Display a widget if the user is an admin flutter - flutter

Question

I have a "settings" screen where the user can click on "Admin mode" and then is asked for a password. If this password corresponds to a defined password that I'll give to the admins of the app, he has the app displaying all the admin widgets on the other screens.
I want to set a default admin password, when the user click on the "validate" button, the program check is the password is correct. I have a button on a screen that is like the "admin panel" and I want this button to be displayed only if the user is an admin.
Here is the Dialog I created and where I suppose I'll have to create something to check if the password is correct in the onPressed function.
class DialogModeAdmin extends StatelessWidget {
final GlobalKey<FormBuilderState> _fbKey = GlobalKey<FormBuilderState>();
String _passAdmin;
dialogContent(BuildContext context) {
return Container(
decoration: new BoxDecoration(
color: Colors.white,
shape: BoxShape.rectangle,
borderRadius: BorderRadius.circular(10),
boxShadow: [
BoxShadow(
color: Colors.black26,
blurRadius: 10.0,
offset: const Offset(0.0, 10.0),
),
],
),
child: SizedBox(
height: 120,
child: Column(
children: [
Padding(
padding: const EdgeInsets.only(top: 8.0),
child: Text("Mot de passe"),
),
Padding(
padding: const EdgeInsets.all(8.0),
child: Container(
decoration: new BoxDecoration(
color: Colors.white,
border: Border.all(
color: Colors.black,
width: 1,
),
boxShadow: [BoxShadow(
color: Color.fromRGBO(10, 10, 10, 0.25),
blurRadius: 5.0,
spreadRadius: -2.0,
offset: Offset(3.0, 5.0),
)],
borderRadius: BorderRadius.all(Radius.circular(5.0)),
),
child: SizedBox(
height: 30,
child: Padding(
padding: const EdgeInsets.only(left: 5.0, right: 5.0, top: 1.0, bottom: 4.0),
child: FormBuilderTextField(
// validator: FormBuilderValidators.required(context),
decoration: InputDecoration(
border: InputBorder.none,
),
name: 'passadmin',
onChanged: (String value) {
_passAdmin = value;
},
),
)
)
),
),
Padding(
padding: const EdgeInsets.only(top: 8.0),
child: SizedBox(
height: 30,
width: 90,
child: ElevatedButton(
style: ElevatedButton.styleFrom(
primary: Color.fromRGBO(255, 64, 0, 1.0),
onPrimary: Colors.white,
shape: const RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(10.0))),
),
onPressed: () async{
if(_fbKey.currentState.validate()){
// check if the password is correct and then set a local variable to true to set the privileges of an admin
}
},
child: Text('Valider'),
),
),
),
],
)
)
);
}
#override
Widget build(BuildContext context) {
return Dialog(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(10),
),
elevation: 0.0,
backgroundColor: Colors.transparent,
child: dialogContent(context),
);
}
}

Answer 1

You can store a isAdmin boolean in a static way or with ChangeNotifier (similar to observable).
https://flutter.dev/docs/development/data-and-backend/state-mgmt/simple
https://api.flutter.dev/flutter/foundation/ChangeNotifier-class.html
Then use this value to show/hide your widgets with the Visibility Widget
https://api.flutter.dev/flutter/widgets/Visibility-class.html
Visibility(
visible: // isAdmin variable,
child: ...
),
EDIT : For your problem to check the password :
class DialogModeAdmin extends StatelessWidget {
final GlobalKey<FormBuilderState> _fbKey = GlobalKey<FormBuilderState>();
String _passAdmin;
// This is your password
final String _password = "MyPassword";
dialogContent(BuildContext context) {
...
name: 'passadmin',
// Here you store correctly what the user typed
onChanged: (String value) {
_passAdmin = value;
},
),
...
child: ElevatedButton(
...
onPressed: () async{
if(_fbKey.currentState.validate()){
// check if the password is correct and then set a local variable to true to set the privileges of an admin
// As the comment says :
if(_passAdmin == _password){
// set the static/valueNotifier to true
} else {
// display an error 'wrong password'
}
}
},
child: Text('Valider'),
),
...
}