Hi there,
Using MQTT Engine, im receiving an array of string, which I want to display only one of the string from the array. Im trying to index the array by using "[2]", but it displays all the strings in the array anyway. How can i display only ie. number 2?
The MQTT variable:
Indexing and displaying the array, still gives all values.
Any ideas? 
Have you tried using a script transform on the value? Perhaps something like list(value)[1] would work.
It's probably nothing to do with the problem but you've shown the Hops names variable content but your binding is for Hops use.
I've created a string array memory tag and can access each element as you are without difficulty. Can you show us the contents of Hops use?
You've created a Script Transform. Justin's given you an Expression Transform.
Remove the [1] from your tag path.
Delete the script transform.
Create an expression transform.
Paste his code straight in and that's it.
Think of expressions as being like Excel functions. It's not a program script but rather one or more functions or operations on variables and it just returns one result (or result set).
Hover over the Error_Configuration error to read what the problem is.
Sorry, I'm having a bad day. list() is a script function, not an expression function. Your first attempt was right but Justin, I think, missed the { } braces. Try modifying the script to,
list({value})[1]
{value} is what's passed into the transform from the previous operation.
I modified my previous post. It may be better to wait on someone else to respond!
Question for anyone else reading the thread:
Vidar's MQTT tags display in Tag Browser are displayed as an array / list like this:
When I created a string array for testing it shows up like this:
Can you explain why?
Thats strange... Any chance that this has something to do with MQTT to do? Im publishing data from Nodered/MQTT. The data from nodered looks like this (array):
Then, it is sent via MQTT node. Not sure what is done with the data inside this node. Maybe its sent as 1 complete string, instead of array?
Or maybe not, when i subscribe to this topic it is displayed as array:
I would expect this expression transform to work:
{value}[1]
Check the data type on the actual tag you're getting. I suspect it's passing it as a JSON string and not an array.
Edit: If this is the case, you'll need something like:
jsonGet({value},'[1]')
Thanks, not sure where to check which data type is recieved...
No luck with the jsonGet either... 
EDIT:
Actually, this worked!
Glad it worked for you.
I just realized I should have left off the return (I was mixing up expressions with scripting there for a bit). I'll edit it so no one else gets confused by it either.
Usually there's a 3rd column that shows what your datatype is that I'm not seeing in your screenshot.
