I have a map in ArcGIS Online with a point layer showing lighting assets. These are symbolised based on unique type (post = circle, column = square).
The user will update a separate field to have a unique alphanumeric ID for each Asset.
I would like to use an Arcade expression to change the colour of the points when the field value changes from null to its new ID.
E.g. If the Unique ID is null the point colour is red, if the Unique ID is not null then colour green.
I haven't used the Arcade language before and cannot find guidance online for this particular query.