[SOLVED] Combined transformations REGEX and MAP using HTTP binding

Add-ons Bindings
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1

Hi,
I have a device in my local network, which exposes its information for reading purposes via HTTP. The output is not structured (e.g. json or xml), but plain text and can be:

Device is ACTIVE

or

Device is DISABLED

I use the HTTP binding to read the message frequently:

String MyDevice_Status “Status” { http=“<[http://device-host/endpoint:5000:REGEX(.* ([A-Z]+))]”} }

This reads the “ACTIVE” or “DISABLED” into the item MyDevice_Status. Now I want to map the extracted string (ACTIVE or DISABLED) to a good practice item state (ON or OFF). I can use a mapping for this:

ACTIVE=ON
DISABLED=OFF
=UNKNOWN

However, I don’t see any possibility to combine MAP and REGEX in the item definition using the HTTP binding. I tried “chaining” them through

String MyDevice_Status “Status” { http=“<[http://device-host/endpoint:5000:REGEX(.* ([A-Z]+)):MAP(device.map)]”} }

which brings an error.

Is it possible to combine transformations REGEX and MAP inside the item definition using an HTTP binding?

2

Shot answer: no. It is not possible to “chain” transformations.

You solution will be a proxy item:
Make your HTTP item as proxy and create a switch:

String MyDevice_Status_Proxy “Status” { http="<[http://device-host/endpoint:5000:REGEX(.* ([A-Z]+))]"} }
Switch MyDevice_Status

and a rule:

rule "Proxy mydevice"
when
    Item MyDevice_Status_Proxy changed
then
    MyDevice_Status.postUpdate(transform("MAP", "device.map", MyDevice_Status_Proxy.state.toString))
end
1 Like
3

Thanks much for the quick reply! I thought about a similar solution. Follow up question:

A second endpoint at the device I mentioned exposes to write a state change to the device (switching something on or off). I want to combine the status (ON/OFF) in Device_Status along with an additional HTTP binding to post the state to the device downstream.

Something like:

String MyDevice_Status_Proxy "Proxy" { http="<[http://device-host/endpoint:5000:REGEX(.* ([A-Z]+))]"} }
Switch MyDevice_Status "Status" { http=">[ON:POST:http://device-host/another-endpoint?active] >[OFF:POST:http://device-host/another-endpoint?disabled]"}

Assuming your suggested rule above posting an update to the switch, will this work together with the HTTP binding?

4

No, now you need to use .sendCommand in order to pass the state to the binding:

rule "Proxy mydevice"
when
    Item MyDevice_Status_Proxy changed
then
    MyDevice_Status.sendCommand(transform("MAP", "device.map", MyDevice_Status_Proxy.state.toString))
end
1 Like
5

Will

sendCommand(..)

force the HTTP binding to issue the POST call?

6

Yes… That’s the difference between postUpdate and sendCommand
See:

7

Then I would say, in my case

postUpdate(..)

is the proper thing.

I’m reading the state from the device frequently, through MyDevice_Proxy (and its HTTP binding). If the state of the device has changed, I don’t want to write the same state back to the device.

8

Correct, in your case.
Please tick the solution post, thanks