This was posted earlier here. I’ve added some improvements, mostly to avoid errors, and also added some additional stuff suggested by @erkr in this post
It can happen you want to store some data to use it in another automation, or make sure it’s still available after a restart of HA. You can use helpers for that (eg and input_text entity) but these are limited in which types you can store, and they can be easily edited in the GUI.
The configuration below creates a trigger based templates sensor which can be used to store data. As trigger based template sensors restore their state and attributes after a restart, the data will survive restarts.
You can also store any type of data in this sensor, it can be a string, decimal number, integer but also a list or dictionary.
Note: there is a limitation how much data you can store in an attribute. If it becomes too big, it will not be stored in the database, and can therefor not be retrieved. If you really want to store a lot of data, you can maybe create a separate sensor for that.
Sensor configuration
# this configuration can be placed in configuration.yaml
template:
- trigger:
- platform: event
event_type: set_variable
- platform: event
event_type: remove_variable
- platform: event
event_type: clear_variables
action:
- if: "{{ this.attributes.get('log_events', true) }}"
then:
- service: logbook.log
data:
name: "{{ trigger.event.event_type }}:"
message: >
{{ trigger.event.data.key | default('-') }}
{%- if trigger.event.event_type == 'set_variable' -%}
: {{ trigger.event.data.value | default('not defined!')}}.
{%- endif -%}
sensor:
- unique_id: 4a4c8e53-9e68-4198-9cc5-b336e228ea4d
name: Variables
state: Variables
attributes:
default_timestamp: true
log_events: false
variables: >
{% set current = this.attributes.get('variables', {}) %}
{% if trigger.event.event_type == 'set_variable'
and trigger.event.data.value is defined
and trigger.event.data.key is defined
%}
{% if trigger.event.data.get('set_timestamp', this.attributes.get('default_timestamp', false)) %}
{% set value = trigger.event.data.value %}
{% set value = value.isoformat() if value is datetime else value %}
{% set new = {trigger.event.data.key: {'value': value, 'timestamp': now().isoformat()}} %}
{% else %}
{% set new = {trigger.event.data.key: trigger.event.data.value} %}
{% endif %}
{{ dict(current, **new) }}
{% elif trigger.event.event_type == 'remove_variable'
and trigger.event.data.key is defined
%}
{{ dict(current.items() | rejectattr('0', 'eq', trigger.event.data.key)) }}
{% elif trigger.event.event_type == 'clear_variables' %}
{{ {} }}
{% else %}
{{ current }}
{% endif %}
You can set the value for the set_timestamp attribute to true if you want to add a timestamp for the event by default, this can be overridden when you actually store a variable.
If you set log_events to true the events on which the sensor was triggered will be logged in the logbook.
How to add a variable
The sensor uses event triggers to store the data, you can send a custom event as an automation or script action, or you can use developer tools > events to send it.
# example for an action in an automation
action:
- event: set_variable
event_data:
key: some_test
value: Some Value
set_timestamp: false
Event data parameters
| parameter | type | required | explanation |
|---|---|---|---|
| key | string | yes | the name of the variable |
| value | string | yes | the value which you want to store this kan be any kind of value. datetime objects will be stored as isoformat string |
| set_timestamp | boolean | no | Use this paramter to set the default timestamp setting used in the sensor |
Exemple of the attributes of the sensor after adding some variables
default_timestamp: true
log_events: false
variables:
test_without_timestamp: What time is it?
test_with_timestamp:
value: I know the time!
timestamp: '2022-10-02T20:19:41.713241+02:00'
some_list:
- item 1
- item 2
a_mapping:
fruit: banana
veggies: broccoli
friendly_name: Variables
How to retreive a variable.
To retreive a variable, you’ll need to use a template. The template differs for variables stored with or without a timestamp.
With timestamp
replace variable_key with the actual key used when adding the variable
{{ state_attr('sensor.variables', 'variables')['variable_key'].value }}
Without timestamp
replace variable_key with the actual key used when adding the variable
{{ state_attr('sensor.variables', 'variables')['variable_key'] }}
How to remove variables
You can send an event similar as when you added a variable.
action: # example for an action in an automation
- event: remove_variable
event_data:
key: some_test
You can remove all stored variables in one go by sending the clear_variables event without further event data.
let me check that when I’m back from holiday
I have noticed that firing set_variable events in my automations causes some errors. With the blocks responsible for firing these events disabled, there are no issues, so I’m pretty sure something must be off with the global Variables.
