Help with creating a dynamic list of tripped sensors

General
1

I'm attempting to create a list of contact sensors which are in the open state.

For example I have a node which returns the state of sensor XYZ. So if the payload is "open", the text "XYZ" is added to the string/list which I can do (each addition is delineated with a new line).

Conversely, if the state of XYZ changes to closed I want to be able to search for and delete "XYZ" from the string, and this part I'm not sure how to to achieve.

Any help/pointers gratefully received! String manipulation unfortunately is not one of my coding strengths.

1 Like
2

It would be easier to give some advice if you tell us how the data structure looks like. I assume the list is an array but if you decided to store data in an object then the code to achieve what you want would be different.

3

I see, thanks. To be honest I haven't given thought to the structure of the list. The intention is to be able to export a list of what sensors are "open" at any one time in the simplest possible way. The number of devices that would likely be populating the array/list at any time would be small (10 at most).

I'll give it some more thought to flesh it out further.

4

That is not the ideal way to achieve what you want.

Ideally you would store the state of the item and then build a string based on the state.

e.g. you could store the sensors values an array like this...

[
  { "name": "sensor 1", "state": false },
  { "name": "sensor 2", "state": true },
  { "name": "sensor 3", "state": true }, 
]

or an object like this...

{
 "Sensor 1": false,
 "Sensor 2": true,
 "Sensor 3": true
}

With an array, you could build a status string like this...

var offSensors = sensors.filter(e => e.state == false).map(e=>e.name).join(",");
//returns  'sensor 1'

var onSensors = sensors.filter(e => e.state == true).map(e=>e.name).join(",");
//returns  'sensor 2,sensor 3'

However, to update a value in the array is a bit harder (much easier with an object) so that is what i will demo...


Store sensors states in an object...

Premise...

Store a single value for each sensor named by msg.topic in an object named sensors in a flow context variable.

  • When updating a state in flow context, msg.topic must hold the sensor name and msg.payload must have the sensor value
  • Demo assumes msg.payload will be boolean (true or false)

Example data...

{
 "Sensor 1": false,
 "Sensor 2": true,
 "Sensor 3": true
}

//adding / updating a sensors value

var sensors = flow.get("sensors") || {};   //get the sensors state from flow context
var sensorName = msg.topic;                //get sensor name from incoming msg
sensors[sensorName] = msg.payload;         //store value under a key in the sensors object 
flow.set("sensors", sensors);              //update the flow context

getting a string of on or off sensors...

var sensors = flow.get("sensors") || {}; //get the sensors state from flow context

msg.payload = {}; //prepare the payload as an object, ready for the off and on strings

msg.payload.offSensors = Object.entries(sensors).filter(e => e[1] == false).map(e=>e[0]).join(",");
//return example  'sensor 1'

msg.payload.onSensors = Object.entries(sensors).filter(e => e[1] == true).map(e=>e[0]).join(",");
//return example 'sensor 2,sensor 3'

return msg;
2 Likes
5

Wow - thanks for that, it will keep me occupied for a fair few days working through it!

6

What is it being exported to and what use will then be made of it? The answer to that will influence which way is best.

7

Thanks Steve - that code works great!

@Colin, @Andrei FYI the output is being sent to my hubitat hub as a list of open contact sensors for display on a tablet dashboard. As display space is at a premium I wanted to just show a list of open sensors rather than create a whole bunch of device tiles to show status (most of them will be closed at any one time anyway)

8

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