State value for "Custom Template Sensor" gets automatically reset to empty

Configuration
1

Hello, I followed this thread:

and created a new “Custom Template Sensor” successfully.

I’m able to update the value of the state for this sensor fine:

curl -X POST -H "Authorization: Bearer LONG_LIVED_ACCESS_TOKEN" \
       -H "Content-Type: application/json" \
       -d '{"state": "29", "attributes": {"unit_of_measurement": "°C", "friendly_name": "Outdoor Temperature"}}' \
       https://{my-homeassistant-url}/api/states/sensor.outdoor_temperature

However, the state gets reset back to empty a few seconds later:

2019-08-10 19:01:39 DEBUG (MainThread) [homeassistant.components.websocket_api.http.connection.2901368752] Sending {'id': 2, 'type': 'event', 'event': <Event state_changed[L]: entity_id=sun.sun, old_state=<state sun.sun=above_horizon; next_dawn=2019-08-11T02:07:35+00:00, next_dusk=2019-08-10T18:49:52+00:00, next_midnight=2019-08-10T22:27:29+00:00, next_noon=2019-08-11T10:27:32+00:00, next_rising=2019-08-11T02:50:03+00:00, next_setting=2019-08-10T18:07:07+00:00, elevation=16.78, azimuth=273.07, rising=False, friendly_name=Sun @ 2019-08-10T18:49:36.775854+03:00>, new_state=<state sun.sun=above_horizon; next_dawn=2019-08-11T02:07:35+00:00, next_dusk=2019-08-10T18:49:52+00:00, next_midnight=2019-08-10T22:27:29+00:00, next_noon=2019-08-11T10:27:32+00:00, next_rising=2019-08-11T02:50:03+00:00, next_setting=2019-08-10T18:07:07+00:00, elevation=16.2, azimuth=273.88, rising=False, friendly_name=Sun @ 2019-08-10T18:49:36.775854+03:00>>}
2019-08-10 19:01:39 DEBUG (MainThread) [homeassistant.core] Bus:Handling <Event state_changed[L]: entity_id=sensor.outdoor_temperature, old_state=<state sensor.outdoor_temperature=; unit_of_measurement=°C, friendly_name=Outdoor Temperature, icon=mdi:thermometer @ 2019-08-10T19:01:26.011035+03:00>, new_state=<state sensor.outdoor_temperature=29; unit_of_measurement=°C, friendly_name=Outdoor Temperature @ 2019-08-10T19:01:39.812520+03:00>>
2019-08-10 19:01:39 DEBUG (MainThread) [homeassistant.components.websocket_api.http.connection.2901368752] Sending {'id': 2, 'type': 'event', 'event': <Event state_changed[L]: entity_id=sensor.outdoor_temperature, old_state=<state sensor.outdoor_temperature=; unit_of_measurement=°C, friendly_name=Outdoor Temperature, icon=mdi:thermometer @ 2019-08-10T19:01:26.011035+03:00>, new_state=<state sensor.outdoor_temperature=29; unit_of_measurement=°C, friendly_name=Outdoor Temperature @ 2019-08-10T19:01:39.812520+03:00>>}

2019-08-10 19:01:56 DEBUG (MainThread) [homeassistant.core] Bus:Handling <Event state_changed[L]: entity_id=sensor.outdoor_temperature, old_state=<state sensor.outdoor_temperature=29; unit_of_measurement=°C, friendly_name=Outdoor Temperature @ 2019-08-10T19:01:39.812520+03:00>, new_state=<state sensor.outdoor_temperature=; unit_of_measurement=°C, friendly_name=Outdoor Temperature, icon=mdi:thermometer @ 2019-08-10T19:01:56.014998+03:00>>
2019-08-10 19:01:56 DEBUG (MainThread) [homeassistant.components.websocket_api.http.connection.2901368752] Sending {'id': 2, 'type': 'event', 'event': <Event state_changed[L]: entity_id=sensor.outdoor_temperature, old_state=<state sensor.outdoor_temperature=29; unit_of_measurement=°C, friendly_name=Outdoor Temperature @ 2019-08-10T19:01:39.812520+03:00>, new_state=<state sensor.outdoor_temperature=; unit_of_measurement=°C, friendly_name=Outdoor Temperature, icon=mdi:thermometer @ 2019-08-10T19:01:56.014998+03:00>>}

I chart for this sensor in the “History” section is just a lot of dots / discrete values rather than a continuous line.

It doesn’t look right to me and any insight into what might be happening here is very welcome.

2

Assuming the values for the sensor come only from your curl POSTs, then you should not use a template sensor for this. Rather you should use an HTTP Sensor (which requires no configuration entry and is simply created when the POST is received.)

3

@pnbruckner, thanks for the message. Indeed HTTP sensor seems to be fit for my use-case, I’ll give it a go!.

4

OK, so @pnbruckner thanks again, I now understand what was happening. (I only started to use HA a week ago).
I created a “Custom Template Sensor”, but then I made an HTTP post as if my sensor was “HTTP sensor”. I actually thought that I’m updating my “Custom Template Sensor”, but perhaps each time a new HTTP Sensor was created and deleted or something like that. Or at least a clash of some sort between the “Custom Template Sensor” and "“HTTP Sensor”.

Anyway, I deleted the “Custom Template Sensors” from Integration and kept posting new values for the HTTP sensor - it all looks normal now.

I also need to check if the historical sensor values would disappear each time I restart HA, as I read “The sensor will then exist as long as Home Assistant is running. After a restart of Home Assistant the sensor will be gone until it is triggered again.”

5

Just to add - historical values do not disappear when I restart HA, so this solution (HTTP Sensor) works for me fine. Thanks.