Implement track_time_pattern in templates

source/_docs/configuration/templating.markdown

@@ -59,6 +59,7 @@ Extensions allow templates to access all of the Home Assistant specific states a
 - `state_attr('device_tracker.paulus', 'battery')` will return the value of the attribute or None if it doesn't exist.
 - `is_state_attr('device_tracker.paulus', 'battery', 40)` will test if the given entity attribute is the specified state (in this case, a numeric value). Note that the attribute can be `None` and you want to check if it is `None`, you need to use `state_attr('sensor.my_sensor', 'attr') == None`. 
 - `rate_limit` - limits re-renders of the template. Returns an empty string and accepts the same arguments as the Python `datetime.timedelta` function -- days, seconds, microseconds, milliseconds, minutes, hours, weeks.
+- `track_time_pattern` - Switch template updates to a specific time pattern. Returns an empty string and accepts the same arguments as [Time Pattern Triggers](/docs/automation/trigger/#time-pattern-trigger) along with either `None` or `off` to disable all template updates.
 <div class='note warning'>
 
   Avoid using `states.sensor.temperature.state`, instead use `states('sensor.temperature')`. It is strongly advised to use the `states()`, `is_state()`, `state_attr()` and `is_state_attr()` as much as possible, to avoid errors and error message when the entity isn't ready yet (e.g., during Home Assistant startup).

source/_integrations/binary_sensor.template.markdown

@@ -323,79 +323,69 @@ If the template accesses every state on the system or all states under a specifi
 
 ### Working without entities
 
-The `template` sensors are not limited to use attributes from other entities but can also work with [Home Assistant's template extensions](/docs/configuration/templating/#home-assistant-template-extensions). If the template includes some non-deterministic property such as time in its calculation, the result will not continually update, but will only update when some entity referenced by the template updates. 
+The `template` sensors are not limited to use attributes from other entities but can also work with [Home Assistant's template extensions](/docs/configuration/templating/#home-assistant-template-extensions). If the template does not include any entities, and references `now()` or `utcnow()`, by default it will be updated once per minute. If the template does not include any entities, `now()`, or `utcnow()`, the template will not update automaticlly.
 
-There's a couple of options to manage this issue. This first example creates a `sensor.time` from the [Time & Date](/integrations/time_date/) component which updates every minute, and the binary sensor is triggered by this updating. The binary sensor returns true if in the first half of the hour:
+The `track_time_pattern` directive can be used to control when the template should be updated.
+
+`track_time_pattern` accepts the same arguments as [Time Pattern Triggers](/docs/automation/trigger/#time-pattern-trigger) along with either `None` or `off` to disable all template updates.
+
+In the below example, the template will be updated on the half hour:
 
 {% raw %}
 ```yaml
-sensor:
-  - platform: time_date
-    display_options:
-      - 'time'
-
 binary_sensor:
   - platform: template
     sensors:
       half_hour:
-        value_template: '{{ (states("sensor.time")[3:] | int) < 30 }}'
+        value_template: '{{ track_time_pattern(minutes=30) }}{{ now() }}'
 ```
 {% endraw %}
 
-An alternative to this is to create an interval-based automation that calls the service `homeassistant.update_entity` for the entities requiring updates:
+In the case where the template should only be updated at the top of the hour:
 
 {% raw %}
 ```yaml
 binary_sensor:
 - platform: template
   sensors:
-    half_hour:
-      value_template: '{{ now().minute < 30 }}'
-
-automation:
-  - alias: 'Update half_hour'
-    trigger:
-      - platform: time_pattern
-        minutes: /30
-    action:
-      - service: homeassistant.update_entity
-        entity_id: binary_sensor.half_hour
+    in_the_midnight_hour:
+      value_template: >-
+        {{ track_time_pattern(hours=0) }}
+        {{ now().hour == 0 }}
 ```
 {% endraw %}
 
-In the case where the template should be updated every minute, just reading `states("sensor.time")` can achieve the desired result without the need to create an automation:
+In the case where the template should only be updated at 30 second mark for minutes divisible by 5:
 
 {% raw %}
 ```yaml
-sensor:
-  - platform: time_date
-    display_options:
-      - 'time'
-
 binary_sensor:
 - platform: template
   sensors:
-    minute_is_odd:
+    is_charging:
       value_template: >-
-        {% set dummy = states("sensor.time") %}
-        {{ now().minute % 2 == 1 }}
+        {{ track_time_pattern(minutes="/5", seconds=30) }}
+        {{ states("sensor.inflow_power") | float > 5 }}
 ```
 {% endraw %}
 
-A similar trick of ignoring the sensor value can be used with `states("sensor.date")` for templates that should update at midnight.
-The `time_date` sensors are always true so here we use `and` to ignore the result in a more condensed way:
+For more complex updates, automatic template updates can be disabled with `track_time_pattern(None)` and updates can be done manually by calling the `homeassistant.update_entity` service:
 
 {% raw %}
 ```yaml
-sensor:
-  - platform: time_date
-    display_options:
-      - 'date'
-
 binary_sensor:
 - platform: template
   sensors:
-    weekend:
-      value_template: {{ states("sensor.date") and now().isoweekday() > 5 }}
+    half_hour:
+      value_template: '{{ track_time_pattern(None) }}{{ now().minute < 30 }}'
+
+automation:
+  - alias: 'Update half_hour'
+    trigger:
+      - platform: time_pattern
+        minutes: /30
+    action:
+      - service: homeassistant.update_entity
+        entity_id: binary_sensor.half_hour
 ```
 {% endraw %}

source/_integrations/template.markdown

@@ -321,65 +321,23 @@ sensor:
 
 The `template` sensors are not limited to use attributes from other entities but can also work with [Home Assistant's template extensions](/docs/configuration/templating/#home-assistant-template-extensions).
 
-This template contains no entities that will trigger an update, so we add in a reference to the `sensor.date` sensor from the [Time & Date](/integrations/time_date/), which will update once a day.
+When a template contains no entities, and references `now()`, by default it will be updated once per minute. If the template does not include any entities, `now()`, or `utcnow()`, the template will not update automaticlly.
 
-{% raw %}
-
-```yaml
-sensor:
-  - platform: time_date
-    display_options:
-      - 'date'
-  - platform: template
-    sensors:
-      nonsmoker:
-        value_template: '{{ states('sensor.date') and (( as_timestamp(now()) - as_timestamp(strptime("06.07.2018", "%d.%m.%Y")) ) / 86400 ) | round(2) }}'
-        friendly_name: 'Not smoking'
-        unit_of_measurement: "Days"
-```
-
-{% endraw %}
-
-In this case it is also possible to convert the entity-less template above into one that will be updated automatically:
-
-{% raw %}
-
-````yaml
-sensor:
-  - platform: template
-    sensors:
-      nonsmoker:
-        value_template: "{{ (( as_timestamp(strptime(states('sensor.date'), '%Y-%m-%d')) - as_timestamp(strptime('06.07.2018', '%d.%m.%Y')) ) / 86400 ) | round(2) }}"
-        friendly_name: 'Not smoking'
-        unit_of_measurement: "Days"
-````
-
-{% endraw %}
-
-Useful entities to choose might be `sensor.date` which update once per day or `sensor.time`, which updates once per minute.  
-Please note that the resulting template will be evaluated by Home Assistant state engine on every state change of these sensors, which in case of `sensor.time` happens every minute and might have a negative impact on performance.
+The `track_time_pattern` directive can be used to control when the template should be updated.
 
-An alternative to this is to create an interval-based automation that calls the service `homeassistant.update_entity` for the entities requiring updates. This modified example updates every 5 minutes:
+The below example will update once per day at `00:00:00`:
 
 {% raw %}
 
 ```yaml
-sensor:
   - platform: template
     sensors:
       nonsmoker:
-        value_template: '{{ (( as_timestamp(now()) - as_timestamp(strptime("06.07.2018", "%d.%m.%Y")) ) / 86400 ) | round(2) }}'
+        value_template: '{{ track_time_pattern(hours=0, minutes=0, seconds=0) }}{{(( as_timestamp(now()) - as_timestamp(strptime("06.07.2018", "%d.%m.%Y")) ) / 86400 ) | round(2) }}'
         friendly_name: 'Not smoking'
         unit_of_measurement: "Days"
-
-automation:
-  - alias: 'nonsmoker_update'
-    trigger:
-      - platform: time_pattern
-        minutes: '/5'
-    action:
-      - service: homeassistant.update_entity
-        entity_id: sensor.nonsmoker
 ```
 
 {% endraw %}
+
+See [Working without entities](/integrations/binary_sensor.template/#working-without-entities) in the Template Binary Sensor integration for additional examples.