A couple of people asked for a use case/examples of how you might use JSONata within the HA Nodes. So here are several random examples I have come up with. If you have examples of your own please post them so we can learn from each other.
Reference this post for details of functions added to JSONata expressions for the HA nodes.
There are many ways to accomplish what these examples show not using JSONata. JSONata just gives you another tool in your toolbox.
https://docs.jsonata.org
http://try.jsonata.org
Example #1
A remote with a button that when clicked it increases the brightness of a given light by an amount that is set from an input_number inside Home Assistant.
[{"id":"86cbf80d.5a9cf8","type":"api-call-service","z":"83fb2374.5839d","name":"","version":1,"service_domain":"light","service":"turn_on","entityId":"light.kitchen","data":"{\"brightness\": $min([$entities(\"light.kitchen\").attributes.brightness + $entities(\"input_number.brightness\").state, 255])}","dataType":"jsonata","mergecontext":"","output_location":"payload","output_location_type":"msg","mustacheAltTags":false,"x":426,"y":416,"wires":[[]]},{"id":"8aad6643.9ee7a8","type":"server-state-changed","z":"83fb2374.5839d","name":"Remote Button","version":1,"entityidfilter":"sensor.button","entityidfiltertype":"exact","outputinitially":false,"state_type":"str","haltifstate":"","halt_if_type":"str","halt_if_compare":"is","outputs":1,"output_only_on_state_change":true,"x":224,"y":416,"wires":[["86cbf80d.5a9cf8"]]}]
JSONata expression in the call-service node
{
"brightness": $min(
[
$entities("light.kitchen").attributes.brightness + $entities("input_number.brightness").state,
255
]
)
}
Example #2
Get notified when light or switch is left on when you leave. This a remake of Example #1 from this post showing how to manipulate entities and get the desired output.
[{"id":"8420cd3d.051ac","type":"trigger-state","z":"83fb2374.5839d","name":"Left Home","entityid":"device_tracker.jason","entityidfiltertype":"exact","debugenabled":false,"constraints":[{"id":"9i2c9sz7d3e","targetType":"this_entity","targetValue":"","propertyType":"previous_state","propertyValue":"old_state.state","comparatorType":"is","comparatorValueDatatype":"str","comparatorValue":"home"},{"id":"3h3lghs8xsm","targetType":"this_entity","targetValue":"","propertyType":"current_state","propertyValue":"new_state.state","comparatorType":"is","comparatorValueDatatype":"str","comparatorValue":"not_home"}],"constraintsmustmatch":"all","outputs":2,"customoutputs":[],"outputinitially":false,"state_type":"str","x":214,"y":240,"wires":[["888034a3.b642c8"],[]]},{"id":"888034a3.b642c8","type":"api-call-service","z":"83fb2374.5839d","name":"Notify","version":1,"service_domain":"notify","service":"android_jason","entityId":"","data":"{\t \"message\": \"The \" & $join($entities().*[state = \"on\" and entity_id ~> /^light|^switch/].attributes.friendly_name, \", \") & \" are on.\",\t \"title\": \"Left On\"\t}","dataType":"jsonata","mergecontext":"","output_location":"payload","output_location_type":"msg","mustacheAltTags":false,"x":370,"y":240,"wires":[[]]}]
This is same as above but uses an event:state node and shows how to use the $entity() and $prevEntity() functions to compare states.
[{"id":"cb25c8d7.881688","type":"server-state-changed","z":"83fb2374.5839d","name":"Left Home","version":1,"entityidfilter":"person.jason","entityidfiltertype":"exact","outputinitially":false,"state_type":"str","haltifstate":"$entity().state != $prevEntity().state","halt_if_type":"jsonata","halt_if_compare":"jsonata","outputs":2,"output_only_on_state_change":true,"x":204,"y":352,"wires":[["b48e8249.ad09f"],[]]},{"id":"b48e8249.ad09f","type":"api-call-service","z":"83fb2374.5839d","name":"Notify","version":1,"service_domain":"notify","service":"android_jason","entityId":"","data":"{\t \"message\": \"The \" & $join($entities().*[state = \"on\" and entity_id ~> /^light|^switch/].attributes.friendly_name, \", \") & \" are on.\",\t \"title\": \"Left Open\"\t}","dataType":"jsonata","mergecontext":"","output_location":"payload","output_location_type":"msg","mustacheAltTags":false,"x":354,"y":352,"wires":[[]]}]
Event-State Node:
$entity().state != $prevEntity().state
Call-Service Node:
{
"message": "The " & $join($entities().*[state = "on" and entity_id ~> /^light|^switch/].attributes.friendly_name, ", ") & " are on.",
"title": "Left Open"
}
Example #3
The trigger-state node is great if you have several conditions you want to check for but it doesn’t allow you to use OR checks. Using a JSONata expression with an event:state node will allow you to fill this gap.
Motion sensor at the front door triggers and have a text to speech notification be sent if at least one person is home.
[{"id":"114a7e82.282431","type":"server-state-changed","z":"fac037bf.a42d78","name":"Motion Front Door","version":1,"entityidfilter":"binary_sensor.front_door","entityidfiltertype":"exact","outputinitially":false,"state_type":"str","haltifstate":"$entity().state = \"on\" and (\t $entities(\"person.person1\").state = \"home\" or $entities(\"person.person2\").state = \"home\"\t)","halt_if_type":"jsonata","halt_if_compare":"jsonata","outputs":2,"output_only_on_state_change":true,"x":218,"y":1040,"wires":[["8c84fdde.9770f"],[]]},{"id":"8c84fdde.9770f","type":"api-call-service","z":"fac037bf.a42d78","name":"TTS Motion","version":1,"service_domain":"tts","service":"google_say","entityId":"","data":"{\"message\": \"Movement at the front door.\"}","dataType":"json","mergecontext":"","output_location":"","output_location_type":"none","mustacheAltTags":false,"x":406,"y":1040,"wires":[[]]}]
$entity().state = "on" and (
$entities("person.person1").state = "home" or $entities("person.person2").state = "home"
)