问题
I am using Firebase and keep getting this annoying message when I click on the Sign Up button :
flutter: 'package:firebase_auth_platform_interface/src/method_channel/method_channel_user_credential.dart': Failed assertion: line 14 pos 16: 'data != null': is not true.
The code works fine. The app is built and run successfully. This happens when I enter my phone, email and password and click on the signup button. My code is:
import 'package:flutter/material.dart';
import 'package:firebase_auth/firebase_auth.dart';
class Auth extends StatefulWidget {
@override
_AuthState createState() => _AuthState();
}
class _AuthState extends State<Auth> {
final _formKey = GlobalKey<FormState>();
final _password = TextEditingController(),
_email = TextEditingController(),
_phone = TextEditingController();
final _auth = FirebaseAuth.instance;
bool willLogin = true;
bool showPassword = false;
void _login() async {
_formKey.currentState.validate();
try {
final existingUser = await _auth.signInWithEmailAndPassword(
email: _email.text, password: _password.text);
if (existingUser != null) {
Navigator.pushNamed(context, '/home');
}
} catch (e) {
print(e);
}
}
void _signup() async {
_formKey.currentState.validate();
try {
final newUser = await _auth.createUserWithEmailAndPassword(
email: _email.text, password: _password.text);
if (newUser != null) {
Navigator.pushNamed(context, '/home');
}
} catch (e) {
print(e);
}
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Dog SOS"),
leading: Icon(Icons.pets),
),
body: Form(
key: _formKey,
child: ListView(
padding: const EdgeInsets.all(24),
children: [
const SizedBox(
height: 10,
),
Center(
child: CircleAvatar(
backgroundColor: Theme.of(context).primaryColor,
child: Icon(
Icons.shield,
color: Colors.white,
size: 50,
),
radius: 60,
),
),
const SizedBox(
height: 20,
),
if (!willLogin) ...[
TextFormField(
decoration: InputDecoration(
labelText: "Phone",
border: OutlineInputBorder(
borderRadius: BorderRadius.circular(8),
),
),
keyboardType: TextInputType.phone,
textInputAction: TextInputAction.next,
controller: _phone,
validator: (value) =>
value.isEmpty ? "Please Enter Phone Number" : null,
),
const SizedBox(
height: 10,
),
],
TextFormField(
decoration: InputDecoration(
labelText: "Email",
border: OutlineInputBorder(
borderRadius: BorderRadius.circular(8),
),
),
keyboardType: TextInputType.emailAddress,
textInputAction: TextInputAction.next,
controller: _email,
validator: (value) => value.isEmpty ? "Please Enter Email" : null,
),
const SizedBox(
height: 10,
),
TextFormField(
decoration: InputDecoration(
labelText: "Password",
border: OutlineInputBorder(
borderRadius: BorderRadius.circular(8),
),
suffixIcon: IconButton(
icon: Icon(
showPassword
? Icons.visibility_off_outlined
: Icons.visibility_outlined,
),
onPressed: () {
setState(() {
showPassword = !showPassword;
});
},
),
),
obscureText: !showPassword,
textInputAction: TextInputAction.done,
controller: _password,
validator: (value) =>
value.isEmpty ? "Please Enter Password" : null,
),
const SizedBox(
height: 10,
),
RaisedButton(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(8),
),
child: Text(
willLogin ? "\nLOGIN\n" : "\nSIGN UP\n",
style: Theme.of(context)
.textTheme
.button
.copyWith(color: Colors.white),
),
color: Theme.of(context).primaryColor,
onPressed: () {
if (_formKey.currentState.validate()) {
_formKey.currentState.save();
_login();
}
},
),
Row(
children: [
Text(willLogin
? "Don't have an account?"
: "Already have an account?"),
FlatButton(
child: Text(
willLogin ? "Create One." : "Login.",
style: Theme.of(context).textTheme.button.copyWith(
color: Theme.of(context).primaryColor,
),
),
onPressed: () {
setState(() {
willLogin = !willLogin;
if (_formKey.currentState.validate()) {
_formKey.currentState.save();
_signup();
}
});
},
),
],
),
],
),
),
);
}
}
回答1:
The problem is that here:
onPressed: () {
setState(() {
willLogin = !willLogin;
if (_formKey.currentState.validate()) {
_formKey.currentState.save();
_signup();
}
});
},
on click of this button, you are using setState and assign willLogin equal to false, therefore it is not even calling _signup() since it is immediately calling the build() method. So now you have willLogin = false, which is showing you this in the screen this widget:
child: Text(
willLogin ? "\nLOGIN\n" : "\nSIGN UP\n",
style: Theme.of(context)
.textTheme
.button
.copyWith(color: Colors.white),
),
color: Theme.of(context).primaryColor,
onPressed: () {
if (_formKey.currentState.validate()) {
_formKey.currentState.save();
_login();
}
},
),
Here according to your code if willLogin is false then show Sign up text and call _login() method. Since you are calling _login() method for sign up you are getting this error since the user is not even registered in firebase authentication.
What you need to do is change the logic, either remove setState, this way _signup() method will be called, or keep it as it is but change _login() to _signup().
Try the following:
child: Text(
willLogin ? "\nLOGIN\n" : "\nSIGN UP\n",
style: Theme.of(context)
.textTheme
.button
.copyWith(color: Colors.white),
),
color: Theme.of(context).primaryColor,
onPressed: () {
if (_formKey.currentState.validate()) {
_formKey.currentState.save();
willLogin ? _login() : _signup();
}
},
),
来源：https://stackoverflow.com/questions/65337850/flutter-assertion-error-flutter-packagefirebase-auth-platform-interface-src