I got this error when I clicked my login button, I was expecting the validator would work but I just got this error every time I clicked my login button
════════ Exception caught by gesture ═══════════════════════════════════════════
The following _CastError was thrown while handling a gesture:
Null check operator used on a null value
When the exception was thrown, this was the stack
#0 _LoginPageState.build.<anonymous closure>
package:project_ukk/…/login/login_page.dart:153
#1 _InkResponseState._handleTap
package:flutter/…/material/ink_well.dart:989
#2 GestureRecognizer.invokeCallback
package:flutter/…/gestures/recognizer.dart:198
#3 TapGestureRecognizer.handleTapUp
package:flutter/…/gestures/tap.dart:608
#4 BaseTapGestureRecognizer._checkUp
package:flutter/…/gestures/tap.dart:296
#5 BaseTapGestureRecognizer.handlePrimaryPointer
package:flutter/…/gestures/tap.dart:230
#6 PrimaryPointerGestureRecognizer.handleEvent
package:flutter/…/gestures/recognizer.dart:563
#7 PointerRouter._dispatch
package:flutter/…/gestures/pointer_router.dart:94
#8 PointerRouter._dispatchEventToRoutes.<anonymous closure>
package:flutter/…/gestures/pointer_router.dart:139
#9 _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:539:8)
#10 PointerRouter._dispatchEventToRoutes
package:flutter/…/gestures/pointer_router.dart:137
#11 PointerRouter.route
package:flutter/…/gestures/pointer_router.dart:123
#12 GestureBinding.handleEvent
package:flutter/…/gestures/binding.dart:439
#13 GestureBinding.dispatchEvent
package:flutter/…/gestures/binding.dart:419
#14 RendererBinding.dispatchEvent
package:flutter/…/rendering/binding.dart:322
#15 GestureBinding._handlePointerEventImmediately
package:flutter/…/gestures/binding.dart:374
#16 GestureBinding.handlePointerEvent
package:flutter/…/gestures/binding.dart:338
#17 GestureBinding._flushPointerEventQueue
package:flutter/…/gestures/binding.dart:296
#18 GestureBinding._handlePointerDataPacket
package:flutter/…/gestures/binding.dart:279
#22 _invoke1 (dart:ui/hooks.dart:170:10)
#23 PlatformDispatcher._dispatchPointerDataPacket (dart:ui/platform_dispatcher.dart:331:7)
#24 _dispatchPointerDataPacket (dart:ui/hooks.dart:94:31)
(elided 3 frames from dart:async)
Handler: "onTap"
Recognizer: TapGestureRecognizer#db891
debugOwner: GestureDetector
state: possible
won arena
finalPosition: Offset(296.1, 619.7)
finalLocalPosition: Offset(266.1, 36.2)
button: 1
sent tap down
This is my login_page.dart
import 'package:flutter/material.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:project_ukk/constants/color_constant.dart';
import 'package:project_ukk/constants/font_and_padding.dart';
import 'package:project_ukk/pages/reset_password/reset_password.dart';
import 'package:project_ukk/pages/signUp/signup_page.dart';
import 'package:project_ukk/pages/user_page/navbar.dart';
import 'package:flutter_svg/svg.dart';
class LoginPage extends StatefulWidget {
const LoginPage({Key? key}) : super(key: key);
@override
State<LoginPage> createState() => _LoginPageState();
}
class _LoginPageState extends State<LoginPage> {
//Form Key
final _formKey = GlobalKey<FormState>();
var email = "";
var password = "";
final emailController = TextEditingController();
final passwordController = TextEditingController();
@override
void dispose() {
// Clean up the controller when the widget is disposed.
emailController.dispose();
passwordController.dispose();
super.dispose();
}
clearText() {
emailController.clear();
passwordController.clear();
}
userLogin() async {
try {
await FirebaseAuth.instance
.signInWithEmailAndPassword(email: email, password: password);
Navigator.pushReplacement(
context,
MaterialPageRoute(
builder: (context) => PageNavBar(),
),
);
} on FirebaseAuthException catch (e) {
if (e.code == 'user-not-found') {
print("No User Found for that Email");
ScaffoldMessenger.of(context).showSnackBar(
SnackBar(
backgroundColor: Colors.orangeAccent,
content: Text(
"No User Found for that Email",
style: TextStyle(fontSize: 18.0, color: Colors.black),
),
),
);
} else if (e.code == 'wrong-password') {
print("Wrong Password Provided by User");
ScaffoldMessenger.of(context).showSnackBar(
SnackBar(
backgroundColor: Colors.orangeAccent,
content: Text(
"Wrong Password Provided by User",
style: TextStyle(fontSize: 18.0, color: Colors.black),
),
),
);
}
}
}
@override
Widget build(BuildContext context) {
//Email Field
final emailField = TextFormField(
autofocus: false,
controller: emailController,
keyboardType: TextInputType.emailAddress,
validator: (value) {
if (value == null || value.isEmpty) {
return 'Please Enter Email';
} else if (!value.contains('@')) {
return 'Please Enter Valid Email';
}
return null;
},
textInputAction: TextInputAction.next,
decoration: InputDecoration(
prefixIcon: Icon(Icons.mail),
contentPadding: EdgeInsets.fromLTRB(20, 15, 20, 15),
hintText: "Email",
border: OutlineInputBorder(
borderRadius: BorderRadius.circular(10),
),
),
);
//Password Field
final passwordField = TextFormField(
autofocus: false,
controller: passwordController,
obscureText: true,
validator: (value) {
if (value == null || value.isEmpty) {
return 'Please Enter Password';
}
return null;
},
textInputAction: TextInputAction.next,
decoration: InputDecoration(
prefixIcon: Icon(Icons.vpn_key),
contentPadding: EdgeInsets.fromLTRB(20, 15, 20, 15),
hintText: "Password",
border: OutlineInputBorder(
borderRadius: BorderRadius.circular(10),
),
),
);
final loginButton = Material(
elevation: 2,
borderRadius: BorderRadius.circular(50),
child: Container(
width: MediaQuery.of(context).size.width,
height: 60,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(50),
gradient: LinearGradient(
colors: const [kDarkModerateCyan, kModerateCyan],
begin: Alignment.centerLeft,
end: Alignment.centerRight,
),
),
child: Material(
borderRadius: BorderRadius.circular(50),
color: Colors.transparent,
child: Center(
child: MaterialButton(
child: Text(
"Login",
textAlign: TextAlign.center,
style: textButton,
),
padding: EdgeInsets.fromLTRB(20, 10, 20, 15),
minWidth: MediaQuery.of(context).size.width,
onPressed: () {
// Validate returns true if the form is valid, otherwise false.
if (_formKey.currentState!.validate()) {
setState(() {
email = emailController.text;
password = passwordController.text;
});
userLogin();
}
},
),
),
),
),
);
final forgotPassword = Container(
padding: EdgeInsets.symmetric(
vertical: 10,
),
child: GestureDetector(
onTap: () => {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => ResetPassword(),
),
),
},
child: Text(
'Forgot Password ?',
style: TextStyle(
decoration: TextDecoration.underline,
color: Colors.grey,
),
),
),
);
final registerNow = Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
"Don't have an account? ",
style: TextStyle(color: Colors.grey),
),
GestureDetector(
child: Text(
"Register Now",
style: TextStyle(
color: kPrimaryColor,
fontWeight: FontWeight.bold,
fontSize: 15,
),
),
onTap: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => SignUpPage(),
),
);
},
),
],
);
return Scaffold(
backgroundColor: kWhiteColor,
body: Stack(
key: _formKey,
children: <Widget>[
SingleChildScrollView(
child: Column(
children: <Widget>[
Container(
width: MediaQuery.of(context).size.width,
height: 300,
decoration: BoxDecoration(
color: kWhiteColor,
borderRadius: BorderRadius.only(
bottomLeft: Radius.circular(100),
bottomRight: Radius.circular(100),
),
gradient: LinearGradient(
colors: [kDarkModerateCyan, kModerateCyan],
stops: [0.0, 1],
begin: Alignment.topCenter,
end: Alignment.bottomCenter,
),
),
child: Column(
mainAxisAlignment: MainAxisAlignment.start,
children: <Widget>[
SizedBox(
height: 60,
),
SizedBox(
width: 200,
height: 200,
child: SvgPicture.asset(
'assets/logo.svg',
fit: BoxFit.contain,
color: kWhiteColor,
),
),
],
),
),
Container(
padding: EdgeInsets.symmetric(
horizontal: 30,
),
width: MediaQuery.of(context).size.width,
child: Column(
crossAxisAlignment: CrossAxisAlignment.end,
children: <Widget>[
SizedBox(
height: 70,
),
emailField,
SizedBox(
height: 20,
),
passwordField,
SizedBox(
height: 20,
),
forgotPassword,
SizedBox(
height: 30,
),
loginButton,
SizedBox(
height: 50,
),
registerNow,
],
),
),
],
),
),
],
),
);
}
}
My code is not connected to Firebase yet because I want to test if my validator is working or not, but I got this error instead.
Thank you for reading my very long question.
CodePudding user response：
You have set the form key in Stack instead of a Form
To fix this, you can simply wrap your Stack with a Form, and move your key to that Form
like
...
return Scaffold(
body: Form(
key: _formKey,
child: Stack(
children: <Widget>[
...
Apart from that, I'd suggest putting your UI elements(login, email, and forgotPassword) outside the build method, to achieve it you'll have to create methods for them instead of having a field/variable