Passing coordinates into device_tracker.see as variables

I am trying to pass the gps coordinates into device_tracker.see and I can get it to work with hard coded values but I cannot for the life of me work out the syntax using variables and a data template. The variables are being picked up in the automation OK but I cannot get the syntax correct for passing them into the ‘gps’ data element as an array.

The code I have got is as follows:

  - alias: Device Tracker
      - platform: webhook
        webhook_id: device_tracker
      - service: device_tracker.see
          dev_id: 'phone'
          gps: ['{{ }} , {{trigger.json.lon }}']

Any ideas please?

You need a couple more quote characters:

          gps: ['{{ }}' , '{{trigger.json.lon }}']

Thanks for that. I thought I had tried every combination of quota characters.