Unique Filter of List in Jinja2

Question

I have the following YAML structure:

bri:
  cards:
    - slot: "1"
      subslot: "0"
      ports: 2
    - slot: "1"
      subslot: "1"
      ports: 2
    - slot: "1"
      subslot: "2"
      ports: 2
    - slot: "2"
      subslot: "0"
      ports: 2
    - slot: "2"
      subslot: "1"
      ports: 2

I am attempting to use Jinja2 to get a unique list of slots, i.e.:

['1', '2']

So far, I've managed to apply the following:

{{ bri.cards|map(attribute='slot')|list }}

Which gives me:

['1', '1', '1', '2', '2']

However, I don't seem to be able to find a way to get a unique list.

Ansible

Ansible appears to have a "unique" filter that can do this. But I'm not using Ansible in this case.

• http://docs.ansible.com/ansible/playbooks_filters.html#set-theory-filters
• ansible/jinja2 get unique subelements

My question

Can anyone suggest the best way to achieve this? Should (or can) this be done natively with Jinja2, or should I adopt an alternative approach?

Answer 1

You can do something like this (depends on how you parse the .yaml file - is it a list of dicts of dicts?):

{% set slots = [] %}
{% for slot in bri.cards if slot not in slots %}
    {% do slots.append(slot) %}
{% endfor %}

Answer 2

Edited - I did not see the bit about not being able to use the unique filter. For those that can use the unique filter you can do it this way

{{ bri.cards|map(attribute='slot')|unique|list }}

Answer 3

Similar to above by doru with the append functions, but I noticed Ansible doesn't load the 'do' module for Jinja2, working around that is possible as such: {{ bucket.append(client.client_id) }}

{% set slots = [] %}
{% for slot in bri.cards if slot not in slots %}
    {{ slots.append(slot) }}
{% endfor %}

So using {{}} syntax, you can still issue the append function call, and not have Ansible throw Jinja syntax errors.