How to shift focus to next custom textfield in Flutter? - flutter

As per: How to shift focus to next textfield in flutter?, I used FocusScope.of(context).nextFocus() to shift focus. But this doesn't work when you use a reusable textfield class. It only works when you directly use TextField class inside Column.
import 'package:flutter/material.dart';
void main() {
return runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
final focus = FocusScope.of(context);
return MaterialApp(
title: 'Flutter Demo',
home: Scaffold(
body: SafeArea(
child: Column(
children: <Widget>[
CustomTextField(
textInputAction: TextInputAction.next,
onEditingComplete: () => focus.nextFocus(),
),
const SizedBox(height: 10),
CustomTextField(
textInputAction: TextInputAction.done,
onEditingComplete: () => focus.unfocus(),
),
],
),
),
),
);
}
}
class CustomTextField extends StatelessWidget {
final TextInputAction textInputAction;
final VoidCallback onEditingComplete;
const CustomTextField({
this.textInputAction = TextInputAction.done,
this.onEditingComplete = _onEditingComplete,
});
static _onEditingComplete() {}
#override
Widget build(BuildContext context) {
return TextField(
textInputAction: textInputAction,
onEditingComplete: onEditingComplete,
);
}
}
In this code, if I click next in keyboard it will not shift focus to next textfield. Please help me with this.

That's because the context doesn't have anything it could grab the focus from. Replace your code with this:
void main() => runApp(MaterialApp(home: MyApp()));
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
final focus = FocusScope.of(context);
return Scaffold(
appBar: AppBar(),
body: Column(
children: <Widget>[
CustomTextField(
textInputAction: TextInputAction.next,
onEditingComplete: () => focus.nextFocus(),
),
SizedBox(height: 10),
CustomTextField(
textInputAction: TextInputAction.done,
onEditingComplete: () => focus.unfocus(),
),
],
),
);
}
}

You need to wrap your fields in a form widget with a form key and use a TextFormField instead of textField widget. Set the action to TextInputAction.next and it should work! You can also use TextInput.done to trigger the validation.
Here a fully working exemple:
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
class LogInPage extends StatefulWidget {
LogInPage({Key key}) : super(key: key);
#override
_LogInPageState createState() => _LogInPageState();
}
class _LogInPageState extends State<LogInPage> {
final _formKey = new GlobalKey<FormState>();
bool isLoading = false;
String firstName;
String lastName;
String password;
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(),
backgroundColor: Colors.black,
body: body(),
);
}
Widget body() {
return Form(
key: _formKey,
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: [
showInput(
firstName,
TextInputType.name,
Icons.drive_file_rename_outline,
"FirstName",
TextInputAction.next,
onSaved: (value) => firstName = value.trim()),
showInput(lastName, TextInputType.name,
Icons.drive_file_rename_outline, "LastName", TextInputAction.next,
onSaved: (value) => lastName = value.trim()),
showInput(null, TextInputType.text, Icons.drive_file_rename_outline,
"Password", TextInputAction.done,
isPassword: true, onSaved: (value) => password = value),
Padding(
padding: EdgeInsets.symmetric(vertical: 10),
),
showSaveButton(),
],
),
);
}
Widget showInput(String initialValue, TextInputType textInputType,
IconData icon, String label, TextInputAction textInputAction,
{#required Function onSaved, bool isPassword = false}) {
return Padding(
padding: EdgeInsets.fromLTRB(16.0, 20.0, 16.0, 0.0),
child: new TextFormField(
style: TextStyle(color: Theme.of(context).primaryColorLight),
maxLines: 1,
initialValue: initialValue,
keyboardType: textInputType,
textInputAction: textInputAction,
autofocus: false,
obscureText: isPassword,
enableSuggestions: !isPassword,
autocorrect: !isPassword,
decoration: new InputDecoration(
fillColor: Theme.of(context).primaryColor,
hintText: label,
hintStyle: TextStyle(color: Theme.of(context).primaryColorDark),
filled: true,
contentPadding: new EdgeInsets.fromLTRB(10.0, 10.0, 10.0, 10.0),
border: new OutlineInputBorder(
borderRadius: new BorderRadius.circular(12.0),
),
icon: new Icon(
icon,
color: Theme.of(context).primaryColorLight,
)),
validator: (value) {
return value.isEmpty && !isPassword
? "You didn't filled this field."
: null;
},
onSaved: onSaved,
onFieldSubmitted:
textInputAction == TextInputAction.done ? (value) => save() : null,
),
);
}
Widget showSaveButton() {
return RaisedButton(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.all(Radius.circular(100))),
color: Theme.of(context).primaryColor,
padding: EdgeInsets.symmetric(vertical: 12, horizontal: 25),
child: isLoading
? SizedBox(height: 17, width: 17, child: CircularProgressIndicator())
: Text(
"Sauvegarder",
style: TextStyle(color: Theme.of(context).primaryColorLight),
),
onPressed: save,
);
}
void save() async {
if (_formKey.currentState.validate()) {
_formKey.currentState.save();
//TODO
}
}
}

FocusNode textSecondFocusNode = new FocusNode();
TextFormField textFirst = new TextFormField(
onFieldSubmitted: (String value) {
FocusScope.of(context).requestFocus(textSecondFocusNode);
},
);
TextFormField textSecond = new TextFormField(
focusNode: textSecondFocusNode,
);
// render textFirst and textSecond where you want

Related

How to validate the TextFormField as we type in the input in Flutter

I have created a login screen with textformfield for email id and password using flutter. Also, I have added the validation to check these fields. The code is as below;
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: HomePage(),
theme: ThemeData(
brightness: Brightness.dark,
),
);
}
}
class HomePage extends StatefulWidget {
#override
_HomePageState createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
var _formKey = GlobalKey<FormState>();
var isLoading = false;
void _submit() {
final isValid = _formKey.currentState.validate();
if (!isValid) {
return;
}
_formKey.currentState.save();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Form Validation"),
leading: Icon(Icons.filter_vintage),
),
//body
body: Padding(
padding: const EdgeInsets.all(16.0),
//form
child: Form(
key: _formKey,
child: Column(
children: <Widget>[
Text(
"Form-Validation In Flutter ",
style: TextStyle(fontSize: 24.0, fontWeight: FontWeight.bold),
),
//styling
SizedBox(
height: MediaQuery.of(context).size.width * 0.1,
),
TextFormField(
decoration: InputDecoration(labelText: 'E-Mail'),
keyboardType: TextInputType.emailAddress,
onFieldSubmitted: (value) {
//Validator
},
validator: (value) {
if (value.isEmpty ||
!RegExp(r"^[a-zA-Z0-9.a-zA-Z0-9.!#$%&'*+-/=?^_`{|}~]+#[a-zA-Z0-9]+\.[a-zA-Z]+")
.hasMatch(value)) {
return 'Enter a valid email!';
}
return null;
},
),
//box styling
SizedBox(
height: MediaQuery.of(context).size.width * 0.1,
),
//text input
TextFormField(
decoration: InputDecoration(labelText: 'Password'),
keyboardType: TextInputType.emailAddress,
onFieldSubmitted: (value) {},
obscureText: true,
validator: (value) {
if (value.isEmpty) {
return 'Enter a valid password!';
}
return null;
},
),
SizedBox(
height: MediaQuery.of(context).size.width * 0.1,
),
RaisedButton(
padding: EdgeInsets.symmetric(
vertical: 10.0,
horizontal: 15.0,
),
child: Text(
"Submit",
style: TextStyle(
fontSize: 24.0,
),
),
onPressed: () => _submit(),
)
],
),
),
),
);
}
}
The issue I am facing is, I want to validate the fields as soon as the user starts typing the input(dynamically) rather than clicking on the submit button to wait for the validation to happen. I did a lot of research yet could not find a solution. Thanks in advance for any help!
Flutter Form Validation with TextFormField
Here's an alternative implementation of the _TextSubmitWidgetState that uses a Form:
class _TextSubmitWidgetState extends State<TextSubmitForm> {
// declare a GlobalKey
final _formKey = GlobalKey<FormState>();
// declare a variable to keep track of the input text
String _name = '';
void _submit() {
// validate all the form fields
if (_formKey.currentState!.validate()) {
// on success, notify the parent widget
widget.onSubmit(_name);
}
}
#override
Widget build(BuildContext context) {
// build a Form widget using the _formKey created above.
return Form(
key: _formKey,
child: Column(
mainAxisSize: MainAxisSize.min,
crossAxisAlignment: CrossAxisAlignment.stretch,
children: [
TextFormField(
decoration: const InputDecoration(
labelText: 'Enter your name',
),
// use the validator to return an error string (or null) based on the input text
validator: (text) {
if (text == null || text.isEmpty) {
return 'Can\'t be empty';
}
if (text.length < 4) {
return 'Too short';
}
return null;
},
// update the state variable when the text changes
onChanged: (text) => setState(() => _name = text),
),
ElevatedButton(
// only enable the button if the text is not empty
onPressed: _name.isNotEmpty ? _submit : null,
child: Text(
'Submit',
style: Theme.of(context).textTheme.headline6,
),
),
],
),
);
}
}
source : https://codewithandrea.com/articles/flutter-text-field-form-validation/
May be this can help someone. Inside the TextFormField use this line of code:
autovalidateMode: AutovalidateMode.onUserInteraction
use autovalidateMode in your Form widget
Form(
key: _formKey,
autovalidateMode: AutovalidateMode.onUserInteraction,
child: FormUI(),
),

adding form with globalKey inside PageView.Builder

I have form and TextFromFilde inside PageView.builder, everytime chinge page it show me this error Duplicate GlobalKey detected in widget tree.
and some time that TextFormFilde is hideing.
all problome is GlobalKey, if I delete it every thing is working perfict but text filde is unfocused in every page I had to tap agin on it to type data
import 'package:flutter/material.dart';
void main() => runApp(Myapp());
class Myapp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: PageViewTest(),
);
}
}
class PageViewTest extends StatefulWidget {
#override
State<PageViewTest> createState() => _PageViewTestState();
}
List<TextEditingController> tecList;
var _formKey;
List controller = [
TextEditingController(),
TextEditingController(),
TextEditingController(),
];
List<String> _signing_hint_text = [
'type your domain',
'type your email',
'type your password',
];
List<String> _signing_input_label = [
'Domain',
'Email',
'Password',
];
Size mDeviceSize(BuildContext context) {
return MediaQuery.of(context).size;
}
PageController _pageController = PageController(initialPage: 0);
class _PageViewTestState extends State<PageViewTest> {
#override
void initState() {
// TODO: implement initState
_formKey = GlobalKey<FormState>();
// _pageController = PageController();
tecList = List.generate(3, (index) {
return TextEditingController();
});
super.initState();
}
#override
void dispose() {
// TODO: implement dispose
super.dispose();
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: Container(
margin: EdgeInsets.all(30),
child: PageView.builder(
controller: _pageController,
itemCount: 3,
itemBuilder: (context, index) {
return Column(
children: [
Form(
autovalidateMode: AutovalidateMode.onUserInteraction,
key: _formKey,
child: TextFormField(
autofocus: true,
textAlign: TextAlign.right,
textInputAction: TextInputAction.next,
style: TextStyle(color: Color(0xff030303)),
cursorColor: Color(0xff5e6593),
controller: tecList[index],
keyboardType: TextInputType.text,
decoration: InputDecoration(
hintText: _signing_hint_text[index],
focusedBorder: OutlineInputBorder(
borderSide: BorderSide(
color: Color(0xff5e6593),
),
),
contentPadding:
EdgeInsets.symmetric(vertical: 5.0, horizontal: 10),
labelText: _signing_input_label[index],
labelStyle: TextStyle(color: Color(0xff5e6593)),
floatingLabelBehavior: FloatingLabelBehavior.auto,
border: OutlineInputBorder(),
alignLabelWithHint: true,
hintStyle: TextStyle(
color: Color(0xff5e6593),
fontSize: 15,
fontWeight: FontWeight.normal),
),
),
),
ElevatedButton(
onPressed: () {
_pageController.nextPage(
duration: Duration(milliseconds: 800),
curve: Curves.ease);
},
child: Text('click')),
],
);
}),
),
),
);
}
}
You can not use one formKey for all Form widgets in each page, you should define formKey for each page of your page view and use index to know which one is for which page. For example define three different formKey and use index like this:
List<GlobalKey<FormState>> formKeys = [GlobalKey<FormState>(),GlobalKey<FormState>(),GlobalKey<FormState>()];
and inside your PageView.builder, do this:
Form(
autovalidateMode: AutovalidateMode.onUserInteraction,
key: formKeys[index],
...
)
But For focus each TextFormField when page change, first define a list like this:
List<FocusNode> focusList = [FocusNode(), FocusNode(), FocusNode()];
then do this inside PageView.builder:
PageView.builder(
onPageChanged: (value) {
FocusScope.of(context).requestFocus(focusList[value]);
},
controller: _pageController,
itemCount: 3,
...
}
And also do not forget to pass those focusNode to TextFormField:
child: TextFormField(
focusNode: focusList[index],
autofocus: true,
textAlign: TextAlign.right,
...
)

Hello, Im new to flutter and still practicing basics. I wanted to learn how to set default credentials on login page without using firebase auth

class LoginPage extends StatelessWidget {
final _username = "admin";
final _password = "123";
final usernameController = TextEditingController();
final passwordController = TextEditingController();
#override
Widget build(BuildContext context) {
return Scaffold(body: Container(
child: Column(children: [
Padding(
padding: EdgeInsets.all(20.0),
child: TextField(
controller: usernameController,
decoration: InputDecoration(
border: OutlineInputBorder(),
labelText: "Username"),
autofocus: true;)),
Padding(
padding: EdgeInsets.all(20.0),
child: TextField(
controller: passwordController,
decoration: InputDecoration(
border: OutlineInputBorder(),
labelText: "Password"),
obscureText: true;)),
how do i compare the values inputted and the default credentials before proceeding to HomePage?
ElevatedButton(
onPressed: (){Navigator.push(context,
MaterialPageRoute(builder: (context) => HomePage()));})
])
)
);
}
What I wanted to happen is once the user entered the correct default credentials (ex. Uname=admin, pass=123) the login button will proceed to my HomePage(). Else it will give me a message to try it again. Again, I dont want to use firebase authentication just yet. If there's a way I could do this,
import 'package:flutter/material.dart';
import 'homepage.dart';
#override
class LoginPageState extends StatefulWidget {
static const String id = 'Home';
LoginPage createState() => LoginPage();}
class LoginPage extends State<LoginPageState>{
final _formKey = GlobalKey<FormState>();
final _username = "admin";
final _password = "123";
final usernameController = TextEditingController();
final passwordController = TextEditingController();
#override
void dispose() {
usernameController.dispose();
passwordController.dispose();
super.dispose();
}
void _submit() {
if(_formKey.currentState.validate()){
if(_username == usernameController.text && _password == passwordController.text) {
Navigator.push(
context, MaterialPageRoute(builder: (context) => HomePage()));
} else {
// whatever you want to do
// you can show a dialog box
}
}
}
#override
Widget build(BuildContext context) {
return Form(
key: _formKey,
child: Column(children: [
//USERNAME
Padding(
padding: EdgeInsets.fromLTRB(20.0, 90.0, 20.0, 20.0),
child:TextFormField(
autofocus: true,
controller: usernameController,
decoration: InputDecoration(
border: OutlineInputBorder(),
labelText: "Username"),
validator: (value){
if (value.isEmpty){
return "Username required";}
return null;
},
),
),
//PASSWORD
Padding(
padding: EdgeInsets.all(20.0),
child: TextFormField(
obscureText: true,
controller: passwordController,
decoration: InputDecoration(
border: OutlineInputBorder(),
labelText: "Password"),
validator: (value){
if (value.isEmpty){
return "Password required";}
return null;
})),
//LOGIN
ElevatedButton(
style: ButtonStyle(
backgroundColor: MaterialStateProperty.all<Color>(Colors.green[300])),
child: Text("LOGIN",
style: TextStyle(color: Colors.black)),
onPressed: _submit,
)
]
)
);
}
}
it is a good practise to dispose TextEditingController when it is no longer needed. Check https://api.flutter.dev/flutter/widgets/TextEditingController-class.html for more info.
I think this should solve your problem.
Simply create two variable username="admin" and password="123".
Get the input from the user and compare with username and password.
If both match simply redirect to the Homepage
Else assign a bool variable like invalid true (Don't forget to use setState((){}))
And just above/below the login button create a
if(invalid == true)
Text("Try Again")
Anyhow, I finally got this. Thanks to #adrsh23 for the answer! So here's how I did it:
First I have the scaffolded login page. This does not contain my login form just yet
import 'package:flutter/material.dart';
import 'LoginPageState.dart';
class LoginPage extends StatelessWidget{
Widget build(BuildContext context){
return Scaffold(
body: Container(
child: SingleChildScrollView(
child: Column(
children: [
Padding(
padding: EdgeInsets.fromLTRB(20.0, 90.0, 20.0, 20.0),
child: Container(
color: Colors.green[300],
padding: EdgeInsets.symmetric(horizontal: 50.0, vertical: 20.0),
child: Text("Sample Flutter Login"))),
LoginPageState(),]
)
)
)
);
}
}
And here, I created a stateful widget that already contains my form:
import 'package:flutter/material.dart';
import 'homepage.dart';
#override
class LoginPageState extends StatefulWidget {
LoginPage createState() => LoginPage();}
class LoginPage extends State<LoginPageState>{
final _formKey = GlobalKey<FormState>();
final _username = "admin";
final _password = "123";
final usernameController = TextEditingController();
final passwordController = TextEditingController();
#override
Widget build(BuildContext context) {
return Form(
key: _formKey,
child: Column(children: [
//USERNAME
Padding(
padding: EdgeInsets.fromLTRB(20.0, 90.0, 20.0, 20.0),
child:TextFormField(
autofocus: true,
controller: usernameController,
decoration: InputDecoration(
border: OutlineInputBorder(),
labelText: "Username"),
validator: (value){
if (value.isEmpty || value != _username){
return "Input correct username";}
return null;
})),
//PASSWORD
Padding(
padding: EdgeInsets.all(20.0),
child: TextFormField(
obscureText: true,
controller: passwordController,
decoration: InputDecoration(
border: OutlineInputBorder(),
labelText: "Password"),
validator: (value){
if (value.isEmpty || value != _password){
return "Input correct password";}
return null;
})),
//LOGIN
ElevatedButton(
style: ButtonStyle(
backgroundColor: MaterialStateProperty.all<Color>(Colors.green[300])),
child: Text("LOGIN",
style: TextStyle(color: Colors.black)),
onPressed: ( ) {
if(_formKey.currentState.validate()){
Navigator.push(
context, MaterialPageRoute(builder: (context) => HomePage()));
}
},
)
]
)
);
}
}
I used this for a basic flutter login that does not have firebase auth, instead using a default credentials.

How to validate form if at least n TextFormField are filled and retrieve their value in Flutter?

I have three different TextFormFields inside a Form, but only two of them can be filled at the same time.What I would like to achieve, is that whenerver two of them are filled, the other one should not be enabled.
They should be aware of changes in other fields at any time.
Below them is a RaisedButton that should be enabled when this condition is met.
Moreover, I need to do some logic with their values when the said button is pressed.
This is what I have right now:
class LPFilterCalculator extends StatefulWidget {
#override
State<StatefulWidget> createState() => _LPFilterCalculatorState();
}
class _LPFilterCalculatorState extends State<LPFilterCalculator> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: PersistentAppBar("Low Pass Filter").build(context),
drawer: DrawerMenu(),
body: Column(
children: <Widget>[
LowPassInputForm(),
],
),
);
}
}
/// Inputform class for Calculators
class LowPassInputForm extends StatefulWidget {
#override
State<StatefulWidget> createState() => _LowPassInputFormState();
}
class _LowPassInputFormState extends State<LowPassInputForm> {
ValueNotifier<bool> pressed = ValueNotifier(false);
final _formKey = GlobalKey<FormState>();
final resistanceTextController = TextEditingController();
final capacitorTextController = TextEditingController();
final frequencyTextController = TextEditingController();
#override
Widget build(BuildContext context) {
print('state update');
return Form(
onChanged: () => {},
key: _formKey,
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
children: <Widget>[
Column(
children: <Widget>[
TextFormField(
controller: resistanceTextController,
inputFormatters: <TextInputFormatter>[
WhitelistingTextInputFormatter.digitsOnly
],
keyboardType: TextInputType.number,
decoration:
const InputDecoration(hintText: 'Enter resistance value'),
),
TextFormField(
controller: capacitorTextController,
inputFormatters: <TextInputFormatter>[
WhitelistingTextInputFormatter.digitsOnly
],
keyboardType: TextInputType.number,
decoration:
const InputDecoration(hintText: 'Enter capacitor value'),
),
TextFormField(
controller: frequencyTextController,
inputFormatters: <TextInputFormatter>[
WhitelistingTextInputFormatter.digitsOnly
],
keyboardType: TextInputType.number,
decoration: const InputDecoration(
hintText: 'Enter desired cutoff frequency'),
),
RaisedButton(
elevation: 5.0,
onPressed: () {
calculateLowPass();
},
),
],
),
],
),
),
);
}
void calculateLowPass() {
var resistance = resistanceTextController.text;
var capacitor = capacitorTextController.text;
var frequency = frequencyTextController.text;
// do calculations
}
#override
void dispose() {
frequencyTextController.dispose();
super.dispose();
}
}
You should note I'm not really using some properties as well as functionalities of objects, as I'm not really sure which is the correct or best way to approach this in Flutter.
Any tips would be more than welcomed!
i am sure there are better way of doing it, but here is how i did it, i used the enabled property on TextFormField and created a method for each one that take the controller of the other two TextFormField, i also created one for the button to check the all the text form fields, here is the full code:
/// Inputform class for Calculators
class LowPassInputForm extends StatefulWidget {
#override
State<StatefulWidget> createState() => _LowPassInputFormState();
}
class _LowPassInputFormState extends State<LowPassInputForm> {
ValueNotifier<bool> pressed = ValueNotifier(false);
final _formKey = GlobalKey<FormState>();
bool isEnabled = true;
final resistanceTextController = TextEditingController();
final capacitorTextController = TextEditingController();
final frequencyTextController = TextEditingController();
bool checkResistanceController() =>
frequencyTextController.text.isEmpty ||
capacitorTextController.text.isEmpty;
bool checkCapacitorController() =>
frequencyTextController.text.isEmpty ||
resistanceTextController.text.isEmpty;
bool checkFrequencyController() =>
resistanceTextController.text.isEmpty ||
capacitorTextController.text.isEmpty;
bool enableButton() =>
!checkFrequencyController() ||
!checkCapacitorController() ||
!checkResistanceController();
#override
Widget build(BuildContext context) {
print('state update');
return Form(
onChanged: () => setState(() {
checkResistanceController();
}),
key: _formKey,
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
children: <Widget>[
Column(
children: <Widget>[
TextFormField(
enabled: checkResistanceController(),
controller: resistanceTextController,
inputFormatters: <TextInputFormatter>[
WhitelistingTextInputFormatter.digitsOnly
],
keyboardType: TextInputType.number,
decoration:
const InputDecoration(hintText: 'Enter resistance value'),
),
TextFormField(
enabled: checkCapacitorController(),
controller: capacitorTextController,
inputFormatters: <TextInputFormatter>[
WhitelistingTextInputFormatter.digitsOnly
],
keyboardType: TextInputType.number,
decoration:
const InputDecoration(hintText: 'Enter capacitor value'),
),
TextFormField(
enabled: checkFrequencyController(),
controller: frequencyTextController,
inputFormatters: <TextInputFormatter>[
WhitelistingTextInputFormatter.digitsOnly
],
keyboardType: TextInputType.number,
decoration: const InputDecoration(
hintText: 'Enter desired cutoff frequency'),
),
RaisedButton(
elevation: 5.0,
onPressed:
enableButton() ? () => calculateLowPass() : null),
],
),
],
),
),
);
}
void calculateLowPass() {
var resistance = resistanceTextController.text;
var capacitor = capacitorTextController.text;
var frequency = frequencyTextController.text;
// do calculations
}
#override
void dispose() {
frequencyTextController.dispose();
super.dispose();
}
}
You need to use the enabled property on the TextFormField and check whether the other two fields are empty. If any of the fields is empty then you enable the current field.
You could save your data in an Object model:
class Object {
// for the sake of this example the fields here are strings, but in practice it's better to change them to double
String resistance;
String capacitor;
String frequency;
Object({
this.resistance = '',
this.capacitor = '',
this.frequency = '',
});
}
Your updated state looks like this with the added Object instance:
class _LowPassInputFormState extends State<LowPassInputForm> {
final _formKey = GlobalKey<FormState>();
final resistanceTextController = TextEditingController();
final capacitorTextController = TextEditingController();
final frequencyTextController = TextEditingController();
Object data = Object();
#override
Widget build(BuildContext context) {
return Form(
onChanged: () => {},
key: _formKey,
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
children: <Widget>[
Column(
children: <Widget>[
TextFormField(
enabled: data.capacitor.isEmpty || data.frequency.isEmpty,
onChanged: (val) => setState(() => data.resistance = val),
controller: resistanceTextController,
inputFormatters: <TextInputFormatter>[
WhitelistingTextInputFormatter.digitsOnly
],
keyboardType: TextInputType.number,
decoration:
const InputDecoration(hintText: 'Enter resistance value'),
),
TextFormField(
enabled: data.resistance.isEmpty || data.frequency.isEmpty,
onChanged: (val) => setState(() => data.capacitor = val),
controller: capacitorTextController,
inputFormatters: <TextInputFormatter>[
WhitelistingTextInputFormatter.digitsOnly
],
keyboardType: TextInputType.number,
decoration:
const InputDecoration(hintText: 'Enter capacitor value'),
),
TextFormField(
enabled: data.resistance.isEmpty || data.capacitor.isEmpty,
onChanged: (val) => setState(() => data.frequency = val),
controller: frequencyTextController,
inputFormatters: <TextInputFormatter>[
WhitelistingTextInputFormatter.digitsOnly
],
keyboardType: TextInputType.number,
decoration: const InputDecoration(
hintText: 'Enter desired cutoff frequency'),
),
RaisedButton(
elevation: 5.0,
onPressed: () {
calculateLowPass();
},
),
],
),
],
),
),
);
}
void calculateLowPass() {
// use data to do calculations
}
}

Flutter provider, Right way to use GlobalKey<FormState> in Provider

I'm new at Provider package. and Just making demo app for learning purpose.
Here is my code of simple Form Widget.
1) RegistrationPage (Where my app is start)
class RegistrationPage extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
centerTitle: true,
title: Text("Title"),
),
body: MultiProvider(providers: [
ChangeNotifierProvider<UserProfileProvider>.value(value: UserProfileProvider()),
ChangeNotifierProvider<RegiFormProvider>.value(value: RegiFormProvider()),
], child: AllRegistrationWidgets()),
);
}
}
class AllRegistrationWidgets extends StatelessWidget {
#override
Widget build(BuildContext context) {
return GestureDetector(
onTap: () {
FocusScope.of(context).requestFocus(FocusNode());
},
child: Container(
child: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
Expanded(
child: SingleChildScrollView(
child: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
SetProfilePicWidget(),
RegistrationForm(),
],
),
),
),
BottomSaveButtonWidget()
],
),
),
);
}
}
class BottomSaveButtonWidget extends StatelessWidget {
#override
Widget build(BuildContext context) {
final _userPicProvider =
Provider.of<UserProfileProvider>(context, listen: false);
final _formProvider =
Provider.of<RegiFormProvider>(context, listen: false);
return SafeArea(
bottom: true,
child: Container(
margin: EdgeInsets.all(15),
child: FloatingActionButton.extended(
heroTag: 'saveform',
icon: null,
label: Text('SUBMIT',
style: TextStyle(
fontSize: 16,
fontWeight: FontWeight.bold,
)),
onPressed: () {
print(_userPicProvider.strImageFileName);
_formProvider.globalFormKey.currentState.validate();
print(_formProvider.firstName);
print(_formProvider.lastName);
},
)),
);
}
}
2) RegistrationForm
class RegistrationForm extends StatefulWidget {
#override
_RegistrationFormState createState() => _RegistrationFormState();
}
class _RegistrationFormState extends State<RegistrationForm> {
TextEditingController _editingControllerFname;
TextEditingController _editingControllerLname;
#override
void initState() {
_editingControllerFname = TextEditingController();
_editingControllerLname = TextEditingController();
super.initState();
}
#override
Widget build(BuildContext context) {
final formProvider = Provider.of<RegiFormProvider>(context);
return _setupOtherWidget(formProvider);
}
_setupOtherWidget(RegiFormProvider _formProvider) {
return Container(
padding: EdgeInsets.all(12),
child: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
SizedBox(height: 20),
Text(
'Fields with (*) are required.',
style: TextStyle(fontStyle: FontStyle.italic),
textAlign: TextAlign.left,
),
SizedBox(height: 20),
_formSetup(_formProvider)
],
),
);
}
_formSetup(RegiFormProvider _formProvider) {
return Form(
key: _formProvider.globalFormKey,
child: Container(
child: Column(
children: <Widget>[
TextFormField(
controller: _editingControllerFname,
textCapitalization: TextCapitalization.sentences,
decoration: InputDecoration(
labelText: "First Name *",
hintText: "First Name *",
),
onSaved: (value) {},
validator: (String value) =>
_formProvider.validateFirstName(value)),
SizedBox(height: 15),
TextFormField(
controller: _editingControllerLname,
textCapitalization: TextCapitalization.sentences,
validator: (String value) =>
_formProvider.validateLastName(value),
onSaved: (value) {},
decoration: InputDecoration(
labelText: "Last Name *",
hintText: "Last Name *",
),
)
],
),
),
);
}
#override
void dispose() {
_editingControllerFname.dispose();
_editingControllerLname.dispose();
super.dispose();
}
}
3) RegiFormProvider
class RegiFormProvider with ChangeNotifier {
final GlobalKey<FormState> globalFormKey = GlobalKey<FormState>();
String _strFirstName;
String _strLasttName;
String get firstName => _strFirstName;
String get lastName => _strLasttName;
String validateFirstName(String value) {
if (value.trim().length == 0)
return 'Please enter first name';
else {
_strFirstName = value;
return null;
}
}
String validateLastName(String value) {
if (value.trim().length == 0)
return 'Please enter last name';
else {
_strLasttName = value;
return null;
}
}
}
Here you can see, RegiFormProvider is my first page where other is children widgets in widget tree. I'm using final GlobalKey<FormState> globalFormKey = GlobalKey<FormState>(); in the RegiFormProvider provider, Because I want to access this in the 1st RegistrationPage to check my firstName and lastName is valid or not.
I'm using a builder widget to get form level context like below , and then easily we can get the form instance by using that context. by this way we don't need global key anymore.
Form(
child: Builder(
builder: (ctx) {
return ListView(
padding: EdgeInsets.all(12),
children: <Widget>[
TextFormField(
decoration: InputDecoration(labelText: "Title"),
textInputAction: TextInputAction.next,
onFieldSubmitted: (_) => FocusScope.of(context).nextFocus(),
initialValue: formProduct.title,
validator: validateTitle,
onSaved: (value) {
formProduct.title = value;
},
),
TextFormField(
decoration: InputDecoration(labelText: "Price"),
textInputAction: TextInputAction.next,
onFieldSubmitted: (_) => FocusScope.of(context).nextFocus(),
initialValue: formProduct.price == null
? ""
: formProduct.price.toString(),
keyboardType: TextInputType.number,
validator: validatePrice,
onSaved: (value) {
formProduct.price = double.parse(value);
},
),
TextFormField(
decoration: InputDecoration(labelText: "Description"),
textInputAction: TextInputAction.next,
initialValue: formProduct.description,
maxLines: 3,
validator: validateDescription,
onFieldSubmitted: (_) => FocusScope.of(context).nextFocus(),
onSaved: (value) {
formProduct.description = value;
},
),
TextFormField(
decoration: InputDecoration(labelText: "Image Url"),
textInputAction: TextInputAction.done,
onFieldSubmitted: (_) => FocusScope.of(context).unfocus(),
initialValue: formProduct.imageUrl,
validator: validateImageUrl,
onSaved: (value) {
formProduct.imageUrl = value;
},
),
Padding(
padding: EdgeInsets.all(10),
child: FlatButton(
color: Colors.amberAccent,
onPressed: () {
if (Form.of(ctx).validate()) {
Form.of(ctx).save();
formProduct.id =
Random.secure().nextDouble().toString();
ProductsProvider provider =
Provider.of<ProductsProvider>(context,
listen: false);
editing
? provider.setProduct(formProduct)
: provider.addProduct(formProduct);
Router.back(context);
}
},
child: Text("Save"),
),
)
],
);
},
),
)
you can see the Form.of(ctx) gives us the current level form.