Display a route from uploaded GPX on Google map widget

Hi all,

Has anyone done this and willing to share advice?

I'm trying to create this flow:

1. User creates an event (eg bike ride) as a document in an Events Collection

2. User uploads a gpx file of the planned route (this is a standard route planning tool)

3. Custom action extracts the Lat Lng coordinates of this route from the gpx and returns this as a list in the event document

4. Google maps widget displays this route as a polyline

I can do 1,2 and 4, but am getting stuck on 3 - I've generated custom code using the gpx package on pub Dev, but keep getting compile errors.

I was hoping for some tips if possible!