cannot navigate form login screen to bottom_tab_screen with provider - flutter

Question

I'm trying to navigate from login screen to the bottom tab screen but nothing happen and now i have no error
it is the main
return MultiProvider(
providers: [
ChangeNotifierProvider.value(value: UserProvider()),
ChangeNotifierProvider.value(value: AppProvider()),
],
child:MaterialApp(
key: key,
title: 'Voyager',
debugShowCheckedModeBanner: false,
theme: AppTheme.getTheme(),
routes: routes,
),
);
}
my dialog which has two cases if success or fail to login or sign up
import 'package:flutter/material.dart';
class Dialogs {
static showErrorDialog(BuildContext context,
{#required String message, #required int code}) {
showDialog(
context: context,
barrierDismissible: false,
builder: (BuildContext context) {
return AlertDialog(
actions: <Widget>[
FlatButton(
onPressed: () => Navigator.of(context).pop(),
child: Text('Ok'),
)
],
title: Text('error $code'),
content: Text(message),
backgroundColor: Colors.white,
);
},
);
}
}
my login method and it depend on user api provider
signIn() async {
var res = await userProvider.login(
_userNameController.text, _passwordController.text);
if (res is FailedRequest) {
Dialogs.showErrorDialog(widget._context , message: res.message, code: res.code);
print('results ${res.toString()}');
} else {
print("Signing in success");
Navigator.pushReplacement(
widget._context, MaterialPageRoute(builder: (context) => BottomTabScreen()));
}
userProvider.isLoading = false;
}
and the api provider which use in the login
Future<dynamic> login(String email, String password) async {
final Map<String, dynamic> body = {'email': email, 'password': password};
_isLoading = true;
notifyListeners();
print('Starting request');
http.Response response = await http.post(Environment.userLogin,
body: json.encode(body), headers: Environment.requestHeader);
print('Completed request');
print('user login response : ${response.body}');
Map<String, dynamic> res = json.decode(response.body);
var results;
if (res['code'] == 200) {
// login successful
_user = User.fromJson(res['message']);
results = true;
} else {
// login failed;
results =
FailedRequest(code: 400, message: res['error'], status: false);
}
_isLoading = false;
notifyListeners();
return results;
}
finally the failed request class if request not done
import 'package:flutter/foundation.dart';
class FailedRequest {
String message;
int code;
bool status;
FailedRequest({
#required this.message,
#required this.code,
#required this.status,
});
}

Answer 1

The Issue seems to be with the res['error'] can you verify that the field error actually exists and is not null.
At this block can you print the value of res['error']
else {
print(res['error']);
// login failed;
results =
FailedRequest(code: 400, message: res['error'], status: false);
}