'The named parameter 'email is required, but there's no corresponding argument
I've a problem with this kind of bug and I hope someone can please tell me how to fix it.
The code:
import 'package:flutter/material.dart';
import 'package:login_form/model/login_model.dart';
class LoginPage extends StatefulWidget {
const LoginPage({Key? key}) : super(key: key);
@override
_LoginPageState createState() => _LoginPageState();
}
class _LoginPageState extends State<LoginPage> {
final scaffoldKey = GlobalKey<ScaffoldState>();
GlobalKey<FormState> globalFormKey = new GlobalKey<FormState>();
bool hidePassword = true;
LoginRequestModel requestModel;
@override
void initState() {
super.initState();
requestModel = new LoginRequestModel();
}
@override
Widget build(BuildContext context) {
return Scaffold(
key: scaffoldKey,
backgroundColor: Theme.of(context).accentColor,
body: SingleChildScrollView(
child: Column(
children: <Widget>[
Stack(
children: <Widget>[
Container(
width: double.infinity,
padding: EdgeInsets.symmetric(vertical: 30, horizontal: 20),
margin: EdgeInsets.symmetric(vertical: 85, horizontal: 20),
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(20),
color: Theme.of(context).primaryColor,
boxShadow: [
BoxShadow(
color: Theme.of(context).hintColor.withOpacity(0.2),
offset: Offset(0, 10),
blurRadius: 20)
],
),
child: Form(
key: globalFormKey,
child: Column(
children: <Widget>[
SizedBox(
height: 25,
),
Text(
"Login",
style: Theme.of(context).textTheme.headline2,
),
SizedBox(
height: 20,
),
new TextFormField(
keyboardType: TextInputType.emailAddress,
onSaved: (input) => requestModel.email = input,
validator: (input) =>
!(input?.contains("@") ?? false)
? "Email id Should be valid"
: null,
decoration: new InputDecoration(
hintText: "Email Address",
enabledBorder: UnderlineInputBorder(
borderSide: BorderSide(
color: Theme.of(context)
.accentColor
.withOpacity(0.2),
)),
focusedBorder: UnderlineInputBorder(
borderSide: BorderSide(
color: Theme.of(context).accentColor)),
prefixIcon: Icon(Icons.email,
color: Theme.of(context).accentColor),
),
),
SizedBox(
height: 20,
),
new TextFormField(
keyboardType: TextInputType.text,
onSaved: (input) => requestModel.password = input,
validator: (input) => (input != null &&
input.length < 3)
? "Password should be more than < 3 characters"
: null,
obscureText: hidePassword,
decoration: new InputDecoration(
hintText: "Password",
enabledBorder: UnderlineInputBorder(
borderSide: BorderSide(
color: Theme.of(context)
.accentColor
.withOpacity(0.2),
)),
focusedBorder: UnderlineInputBorder(
borderSide: BorderSide(
color: Theme.of(context).accentColor)),
prefixIcon: Icon(Icons.lock,
color: Theme.of(context).accentColor),
suffixIcon: IconButton(
onPressed: () {
setState(() {
hidePassword = !hidePassword;
});
},
icon: Icon(hidePassword
? Icons.visibility_off
: Icons.visibility),
),
),
),
SizedBox(
height: 30,
),
TextButton(
child: Text(
"Login",
style: TextStyle(color: Colors.white),
),
onPressed: () {
if (validateAndSave()) {
print(requestModel.toJson());
}
},
style: TextButton.styleFrom(
padding: EdgeInsets.symmetric(
vertical: 12,
horizontal: 80,
),
backgroundColor:
Theme.of(context).accentColor,
shape: StadiumBorder())),
],
),
),
),
],
)
],
),
));
}
bool validateAndSave() {
final form = globalFormKey.currentState;
if (form!.validate()) {
form.save();
return true;
}
return false;
}
}
this is my Loginmodel.dart code
class LoginResponseModel {
final String status;
final String message;
final String kid;
final String uid;
final String email;
final String password;
LoginResponseModel({
required this.status,
required this.message,
required this.kid,
required this.uid,
required this.email,
required this.password});
factory LoginResponseModel.fromJson(Map<String, dynamic> json) {
return LoginResponseModel(
status: json["status"] as String? ?? "",
message: json["message"] as String? ?? "",
kid: json["kid"] as String? ?? "",
uid: json["uid"] as String? ?? "",
email: json["email"] as String? ?? "",
password: json["password"] as String? ?? "",
);
}
}
class LoginRequestModel {
String email;
String password;
LoginRequestModel({
required this.email,
required this.password,
});
Map<String, dynamic> toJson() {
Map<String, dynamic> map = {
'email': email.trim(),
'password': password.trim(),
};
return map;
}
}
The error:
The Error On LoginRequestModel requestModel; says " Non Nullable Instance field 'requestModel' must be initialized.
Then Error message on requestModel = new LoginRequestModel() says The Named Parameter 'email is required, but there's no corresponding argument.
And Last On OnSaved = input says "A value of type 'String?' can't be assigned to a variable of type 'string'."
I really appreciate the answer you gave
Solution 1:[1]
The Error On LoginRequestModel requestModel; says " Non Nullable Instance field 'requestModel' must be initialized.
You need to change:
LoginRequestModel requestModel;
Into the following since you are first setting the value in initState and therefore the variable are not going to be given a value right away then the object is created:
late LoginRequestModel requestModel;
Then Error message on requestModel = new LoginRequestModel() says The Named Parameter 'email is required, but there's no corresponding argument.
I don't know the content of the class LoginRequestModel but I would guess it has a named parameter email which is required to be specified when calling the LoginRequestModel constructor.
And Last On OnSaved = input says "A value of type 'String?' can't be assigned to a variable of type 'string'."
Again, I don't know your LoginRequestModel class but I would guess the email field is not nullable. That is a problem since onSave expects a method with the signature:
void FormFieldSetter<T>(
T? newValue
)
So your code here does not take into account that input is a nullable variable:
onSaved: (input) => requestModel.email = input
Since some of your problems is related to issues with Dart null-safety I will recommend you to read: https://dart.dev/null-safety
Solution 2:[2]
One by One,
The first one, you defined LoginRequestModel requestModel as non-nullable by default means that this variable is declared normally cannot be null. more detail You could just change LoginRequestModel requestModel; to LoginRequestModel requestModel= new LoginRequestModel();, instead of giving a value in initState. It looks like
LoginRequestModel requestModel = new LoginRequestModel();
@override
void initState() {
super.initState();
// requestModel = new LoginRequestModel();
}
Or use late (It is expensive)
Second one, I think in LoginRequestModel will lool like this LoginRequestModel({@required this.email}). You can choose to remove @required or give a empty value.
Last one, since requestModel.password and requestModel.email is non-nullable, it should like onSaved: (input) => requestModel.email = input!;
Solution 3:[3]
I think this should fix your problem. In order to solve the error
- assign the value of
requestModelat the time of declaring it instead of ininitState. - pass empty string as arguments to
LoginRequestModelbecauseemailandpasswordare required field. - write
input!instead ofinputto indicate thatinputis not null
import 'package:flutter/material.dart';
import 'package:login_form/model/login_model.dart';
class LoginPage extends StatefulWidget {
const LoginPage({Key? key}) : super(key: key);
@override
_LoginPageState createState() => _LoginPageState();
}
class _LoginPageState extends State<LoginPage> {
final scaffoldKey = GlobalKey<ScaffoldState>();
GlobalKey<FormState> globalFormKey = new GlobalKey<FormState>();
bool hidePassword = true;
LoginRequestModel requestModel = new LoginRequestModel('','');
@override
void initState() {
super.initState();
}
@override
Widget build(BuildContext context) {
return Scaffold(
key: scaffoldKey,
backgroundColor: Theme.of(context).accentColor,
body: SingleChildScrollView(
child: Column(
children: <Widget>[
Stack(
children: <Widget>[
Container(
width: double.infinity,
padding: EdgeInsets.symmetric(vertical: 30, horizontal: 20),
margin: EdgeInsets.symmetric(vertical: 85, horizontal: 20),
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(20),
color: Theme.of(context).primaryColor,
boxShadow: [
BoxShadow(
color: Theme.of(context).hintColor.withOpacity(0.2),
offset: Offset(0, 10),
blurRadius: 20)
],
),
child: Form(
key: globalFormKey,
child: Column(
children: <Widget>[
SizedBox(
height: 25,
),
Text(
"Login",
style: Theme.of(context).textTheme.headline2,
),
SizedBox(
height: 20,
),
new TextFormField(
keyboardType: TextInputType.emailAddress,
onSaved: (input) => requestModel.email = input!,
validator: (input) =>
!(input?.contains("@") ?? false)
? "Email id Should be valid"
: null,
decoration: new InputDecoration(
hintText: "Email Address",
enabledBorder: UnderlineInputBorder(
borderSide: BorderSide(
color: Theme.of(context)
.accentColor
.withOpacity(0.2),
)),
focusedBorder: UnderlineInputBorder(
borderSide: BorderSide(
color: Theme.of(context).accentColor)),
prefixIcon: Icon(Icons.email,
color: Theme.of(context).accentColor),
),
),
SizedBox(
height: 20,
),
new TextFormField(
keyboardType: TextInputType.text,
onSaved: (input) => requestModel.password = input!,
validator: (input) => (input != null &&
input.length < 3)
? "Password should be more than < 3 characters"
: null,
obscureText: hidePassword,
decoration: new InputDecoration(
hintText: "Password",
enabledBorder: UnderlineInputBorder(
borderSide: BorderSide(
color: Theme.of(context)
.accentColor
.withOpacity(0.2),
)),
focusedBorder: UnderlineInputBorder(
borderSide: BorderSide(
color: Theme.of(context).accentColor)),
prefixIcon: Icon(Icons.lock,
color: Theme.of(context).accentColor),
suffixIcon: IconButton(
onPressed: () {
setState(() {
hidePassword = !hidePassword;
});
},
icon: Icon(hidePassword
? Icons.visibility_off
: Icons.visibility),
),
),
),
SizedBox(
height: 30,
),
TextButton(
child: Text(
"Login",
style: TextStyle(color: Colors.white),
),
onPressed: () {
if (validateAndSave()) {
print(requestModel.toJson());
}
},
style: TextButton.styleFrom(
padding: EdgeInsets.symmetric(
vertical: 12,
horizontal: 80,
),
backgroundColor:
Theme.of(context).accentColor,
shape: StadiumBorder())),
],
),
),
),
],
)
],
),
));
}
bool validateAndSave() {
final form = globalFormKey.currentState;
if (form!.validate()) {
form.save();
return true;
}
return false;
}
}
Sources
This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.
Source: Stack Overflow
| Solution | Source |
|---|---|
| Solution 1 | julemand101 |
| Solution 2 | Sam Chan |
| Solution 3 | Abrar Malek |