosts: localhost
  tasks:
    - ini_file:
        path: /tmp/test.ini
        create: yes
        section: "{{ item.section }}"
        option: "{{ item.key }}"
        value: "{{ item.value }}"
      loop: "{{ inidict | ini_dict_flatten }}"
  vars:
    inidict:
      section1:
        option1: value1
        option2: value2
      section2:
        option1: value1
        option2: value2

It helps sometimes if you know python since that way you can write your own plugins for ansible.

EDIT: I will include a much less readable and not recommended solution as well. Since the loop: works with json formatted strings and jinja2 is applied to strings in ansible before they're processed you can use jinja logic to create the "flattend" for you directly in the playbook. This solution is a lot uglier and less reusable than writing your own filter but thecnically still works.

- hosts: localhost
  vars:
    inidict:
      section1:
        option1: value1
        option2: value2
      section2:
        option1: value1
        option2: value2
  tasks:
    - ini_file:
        path: /tmp/test.ini
        create: yes
        section: "{{ item.section }}"
        option: "{{ item.key }}"
        value: "{{ item.value }}"
      loop: >-
        [
        {% for section, subdict in inidict.items() %}
          {% for key, value in subdict.items() %}
            {'section': '{{ section }}',
             'key': '{{ key }}',
             'value': '{{ value }}'}
            {% if not loop.last %}
              ,
            {% endif %}
          {% endfor %}
          {% if not loop.last %}
            ,
          {% endif %}
        {% endfor %}
        ]

Best Answer

Related Solutions

Ansible | Access multi dimensional variable for when conditional in nested loop task

Using Ansible ini_file with nested dict

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