Add val_tpl on HA discovery configuration - fix issue #939

[Odyno]

fix issue #939

[1technophile]

thanks for the proposal,
I would like to know how the switch goes back to OFF in this case?

[Odyno]

This is an interesting point, it all started here.

In short:
I created one Automation on HA that reset the switch... below the code

alias: Reset All Pirs
description: ''
trigger:
  - platform: state
    entity_id:
      - switch.2741642
      - switch.11031942
      - switch.....
    to: 'on'
    for: '00:00:05'
condition: [ ... ... ... ]
action:
  - delay:
      hours: 0
      minutes: 0
      seconds: 5
      milliseconds: 0
  - service: switch.turn_off
    target:
      entity_id: '{{ trigger.entity_id }}'

With more context:
Considerations that led me to this PR:

without the "val_tpl" no automatism will change the state of the switch, even if a "pl_on" is defined (and it is equal to the value) and even if on the MQTT topic we receive the update from "the real switch". So, in the end, we have a switch created by discovery that forces me into constraints (the "pl_on") and it is always stationary ( so... in my opinion just confusing and it is useless).

On the other hand, there is no info on pl_off, but is present the cmd_t that indicate how to change the state... so finally all are free to switch manually the sensor to something that is "on" (as specified on "pl_on") or not "on" ( so.... it can be just off).

If I were to look at the configuration without the "val_tpl" (according to the point of view) it is useless. If I try to interpret this "sensor", by giving the value "val_tpl", it clearly becomes the modelling of the sensor that provide triggers.

The sensor provide just the "event on" and is up to listener reset the trigger.

Open to discuss it!

[1technophile]

ok, I see, maybe it could be nice to add to the docs (integrate/home assistant) your script that you are using with this PR so as to set the status to OFF?

[Odyno]

ok!

[1technophile]

Thanks, could you rebase from development branch please

[Odyno]

done

[Odyno]

@1technophile let me stop this PR, I just discovered that this configuration create a lot of error on home assistant, because sometime the value is not present and on home assistant is raised a lot of warning and error

2021-05-13 18:37:56 ERROR (MainThread) [homeassistant.helpers.template] Template variable error: 'value_json' is undefined when rendering '{{ value_json.value | is_defined }}'
2021-05-13 18:37:56 ERROR (MainThread) [homeassistant.helpers.template] Error parsing value: 'value_json' is undefined (value: OFF, template: {{ value_json.value | is_defined }})