[jinja] Empty string result when binding is missing

[antroids]

I'm creating an implementation of climate platform for mqtt.homeassistant binding, but found a side issue.
Variable used in state_template can be missing in the state, but Jinja returns the empty string, that considered as valid value.

Expected Behavior

Thing state should not be updated when variable from state_template is missing in the state.

Current Behavior

20:26:16.995 [WARN ] [hab.binding.mqtt.generic.ChannelState] - Command '' not supported by type 'OnOffValue': No enum constant org.openhab.core.library.types.OnOffType.`

Payload:
'{"auto_lock":"AUTO","away_mode":"OFF","away_preset_days":1,"away_preset_temperature":15,"battery_low":false,"boost_time":300,"child_lock":"UNLOCK","comfort_temperature":20,"current_heating_setpoint":20,"eco_temperature":15,"force":"normal","holidays":[{"hour":6,"minute":0,"temperature":20},{"hour":8,"minute":0,"temperature":15},{"hour":11,"minute":30,"temperature":15},{"hour":12,"minute":30,"temperature":15},{"hour":17,"minute":30,"temperature":20},{"hour":22,"minute":0,"temperature":15}],"linkquality":70,"local_temperature":26,"local_temperature_calibration":-1,"max_temperature":35,"min_temperature":5,"position":0,"preset":"schedule","system_mode":"auto","update":{"state":"idle"},"update_available":false,"week":"5+2","window_detection":"OFF","window_detection_params":{"minutes":10,"temperature":5},"workdays":[{"hour":6,"minute":0,"temperature":20},{"hour":8,"minute":0,"temperature":15},{"hour":11,"minute":30,"temperature":15},{"hour":12,"minute":30,"temperature":15},{"hour":17,"minute":30,"temperature":20},{"hour":22,"minute":0,"temperature":15}]}'

Template:
{{ value_json.valve_detection }}

Possible Solution

Try this config option: com.hubspot.jinjava.JinjavaConfig#isFailOnUnknownTokens

Steps to Reproduce (for Bugs)

1. Add the template to OnOff MQTT channel with binding, that missing in state.
2. Publish MQTT message.

Your Environment

• Version used: openHAB 3.0.1

[antroids]

Also reported to zigbee2mqtt project issue with missing properties in state payload.

[Rossko57]

When user-defined transformations are involved, common practice is to chain a REGEX that looks for presence of property to another transformation e.g. JSONPATH extracting property. If the REGEX fails, the JSONPATH is not run and so missing field WARNS and empty updates avoided.

[antroids]

Sounds like quick fix. These transformations are defined by mqtt topic with Home Assistant configuration, they can be little complexity. Not sure that regexp can be generated to cover jinja syntax. For example:
{"action_template":"{% set values = {'idle':'off','heat':'heating','cool':'cooling','fan only':'fan'} %}{{ values[value_json.running_state] }}","action_topic":"zigbee2mqtt/th1"}

[antroids]

I've checked the option com.hubspot.jinjava.JinjavaConfig#isFailOnUnknownTokens.
In Jinjava 2.5.0 it works only for root variables, and ignores map structures and java beans.
To support Jinja transformation in correct way, Jinjava must be upgraded to last version.

Jinjava 2.5.0 just ignores missing map keys, so we don't know whether state is invalid or empty:

• binding: ["value_json": "val"], pattern: "{{ value_json.val }}", result: "val"
• binding: ["value_json": "val"], pattern: "{{ value_json.asd }}", result: ""
• binding: ["value_json": ["val":""]], pattern: "{{ value_json.val }}", result: ""
• binding: ["value_json": "val"], pattern: "{{ value_json.val is defined }}", result: true
• binding: ["value_json": "val"], pattern: "{{ value_json.asd is defined }}", result: false

Jinvava 2.5.7 works well:

• binding: ["value_json": "val"], pattern: "{{ value_json.val }}", result: "val"
• binding: ["value_json": "val"], pattern: "{{ value_json.asd }}", result: UnknownTokenException
• binding: ["value_json": ["val":""]], pattern: "{{ value_json.val }}", result: ""
• binding: ["value_json": "val"], pattern: "{{ value_json.val is defined }}", result: true
• binding: ["value_json": "val"], pattern: "{{ value_json.asd is defined }}", result: false

Looks like dependency version cannot be updated just in addon's pom, and I need to upload it to the OpenHAB Repository first? How can I do this?

[openhab-bot]

This issue has been mentioned on openHAB Community. There might be relevant details there:

https://community.openhab.org/t/update-version-of-osgified-dependency/120768/1