Why does my code give an error of a Null Check Operator used on a null value - flutter

Question

Here is the code
I wanted to register a user and I used a FormKey and I got the error Null
check operator use don a null value
here is what the run terminal shows
E/flutter (30851): [ERROR:flutter/lib/ui/ui_dart_state.cc(198)] Unhandled Exception: Null check operator used on a null value
E/flutter (30851): #0 _RegisterScreenState.signUp (package:em_home/screens/signing/register_screen.dart:58:29)
class RegisterScreen extends StatefulWidget {
const RegisterScreen({Key? key}) : super(key: key);
#override
_RegisterScreenState createState() => _RegisterScreenState();
}
class _RegisterScreenState extends State<RegisterScreen> {
showSnackBar(String content, BuildContext context) {
ScaffoldMessenger.of(context)
.showSnackBar(SnackBar(content: Text(content)));
}
bool _isLoading = false;
final formKey = GlobalKey<FormState>();
String email = "";
String password = "";
String fullName = "";
String dob = "";
String gender = "";
AuthMethods authMethods = AuthMethods();
Uint8List? image;
pickImage(ImageSource source) async {
final ImagePicker imagePicker = ImagePicker();
XFile? _file = await imagePicker.pickImage(source: source);
if (_file != null) {
return await _file.readAsBytes();
}
print("No Image selected");
}
void selectImage() async {
Uint8List im = await pickImage(ImageSource.gallery);
setState(() {
image = im;
});
}
signUp() async {
if (formKey.currentState!.validate()) {
setState(() {
_isLoading = true;
});
await authMethods.registerUser(email: email, password: password, name: fullName, gender: gender, dateOfBirth: dob,)
.then((value) async {
if (value == true) {
await HelperFunctions.saveUserLoggedInStatus(true);
await HelperFunctions.saveUserEmailSF(email);
await HelperFunctions.saveUserNameSF(fullName);
Navigator.pushReplacement(context, SlideLeftRoute(widget: const LoginScreen()));
} else {
showSnackBar(value, context);
setState(() {
_isLoading = false;
});
}
});
}
return null;
}
void navigatetoSignIn() {
Navigator.of(context)
.push(MaterialPageRoute(builder: (context) => const LoginScreen()));
}
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: backgroundColor,
body: SingleChildScrollView(
child: Container(
color: backgroundColor,
padding: const EdgeInsets.symmetric(horizontal: 15),
width: double.infinity,
child: Column(
children: [
const SizedBox(
height: 30,
),
Container(
alignment: Alignment.topLeft,
child: IconButton(
onPressed: () {
Navigator.pushReplacement(
context, SlideLeftRoute(widget: const LoginScreen()));
},
icon: const Icon(
Icons.arrow_back,
size: 40,
),
),
),
const SizedBox(
height: 20,
),
Image.asset(
'assets/logos.png',
),
const Text(
"Create your account",
style: TextStyle(color: textColor, fontWeight: FontWeight.bold),
),
const SizedBox(
height: 30,
),
Stack(
children: [
// to check if Image is not equal to null
image != null
? CircleAvatar(
radius: 64,
backgroundImage: MemoryImage(image!),
)
: const CircleAvatar(
radius: 64,
backgroundImage: AssetImage(
"assets/default_profile.jpg",
),
),
Positioned(
child: IconButton(
onPressed: selectImage,
icon: const Icon(Icons.add_a_photo),
),
left: 80,
bottom: -10,
)
],
),
const SizedBox(
height: 30,
),
TextFormField(
decoration: textInputDecoration.copyWith(
labelText: "Email",
prefixIcon: Icon(
Icons.email,
)),
onChanged: (val) {
setState(() {
email = val;
});
},
// check tha validation
validator: (val) {
return RegExp(
r"^[a-zA-Z0-9.a-zA-Z0-9.!#$%&'*+-/=?^_`{|}~]+#[a-zA-Z0-9]+\.[a-zA-Z]+")
.hasMatch(val!)
? null
: "Please enter a valid email";
},
),
const SizedBox(
height: 20,
),
TextFormField(
obscureText: true,
decoration: textInputDecoration.copyWith(
labelText: "Password",
prefixIcon: Icon(
Icons.lock,
color: backgroundColor,
)),
validator: (val) {
if (val!.length < 6) {
return "Password must be at least 6 characters";
} else {
return null;
}
},
onChanged: (val) {
setState(() {
password = val;
});
},
),
const SizedBox(
height: 20,
),
TextFormField(
decoration: textInputDecoration.copyWith(
labelText: "Full Name",
prefixIcon: Icon(
Icons.person,
)),
onChanged: (val) {
setState(() {
fullName = val;
});
},
validator: (val) {
if (val!.isNotEmpty) {
return null;
} else {
return "Name cannot be empty";
}
},
),
const SizedBox(
height: 20,
),
TextFormField(
decoration: textInputDecoration.copyWith(
labelText: "Date Of Birth DD/MM/YYYY",
prefixIcon: Icon(
Icons.lock,
)),
validator: (val) {},
onChanged: (val) {
setState(() {
dob = val;
});
},
),
const SizedBox(
height: 20,
),
TextFormField(
decoration: textInputDecoration.copyWith(
labelText: "Gender",
prefixIcon: Icon(
Icons.lock,
)),
validator: (val) {},
onChanged: (val) {
setState(() {
gender = val;
});
},
),
const SizedBox(
height: 20,
),
InkWell(
onTap: signUp,
child: Container(
width: double.infinity,
alignment: AlignmentDirectional.center,
padding: const EdgeInsets.symmetric(vertical: 12),
decoration: const ShapeDecoration(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.all(Radius.circular(4)),
),
color: buttonColor,
),
child: _isLoading
? const Center(
child: CircularProgressIndicator(
color: iconButtonColor,
),
)
: const Text(
"Sign up",
style: TextStyle(
color: buttonTextColor,
fontWeight: FontWeight.bold),
),
),
),
const SizedBox(
height: 50,
),
Container(
color: backgroundColor,
child: const Text("- or sign in using -"),
),
const SizedBox(
height: 25,
),
Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
GestureDetector(
onTap: () {
Navigator.push(context, CustomRoute(widget: const Scaffold(body: Center(child: Text("Coming Soon"),))));
},
child: Container(
width: 50,
height: 45,
color: Colors.white,
child: Image.asset('assets/google.png'),
),
),
const SizedBox(
width: 30,
),
GestureDetector(
onTap: () {
Navigator.push(context, CustomRoute(widget: const Scaffold(body: Center(child: Text("Coming Soon"),))));
},
child: Container(
width: 50,
height: 45,
color: Colors.white,
child: Image.asset('assets/facebook.png'),
),
),
],
),
],
),
),
),
);
}
}
please what do I do here is the snippet to the code

Answer 1

Wrap your UI with the FormFields inside a Form widget and pass the GlobalKey to it.
Quick guide from Flutter docs: https://docs.flutter.dev/cookbook/forms/validation