Incorrect use of ParentDataWidget when using TextField - flutter

Question

I get Incorrect use of ParentDataWidget every time I try to type in my TextField or when I move from the signup page to the login page by pressing "You already have an account?" button.
This is the code that I used for the UI
import 'package:flutter/material.dart';
import 'package:tariffo/HomePage.dart';
import 'auth.dart';
import 'LoginPage.dart';
import 'LoginScreen.dart';
import 'package:firebase_auth/firebase_auth.dart';
class SignupPage extends StatefulWidget {
#override
_SignupPageState createState() => _SignupPageState();
}
class _SignupPageState extends State<SignupPage> {
final _formKey = GlobalKey<FormState>();
String email = '';
String password = '';
String error = '';
bool loading = false;
final Authentication authentication = Authentication();
#override
Widget build(BuildContext context) {
Widget _backButton() {
return InkWell(
onTap: () {
Navigator.pop(context);
},
child: Container(
padding: EdgeInsets.symmetric(horizontal: 10),
child: Row(
children: <Widget>[
Container(
padding: EdgeInsets.only(left: 0, top: 10, bottom: 10),
child: Icon(Icons.keyboard_arrow_left, color: Colors.black),
),
Text('Back',
style: TextStyle(fontSize: 12, fontWeight: FontWeight.w500))
],
),
),
);
}
return loading
? Homepage()
: Scaffold(
resizeToAvoidBottomInset: false,
resizeToAvoidBottomPadding: false,
body: Container(
height: 900.0,
width: 500.0,
child: Column(
children: <Widget>[
Padding(
padding: const EdgeInsets.only(top: 50.0),
child: Row(
children: <Widget>[
IconButton(
icon: Icon(Icons.arrow_back_ios, color: Colors.white),
onPressed: () {
Navigator.pushReplacement(
context,
MaterialPageRoute(
builder: (context) => LoginScreen()));
},
)
],
),
),
Positioned(top: 40, left: 0, child: _backButton()),
Padding(
padding: const EdgeInsets.only(top: 40.0),
child: RichText(
text: TextSpan(
text: 'Tariffo',
style: TextStyle(
color: Colors.blue,
fontFamily: 'SignPainter',
fontSize: 60),
),
),
),
SizedBox(
height: 400.0,
child: Form(
key: _formKey,
child: Column(
children: <Widget>[
Padding(
padding: const EdgeInsets.only(
left: 80.0, right: 80.0, top: 40.0),
child: TextFormField(
validator: (val) =>
val.isEmpty ? 'enter email' : null,
onChanged: (val) {
setState(() => email = val);
},
style: TextStyle(color: Colors.black),
decoration: InputDecoration(
hintText: 'enter email',
hintStyle: TextStyle(
fontFamily: 'Antra',
fontSize: 12.0,
color: Colors.black)),
),
),
Padding(
padding: const EdgeInsets.only(
left: 80.0, right: 80.0, top: 40.0),
child: TextFormField(
validator: (val) => val.length < 8
? 'enter password > 8 digits'
: null,
onChanged: (val) {
setState(() => password = val);
},
style: TextStyle(color: Colors.black),
decoration: InputDecoration(
hintText: 'enter password',
hintStyle: TextStyle(
fontFamily: 'Antra',
fontSize: 12.0,
color: Colors.black)),
obscureText: true,
),
),
SizedBox(height: 50),
Padding(
padding: const EdgeInsets.only(top: 40.0),
child: MaterialButton(
color: Colors.blue,
onPressed: () async {
if (_formKey.currentState.validate()) {
setState(() => loading = true);
dynamic result = await authentication
.registerwithEmailAndPassword(
email, password);
if (result == null) {
setState(() => error =
'Sorry,These credentials will not work out');
loading = false;
}
}
},
child: Text(
'Sign up',
style: TextStyle(
fontFamily: 'Antra', color: Colors.white),
),
),
),
],
),
)),
_createAccountLabel(),
],
),
),
);
}
Widget _createAccountLabel() {
return InkWell(
onTap: () {
Navigator.push(
context, MaterialPageRoute(builder: (context) => LoginPage()));
},
child: Container(
margin: EdgeInsets.symmetric(vertical: 20),
padding: EdgeInsets.all(15),
alignment: Alignment.bottomCenter,
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'Do you have an account ?',
style: TextStyle(fontSize: 13, fontWeight: FontWeight.w600),
),
SizedBox(
width: 10,
),
Text(
'Login',
style: TextStyle(
color: Colors.blue,
fontSize: 13,
fontWeight: FontWeight.w600),
),
],
),
),
);
}
}
import 'package:flutter/material.dart';
import 'SignUp.dart';
import 'brazierContainer.dart';
import 'package:google_fonts/google_fonts.dart';
import 'LoginScreen.dart';
import 'HomePage.dart';
import 'auth.dart';
class LoginPage extends StatefulWidget {
LoginPage({Key key, this.title}) : super(key: key);
final String title;
#override
_LoginPageState createState() => _LoginPageState();
}
class _LoginPageState extends State<LoginPage> {
final _formKey = GlobalKey<FormState>();
String email = '';
String password = '';
String error = '';
bool loading = false;
final Authentication authentication = Authentication();
#override
Widget build(BuildContext context) {
Widget _backButton() {
return InkWell(
onTap: () {
Navigator.pop(context);
},
child: Container(
padding: EdgeInsets.symmetric(horizontal: 10),
child: Row(
children: <Widget>[
Container(
padding: EdgeInsets.only(left: 0, top: 10, bottom: 10),
child: Icon(Icons.keyboard_arrow_left, color: Colors.black),
),
Text('Back',
style: TextStyle(fontSize: 12, fontWeight: FontWeight.w500))
],
),
),
);
}
return loading
? Homepage()
: Scaffold(
resizeToAvoidBottomInset: false,
resizeToAvoidBottomPadding: false,
body: Container(
height: 900.0,
width: 500.0,
child: Column(
children: <Widget>[
Padding(
padding: const EdgeInsets.only(top: 50.0),
child: Row(
children: <Widget>[
IconButton(
icon: Icon(Icons.arrow_back_ios, color: Colors.white),
onPressed: () {
Navigator.pushReplacement(
context,
MaterialPageRoute(
builder: (context) => LoginScreen()));
},
)
],
),
),
Positioned(top: 40, left: 0, child: _backButton()),
Padding(
padding: const EdgeInsets.only(top: 40.0),
child: RichText(
text: TextSpan(
text: 'Tariffo',
style: TextStyle(
color: Colors.blue,
fontFamily: 'SignPainter',
fontSize: 60),
),
),
),
SizedBox(
height: 400.0,
child: Form(
key: _formKey,
child: Column(
children: <Widget>[
Padding(
padding: const EdgeInsets.only(
left: 80.0, right: 80.0, top: 40.0),
child: TextFormField(
validator: (val) =>
val.isEmpty ? 'enter email' : null,
onChanged: (val) {
setState(() => email = val);
},
style: TextStyle(color: Colors.black),
decoration: InputDecoration(
hintText: 'enter email',
hintStyle: TextStyle(
fontFamily: 'Antra',
fontSize: 12.0,
color: Colors.black)),
),
),
Padding(
padding: const EdgeInsets.only(
left: 80.0, right: 80.0, top: 40.0),
child: TextFormField(
validator: (val) => val.length < 8
? 'enter password > 8 digits'
: null,
onChanged: (val) {
setState(() => password = val);
},
style: TextStyle(color: Colors.black),
decoration: InputDecoration(
hintText: 'enter password',
hintStyle: TextStyle(
fontFamily: 'Antra',
fontSize: 12.0,
color: Colors.black)),
obscureText: true,
),
),
SizedBox(height: 50),
Padding(
padding: const EdgeInsets.only(top: 40.0),
child: MaterialButton(
color: Colors.blue,
onPressed: () async {
if (_formKey.currentState.validate()) {
setState(() => loading = true);
dynamic result = await authentication
.signUpWithEmailAndPassword(
email, password);
if (result == null) {
setState(() => error =
'Sorry,These credentials will not work out');
loading = false;
}
}
},
child: Text(
'Sign in',
style: TextStyle(
fontFamily: 'Antra', color: Colors.white),
),
),
),
Container(
padding: EdgeInsets.symmetric(vertical: 10),
alignment: Alignment.centerRight,
child: Text('Forgot Password ?',
style: TextStyle(
fontSize: 14,
fontWeight: FontWeight.w500)),
),
],
),
)),
_createAccountLabel(),
],
),
),
);
}
Widget _createAccountLabel() {
return InkWell(
onTap: () {
Navigator.push(
context, MaterialPageRoute(builder: (context) => SignupPage()));
},
child: Container(
margin: EdgeInsets.symmetric(vertical: 20),
padding: EdgeInsets.all(15),
alignment: Alignment.bottomCenter,
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'Don/t you have an account ?',
style: TextStyle(fontSize: 13, fontWeight: FontWeight.w600),
),
SizedBox(
width: 10,
),
Text(
'Register',
style: TextStyle(
color: Colors.blue,
fontSize: 13,
fontWeight: FontWeight.w600),
),
],
),
),
);
}
}
And this is the error:
════════ Exception caught by widgets library ═══════════════════════════════════
Incorrect use of ParentDataWidget.
════════════════════════════════════════════════════════════════════════════════
════════ Exception caught by widgets library ═══════════════════════════════════
The following assertion was thrown while applying parent data.:
Incorrect use of ParentDataWidget.
The ParentDataWidget Positioned(left: 0.0, top: 40.0) wants to apply ParentData of type StackParentData to a RenderObject, which has been set up to accept ParentData of incompatible type FlexParentData.
Usually, this means that the Positioned widget has the wrong ancestor RenderObjectWidget. Typically, Positioned widgets are placed directly inside Stack widgets.
The offending Positioned is currently placed inside a Column widget.

Answer 1

You are using Positioned in a Column. Positioned can only be used in a Stack. So consider replacing your Column with a Stack or use Alignment(x,y) to align it