Using a flow variable in the home assistant call service node


I need some help with the correct syntax to use. I am trying to set my thermostat to a value I have stored in a flow variable - the variable is called TargetHigh - I have tried using the following but get an error -

I am pretty sure I just have the syntax wrong, if I replace the word TargetHigh with a value - for example 23 the code works and the thermostat is set to 23.
Many Thanks

Using JSONata try.
{"temperature": $flowContext("TargetHigh")}

It gives me the following error -
"Call-service error. must contain at least one of temperature, target_temp_high, target_temp_low."

Have you set the value 23 to flow context "TargetHigh"
show us the context variable is set, and is in the same flow tab.


Here is a screen shot of the variable getting set, it's in the same flow - the current value is 20.4 which is shown in the debug window (I don't know how else to show you - sorry I'm quite new at this)