Parameter is null instead of an id with ModalRoute.of() - firebase

Question

I am developing a mobile App with Flutter and Firebase.
I am trying to use pushNamed() and hand over a parameter. (an id)
I don't know how i could solve my problem.
Here is my Code:
#override
void didChangeDependencies() {
if (_isInit) {
print(ModalRoute.of(context).settings.arguments);
final productId = ModalRoute.of(context).settings.arguments;
if (productId != null) {
_editedAngebot = Provider.of<Angebote>(context).findByID(productId);
_initValues = {
'titel': _editedAngebot.titel,
'beschreibung': _editedAngebot.beschreibung,
'semester': _editedAngebot.semester.toString(),
'fach': _editedAngebot.fach,
'abteilung': _editedAngebot.abteilung,
};
}
}
_isInit = false;
super.didChangeDependencies();
}
And the other class, where I set the parameter. My "Angebot" object only has a default constructor.
trailing: isAllowed()
? IconButton(
icon: Icon(Icons.edit),
onPressed: () {
Navigator.of(context).maybePop();
Navigator.of(context)
.pushNamed('/editAngebot', arguments: id);
})
Why is my ID null?

Answer 1

Your Id is null because you are popping a page first then pushing new page .
Use pushReplacementNamed()
Here is a code sample
import 'package:flutter/material.dart';
final Color darkBlue = Color.fromARGB(255, 18, 32, 47);
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
home: FirstPage(),
routes:{
Secondpage.routeName:(context)=>Secondpage(),
}
);
}
}
class FirstPage extends StatelessWidget {
final String id = '01';
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(child:ElevatedButton(
child: Text('GoTo secondPage'),
onPressed: (){
Navigator.of(context).pushReplacementNamed(Secondpage.routeName,arguments: id);
},
))
);
}
}
class Secondpage extends StatelessWidget {
static const routeName = 'secondpage';
#override
Widget build(BuildContext context) {
final data = ModalRoute.of(context).settings.arguments as String;
return Scaffold(
body: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Center(child:Text('$data')),
ElevatedButton(
child: Text('GoTo FirstPage'),
onPressed: (){
Navigator.of(context).pop();
},
)
],
)
);
}
}

Answer 2

you should probably change the id defined in the class to a dynamic type and it would work.. tested this and it works as fine
class Product with ChangeNotifier {
//changed to dynamic as errors with null and string came topping up
final dynamic id;
final String title;
final String description;
Product(
{required this.id,
required this.title,
required this.description,
});