how to pass data from login page to another url in flutter?

i want to pass login data (ID) from login page to another url (not other class in the same project) in flutter

example : i want to open "https://ift.tt/2ZQxxBH url) but i also want to pass ID from "https://ift.tt/2Zc0yJ3 url)

i tried to use :

final _dataID = {"loginid" : "$id"};
final url = Uri.encodeFull('http://mylink.com/test/$_dataID');
html.open.window(url,"test");

but it's not working, how to achieve that? thanks