How to Capture an Attribute Changing By a Specific Amount

Third party integrations Node-RED
1

I would like to capture an event when a light’s brightness attribute changes by a specific amount (in my case, the brightness attribute changes by more than 10). If figured that the best way to do this would be through a JSONata expression that compares the current and previous attributes of the light. I have tried to do this inside both the Event State and Trigger nodes themselves, and I have also tried passing the light change event to a switch node to do the comparison (even though this is slightly more cluttered).

Either way, I just can’t seem to get the expression to evaluate correctly, and I don’t know why. I also removed $entity() and $prevEntity() references after they kept throwing error messages. I am stuck with what seems like an easy request. Can someone help me?

Here is my latest attempt:

[{"id":"a4f0c644.08d6a8","type":"debug","z":"705864b.793309c","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","x":845,"y":435,"wires":[]},{"id":"47e02624.0570d8","type":"trigger-state","z":"705864b.793309c","name":"Light Already On and Attribute Changed","server":"af006389.170db","entityid":"light.","entityidfiltertype":"substring","debugenabled":false,"constraints":[{"id":"k7xcfhszxpc","targetType":"this_entity","targetValue":"","propertyType":"current_state","propertyValue":"new_state.state","comparatorType":"is","comparatorValueDatatype":"str","comparatorValue":"on"},{"id":"tz9nqyp7rk","targetType":"this_entity","targetValue":"","propertyType":"previous_state","propertyValue":"old_state.state","comparatorType":"is","comparatorValueDatatype":"str","comparatorValue":"on"}],"constraintsmustmatch":"all","outputs":2,"customoutputs":[],"outputinitially":false,"state_type":"str","x":265,"y":435,"wires":[["b4996c7.c56f49"],[]]},{"id":"b4996c7.c56f49","type":"switch","z":"705864b.793309c","name":"Brightness Increased By 10 Or More","property":"$abs(msg.data.new_state.attributes.brightness - msg.data.new_state.attributes.brightness)","propertyType":"jsonata","rules":[{"t":"gt","v":"10","vt":"num"}],"checkall":"true","repair":false,"outputs":1,"x":615,"y":435,"wires":[["a4f0c644.08d6a8"]]},{"id":"af006389.170db","type":"server","z":"","name":"Home Assistant"}]

Thank you!

2

Maybe you can also try the RBE node (report by exception) which you can set to only report if changes are higher / lower than X

3

Looks like I had an incorrect path to the brightness attribute in my switch node in the above example. The following version works:

[{"id":"705864b.793309c","type":"tab","label":"Prototypes","disabled":false,"info":""},{"id":"fffa9f27.8f564","type":"delay","z":"705864b.793309c","name":"","pauseType":"delay","timeout":"2","timeoutUnits":"seconds","rate":"1","nbRateUnits":"1","rateUnits":"second","randomFirst":"1","randomLast":"5","randomUnits":"seconds","drop":false,"x":615,"y":135,"wires":[["dd4e70fc.6d4a4"]]},{"id":"a00c0fd5.39ae1","type":"change","z":"705864b.793309c","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"{\"domain\":\"hue\",\"service\":\"hue_activate_scene\",\"data\":{\"group_name\":\"Stairs Ceiling\",\"scene_name\":\"Bright\"}}","tot":"json"}],"action":"","property":"","from":"","to":"","reg":false,"x":195,"y":225,"wires":[["823498ea.6c9df8"]]},{"id":"c9784bd2.70b708","type":"inject","z":"705864b.793309c","name":"","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":150,"y":150,"wires":[["a00c0fd5.39ae1"]]},{"id":"69a4268.5436ad8","type":"splitter","z":"705864b.793309c","name":"","property":"payload","x":320,"y":300,"wires":[[]]},{"id":"dd4e70fc.6d4a4","type":"api-call-service","z":"705864b.793309c","name":"Call Service","server":"af006389.170db","version":1,"service_domain":"","service":"","entityId":"","data":"","dataType":"json","mergecontext":"","output_location":"","output_location_type":"none","mustacheAltTags":false,"x":655,"y":30,"wires":[["823498ea.6c9df8"]]},{"id":"414ed521.d0b2dc","type":"debug","z":"705864b.793309c","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","x":485,"y":195,"wires":[]},{"id":"823498ea.6c9df8","type":"Serial Iterator","z":"705864b.793309c","name":"","property":"payload","inputFlow":"input","saveOutput":0,"recursive":0,"storeId":0,"x":420,"y":105,"wires":[["fffa9f27.8f564","414ed521.d0b2dc"],[]]},{"id":"282298e5.82f0a8","type":"trigger-state","z":"705864b.793309c","name":"A Light's Brightness Changed","server":"af006389.170db","entityid":"light.","entityidfiltertype":"substring","debugenabled":false,"constraints":[{"id":"k7xcfhszxpc","targetType":"this_entity","targetValue":"","propertyType":"current_state","propertyValue":"new_state.state","comparatorType":"is","comparatorValueDatatype":"str","comparatorValue":"on"},{"id":"tz9nqyp7rk","targetType":"this_entity","targetValue":"","propertyType":"previous_state","propertyValue":"old_state.state","comparatorType":"is","comparatorValueDatatype":"str","comparatorValue":"on"},{"id":"s5naj5cphd","targetType":"this_entity","targetValue":"","propertyType":"property","propertyValue":"new_state.attributes.brightness","comparatorType":"is_not","comparatorValueDatatype":"entity","comparatorValue":"old_state.attributes.brightness"}],"constraintsmustmatch":"all","outputs":2,"customoutputs":[],"outputinitially":false,"state_type":"str","x":240,"y":555,"wires":[["79ffc279.32037c"],[]]},{"id":"79ffc279.32037c","type":"debug","z":"705864b.793309c","name":"","active":false,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","x":468,"y":554,"wires":[]},{"id":"a9ef67b0.8cb168","type":"trigger-state","z":"705864b.793309c","name":"A Light's Color Temperature Changed","server":"af006389.170db","entityid":"light.","entityidfiltertype":"substring","debugenabled":false,"constraints":[{"id":"k7xcfhszxpc","targetType":"this_entity","targetValue":"","propertyType":"current_state","propertyValue":"new_state.state","comparatorType":"is","comparatorValueDatatype":"str","comparatorValue":"on"},{"id":"tz9nqyp7rk","targetType":"this_entity","targetValue":"","propertyType":"previous_state","propertyValue":"old_state.state","comparatorType":"is","comparatorValueDatatype":"str","comparatorValue":"on"},{"id":"kzp7ebw1no","targetType":"this_entity","targetValue":"","propertyType":"property","propertyValue":"new_state.attributes.color_temp","comparatorType":"is_not","comparatorValueDatatype":"entity","comparatorValue":"old_state.attributes.color_temp"}],"constraintsmustmatch":"all","outputs":2,"customoutputs":[],"outputinitially":false,"state_type":"str","x":255,"y":615,"wires":[["79ffc279.32037c"],[]]},{"id":"83e2f725.5160f8","type":"trigger-state","z":"705864b.793309c","name":"A Light's Brightness Changed","server":"af006389.170db","entityid":"light.","entityidfiltertype":"substring","debugenabled":false,"constraints":[{"id":"k7xcfhszxpc","targetType":"this_entity","targetValue":"","propertyType":"current_state","propertyValue":"new_state.state","comparatorType":"is","comparatorValueDatatype":"str","comparatorValue":"on"},{"id":"tz9nqyp7rk","targetType":"this_entity","targetValue":"","propertyType":"previous_state","propertyValue":"old_state.state","comparatorType":"is","comparatorValueDatatype":"str","comparatorValue":"on"},{"id":"s5naj5cphd","targetType":"this_entity","targetValue":"","propertyType":"property","propertyValue":"new_state.attributes.brightness","comparatorType":"is_not","comparatorValueDatatype":"entity","comparatorValue":"old_state.attributes.brightness"}],"constraintsmustmatch":"all","outputs":2,"customoutputs":[],"outputinitially":false,"state_type":"str","x":283,"y":810,"wires":[[],[]]},{"id":"37be4f9a.cd9b3","type":"server-state-changed","z":"705864b.793309c","name":"","server":"ef067c6f.620e6","version":0,"entityidfilter":"^climate\\.+","entityidfiltertype":"regex","outputinitially":false,"state_type":"str","haltifstate":"","halt_if_type":"str","halt_if_compare":"is","outputs":1,"output_only_on_state_change":false,"x":540,"y":915,"wires":[["ee37bfd3.68657"]]},{"id":"ee37bfd3.68657","type":"switch","z":"705864b.793309c","name":"","property":"data.attributes.temperature","propertyType":"msg","rules":[{"t":"lt","v":"data.attributes.current_temperature","vt":"msg"}],"checkall":"true","repair":false,"outputs":1,"x":734,"y":915,"wires":[["929aa496.93d598"]]},{"id":"929aa496.93d598","type":"debug","z":"705864b.793309c","name":"Turn on boiler","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","x":892,"y":915,"wires":[]},{"id":"a41f35fe.de4168","type":"server-state-changed","z":"705864b.793309c","name":"Light Is Already On and Attribute Changed","server":"af006389.170db","version":1,"entityidfilter":"light.","entityidfiltertype":"substring","outputinitially":false,"state_type":"str","haltifstate":"$entity().state = \"on\"","halt_if_type":"jsonata","halt_if_compare":"jsonata","outputs":2,"output_only_on_state_change":true,"x":265,"y":495,"wires":[[],[]]},{"id":"a4f0c644.08d6a8","type":"debug","z":"705864b.793309c","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","x":845,"y":435,"wires":[]},{"id":"47e02624.0570d8","type":"trigger-state","z":"705864b.793309c","name":"Light Already On and Attribute Changed","server":"af006389.170db","entityid":"light.","entityidfiltertype":"substring","debugenabled":false,"constraints":[{"id":"k7xcfhszxpc","targetType":"this_entity","targetValue":"","propertyType":"current_state","propertyValue":"new_state.state","comparatorType":"is","comparatorValueDatatype":"str","comparatorValue":"on"},{"id":"tz9nqyp7rk","targetType":"this_entity","targetValue":"","propertyType":"previous_state","propertyValue":"old_state.state","comparatorType":"is","comparatorValueDatatype":"str","comparatorValue":"on"}],"constraintsmustmatch":"all","outputs":2,"customoutputs":[],"outputinitially":false,"state_type":"str","x":265,"y":435,"wires":[["b4996c7.c56f49"],[]]},{"id":"b4996c7.c56f49","type":"switch","z":"705864b.793309c","name":"Brightness Changed By 10 Or More","property":"$abs(msg.data.event.new_state.attributes.brightness - msg.data.event.old_state.attributes.brightness)","propertyType":"jsonata","rules":[{"t":"gt","v":"10","vt":"num"}],"checkall":"true","repair":false,"outputs":1,"x":605,"y":435,"wires":[["a4f0c644.08d6a8"]]},{"id":"af006389.170db","type":"server","z":"","name":"Home Assistant"}]

However, I would still prefer to collapse this all into a single event node (without the corresponding switch node) if possible. Suggestions welcome!

4

$abs($entity().attributes.brightness - $prevEntity().attributes.brightness) > 10

5

Thank you @kermit, but where would this expression sit in the flow? In one of the event nodes? If so, which field?

6 
[{"id":"e8610508.f6c838","type":"server-state-changed","z":"e5ff79f7.039488","name":"Light Is Already On and Attribute Changed","version":1,"entityidfilter":"light.","entityidfiltertype":"substring","outputinitially":false,"state_type":"str","haltifstate":"$entity().state = \"on\" and $prevEntity().state = \"on\" and $abs($entity().attributes.brightness - $prevEntity().attributes.brightness) > 10","halt_if_type":"jsonata","halt_if_compare":"jsonata","outputs":2,"output_only_on_state_change":true,"x":265,"y":495,"wires":[[],[]]}]
7

@kermit, I gave that a try, but the event does not get captured. Does the “events: state” node capture attribute changes when the state itself doesn’t actually change? From my tests, it doesn’t appear to.

On the other hand, “trigger: state” does capture attribute changes without a state change, but the node configuration options are different. Is there a way to create a constraint that compares the new.old brightness attributes?

Thank you for your help.

8

In the Events: state node uncheck Output only on state change

9

:man_facepalming: Of course! I wasn’t sure what the box did…now I know. Again, thank you for your help, and for your great work on this integration. It is very much appreciated!