RFC: Templates that generate non-strings about architecture

[balloob]

Note that I wouldn't want people to return objects. It's mainly for lists.

[maddox]

Note that I wouldn't want people to return objects. It's mainly for lists.

Good luck communicating that and setting the right expectations :/

Are there any other cases this can solve other than lists? If not, why not name the wrapper something super specific like list() and interpret it like that? That could set better expectations.

Is simple string matching out of the question? Just checking to see if an array format is returned, and then parsing it into a list?

[OttoWinter]

Are there any other cases this can solve other than lists?

I would say having templated attributes (useful for things like lights, universal media_player, ...) could also be done this way - if it's a thing Home Assistant wants to add support for.

[balloob]

Both lists and objects can already be created. See this example: home-assistant/core#12469

Maybe adding this is not needed.

[OttoWinter]

Oh, that's right - good catch! We should say that it only works when the cv.template_complex is used:

https://github.com/home-assistant/home-assistant/blob/e4ef6b91d6552bb6f1d49b579f94a161944ce1a4/homeassistant/helpers/config_validation.py#L349-L360

Next, I want to point out that this doesn't always look super clean. I mean it's not a problem, but worth pointing out: Suppose we have a variable rgb_color = '255,0,255' in a script. In order to pass it into light.turn_on, we'd have to write:

service: light.turn_on
data_template:
  entity_id: ...
  rgb_color:
    - "{{ rgb_color.split(',')[0]|int }}"
    - "{{ rgb_color.split(',')[1]|int }}"
    - "{{ rgb_color.split(',')[2]|int }}"

whereas {{ json(rgb_color.split(',') | map('int') | list) }} would be a bit nicer. Again, purely cosmetical and not really a problem.

[balloob]

It would be json({{rgb_color.split(',') | map('int') | list}}) as json is not an official function but something bolted on top of the template renderer. Still looks horrible.

I've posted an example with a script with data_template to the forums and let's leave it at that for now.

[maddox]

Is it in the docs somewhere?

[balloob]

Don't think so. PR welcome 😉