An existing widget must be identified in the dashboard to be the target of the triggered action, of which the id <TARGET_WIDGET_NAME> must be noted. In this example the target is a WidgetSingleContent.
The JS function to be inserted in the appropriate CK Editor box (in more options) of the current widgetButton widget is of the following type:
function execute() {
$('body').trigger({
type: "showLastDataFromExternalContentGis_<TARGET_WIDGET_NAME>"
eventGenerator: $(this),
targetWidget: <TARGET_WIDGET_NAME>,
color1: "#acb2fa",
color2: "#231d5c",
widgetTitle: "Occupied Parking Lots (Alberti Car Park)",
field: "occupiedParkingLots",
serviceUri: "http://www.disit.org/km4city/resource/iot/orionUNIFI/DISIT/CarParkPal.Giustizia"
});
}