Flutter : how to conditionally repeat a showDialog inside a ListView - flutter

Question

I am using the flutter_reactive_ble_example to connect to my Bluetooth module by modifying the file device_list.dart.
and I wonder how do I re prompt the user if password is wrong.
I'm fairly new to flutter, please do ask more details if required.
here is the code snippet that I currently have:
Flexible(
child: ListView(
children: widget.scannerState.discoveredDevices
.map(
(device) => ListTile(
title: Text(tile.name),
subtitle: Text("${tile.name}\n: ${tile.sub}"),
leading: const ConnectIcon(),
onTap: () async {
//stop the scan
widget.stopScan();
//connect to the device
await widget.deviceConn.connect(device.id);
//prompt user for password
final inputData = await showDialog(
context: context,
barrierDismissible:
false, // prevent user from closing the dialog by pressing outside the dialog
builder: (_) {
String userData = "";
return AlertDialog(
title: new Text("Enter Password"),
content: new TextField(
onChanged: (value) {
userData = value;
},
),
actions: <Widget>[
ElevatedButton(
child: Text('Ok'),
onPressed: () async {
//on press subscribe and send the password
response = await ble.subscribeToCharacteristic(characteristic);
//if data failure check, how do I reshow this showDialog??
response.listen((event) {
if(event == 1){
//if return 1, password correct
Navigator.of(context).pop(userData);
}else{
//if not reshow Dialog
//howw?
}
}
//send password
ble.writeCharacteristicWithoutResponse(characteristic, value: userData);
},
)
],
);
},
);
Navigator.of(context).pop(
inputData); // pass data back to the previous page
},
),
)
.toList(),
),
),

Answer 1

You can use a recursion I think, here an example
Future _showPasswordDialog(){
return showDialog(
context: context,
barrierDismissible:
false, // prevent user from closing the dialog by pressing outside the dialog
builder: (_) {
String userData = "";
return AlertDialog(
title: new Text("Enter Password"),
content: new TextField(
onChanged: (value) {
userData = value;
},
),
actions: <Widget>[
ElevatedButton(
child: Text('Ok'),
onPressed: () async {
//on press subscribe and send the password
response = await ble.subscribeToCharacteristic(characteristic);
//if data failure check, how do I reshow this showDialog??
response.listen((event) {
if(event == 1){
//if return 1, password correct
Navigator.of(context).pop(userData);
}else{
//if not reshow Dialog
//howw?
Navigator.of(context).pop();
_showPasswordDialog();
}
}
//send password
ble.writeCharacteristicWithoutResponse(characteristic, value: userData);
},
)
],
);
},
);
}

Answer 2

separate the the alert prompting as another function, and return user details if login success else return null.
Future<String> promptAlert(BuildContext context){
return showDialog(
context: context,
barrierDismissible:
false, // prevent user from closing the dialog by pressing outside the dialog
builder: (_) {
String userData = "";
return AlertDialog(
title: new Text("Enter Password"),
content: new TextField(
onChanged: (value) {
userData = value;
},
),
actions: <Widget>[
ElevatedButton(
child: Text('Ok'),
onPressed: () async {
//on press subscribe and send the password
response = await ble.subscribeToCharacteristic(characteristic);
//if data failure check, how do I reshow this showDialog??
response.listen((event) {
if(event == 1){
//if return 1, password correct
Navigator.of(context).pop(userData);
}else{
Navigator.of(context).pop();
}
}
//send password
ble.writeCharacteristicWithoutResponse(characteristic, value: userData);
},
)
],
);
},
);
}
and check for the returned value is not null on the ListItem onTap
bool isLogin = (await promptAlert(context)) !=null;
while(isLogin ){
ScaffoldMessenger.of(context).showSnackBar(SnackBar(
duration: Duration(seconds: 2),
content: Text('Login Failed Try again')));
String user= await Future.delayed(
Duration(seconds: 2), () => promptAlert(context));
isLogin = user !=null;
}
If you want to show a snackbar and delayed alert,
ScaffoldMessenger.of(context).showSnackBar(SnackBar(
duration: Duration(seconds: 2),
content: Text('Login Failed Try again'),
));
Future.delayed(
Duration(seconds: 2), () => promptAlert(context));