Expand function, lists in template entity attribute and self-referencing

Configuration
1

For an enhancement request I created the template sensor below as an example (Binary_sensor group, add attributes to show which entities in the group are on resp. off)

It’s intention is to mimic a binary_sensor group but add attributes that show which group members are on and which are off.
The implementation below seems to work but I’m not 100% sure I fully understand what I am doing here ;-).

  1. I’m fairly new to the expand() function and still struggle a bit what exactly it is doing. Also it seems that this function is not part of the Jinya specification but an add-on by Home Assistant - right ? Does anyone have a good reference to learn more about it ?
    The initiailization for self reference via this also seems to be tricky, what comes first ? The only way I was able to make sure I don’t get errors in the logbook at startup was to add defaults to all those references.

  2. I read somewhere in the docs that attributes can be of any type, including lists. The only way I was able to create such a list for an attribute was with the somewhat clumsy notation below (I’m glad though @petro mentioned this way in a post - otherwise it wouldn’t have worked at all). Is there a better way to specify a static list for an attribute? Idealy I would be able to use the node anchors I had created and used in the groups - that way the lists could be re-used.

template:
  binary_sensor:
  - name: "Contact Sensors"
    # important to set a default, this.attributes.sensors_on may not yet be initialized when the state is evaluated
    state: "{{ (this.attributes.sensors_on | default([])) != [] }}" 
    attributes:
      entity_id: >
        {% set sensors = [ 
          "binary_sensor.contact_a_state",
          "binary_sensor.contact_b_state",
          "binary_sensor.contact_c_state"
        ] %}
        {{ sensors }}
      sensors_on: "{{ expand(this.attributes.entity_id | default([])) | selectattr('state', 'eq', 'on') | map(attribute='entity_id') | list }}"
      sensors_off: "{{ expand(this.attributes.entity_id | default([])) | selectattr('state', 'eq', 'off') | map(attribute='entity_id') | list }}"
    device_class: "opening"
1 Like
2

Dear Michael,

Many thanks for sharing this code, I have used this in my approach to get an alarm on tripping a certain number of sensor in a certain timeframe (I will update the link here later).

One small comment, the indentation for the sensors_on and off is a little off, I had to reduce it to make these attributes come to life.

Again, many thanks for this mainly elegant solution.

kind regards,

Ben

3

Glad you could make use of this snippet. you are right, the two lists are wrongly indented on the post, they are proper im my installation though.

4

I simplified the templates a bit :slight_smile:

template:
  binary_sensor:
  - name: "Contact Sensors"
    # the get function is used to provide a default in case the attribute is not initialized
    state: "{{ this.attributes.get('sensors_on', []) != [] }}" 
    attributes:
      entity_id: >
        {{
          [ 
            "binary_sensor.contact_a_state",
            "binary_sensor.contact_b_state",
            "binary_sensor.contact_c_state"
          ]
        }}
      sensors_on: "{{ this.attributes.get('entity_id', []) | select('is_state', 'on') | list }}"
      sensors_off: "{{ this.attributes.get('entity_id', []) | select('is_state', 'off') | list }}"
    device_class: "opening"
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5

FWIW, given recent enhancements, I would suggest labeling the desired entities with the word contact and then referencing them with label_entities.

- binary_sensor:
    - name: "Contact Sensors"
      state: "{{ this.attributes.get('sensors_on', []) != [] }}" 
      device_class: opening
      attributes:
        sensors_on: "{{ label_entities('contact') | select('is_state', 'on') | list }}"
        sensors_off: "{{ label_entities('contact') | select('is_state', 'off') | list }}"

Reference

Labels

If for some reason you still want to see a list of all contact sensors in an entity_id attribute:

- binary_sensor:
    - name: "Contact Sensors"
      state: "{{ this.attributes.get('sensors_on', []) != [] }}" 
      device_class: opening
      attributes:
        entity_id: "{{ label_entities('contact') }}"
        sensors_on: "{{ this.attributes.get('entity_id', []) | select('is_state', 'on') | list }}"
        sensors_off: "{{ this.attributes.get('entity_id', []) | select('is_state', 'off') | list }}"
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