I thought I could insert the values for longitude, latitude and altitude as comma separated values into a location item by inserting the following per JSONPath at the Incoming Value Transformations item:
Unfortunately, I don’t think it’s possible to do this in one go. You’ll have to extract each parameter into separate Items, and then combine using a rule.
It means e.g. [$.longitude, $.latitude, $.altitude]
will not do, you need to tell it which transformation service to use JSONPATH:[$.longitude, $.latitude, $.altitude]
or JSONPATH:this∩JSONPATH:that
which will satisfy the syntax, but as you have found will not do what you want as the transformation service is limited to single-string answers, and chaining with ∩ pipes one output into the next input.
As already suggested, use JS instead to extract and manipulate into the single comma string that you want.