Flutter - How to set focusNode from Parent to Child widget? - dart

Question

I have a Bottom Navigation in parent widget, and a few textfields in child widget. When user clicks on the navigation tab and if one of the textfields is empty, it will set focus on the particular textfields.
I am using the constructor method learnt from one of the developer however I couldn't get it work. It seems like I didn't pass over the context properly. I am not sure.
Anyone able to spot my mistakes or advise other methods which can achieve the same result?
login.dart
class Login extends StatefulWidget{
#override
State<StatefulWidget> createState() {
return _LoginState();
}
}
class _LoginState extends State<Login> {
FocusNode focusNode;
Page1 focus;
#override
void initState() {
super.initState();
focusNode = new FocusNode();
focus = new Page1(focusNode: focusNode);
}
int currentBottomNavIndex = 0;
List<Widget> bottomNav = [
Page1(),
Page2(),
];
onTapped(int index) {
//if(textfield not empty) {
//setState(() {
//currentBottomNavIndex = index;
//});
//}else {
focus.setFocus(context);
//}
}
#override
Widget build(BuildContext context){
return new Scaffold(
appBar: new AppBar(
title: Text('Login Page'),
),
body: bottomNav[currentBottomNavIndex],
bottomNavigationBar: BottomNavigationBar(
onTap: onTapped,
//onTap: requestFocus(context),
currentIndex: currentBottomNavIndex,
type: BottomNavigationBarType.fixed,
items: [
BottomNavigationBarItem(
icon: Icon(Icons.home),
title: Text("Page1"),
),
BottomNavigationBarItem(
icon: Icon(Icons.mail),
title: Text('Page2'),
),
],
),
);
}
}
page1.dart
class Page1 extends StatefulWidget {
final FocusNode focusNode;
const Page1({Key key, this.focusNode}) : super(key: key);
void setFocus(BuildContext context) {
print("$focusNode requestFocus...");
FocusScope.of(context).requestFocus(focusNode);
}
#override
State<StatefulWidget> createState() {
return _Page1State();
}
}
class _Page1State extends State<Page1> {
TextEditingController name1 = TextEditingController();
#override
void initState() {
super.initState();
}
#override
Widget build(BuildContext context) {
return new Scaffold(
body: SingleChildScrollView(
child: Column(
children: <Widget>[
nameApp(),
],
)
)
);
}
Widget nameApp(){
return Container(
margin: EdgeInsets.all(50.0),
//width: 185,
child: Center(
child: Row(
children: [
Container(
child: Text("Name :", style: TextStyle(fontSize: 15), ),
),
Container(
child: Flexible(
child: TextField(
focusNode: widget.focusNode,
controller: name1,
onTap: (){
name1.clear();
},
onChanged: (String str){
},
textAlign: TextAlign.center,
decoration: InputDecoration(
contentPadding: EdgeInsets.symmetric(vertical: 5),
hintText: "Full Name",
hintStyle: TextStyle(fontSize: 14),
),
),
),
),
]
)
)
);
}
}
When user click on the bottom tab, I expect to see the textfield is in focus however nothing happen.
I noticed the method in child widget has been called:
flutter: FocusNode#419f4 requestFocus...
flutter: FocusNode#419f4(FOCUSED) requestFocus...
however the textfield is still not focus.

Answer 1

I've create a simple sample project for this and its works for me just fine.
Please check out my solution:
The HomePage:
import 'package:flutter/material.dart';
import 'package:focus_node/widgets/MyInputWidget.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
FocusNode field1FocusNode = FocusNode(); //Create first FocusNode
FocusNode field2FocusNode = FocusNode(); //Create second FocusNode
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
mainAxisSize: MainAxisSize.min,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Padding(
padding: const EdgeInsets.symmetric(vertical: 8, horizontal: 35),
child: MyInputWidget(
focusNode: field1FocusNode, //Provide the first FocusNode in the constructor
hint: "Email",
onEditCompleted: (){
FocusScope.of(context).requestFocus(field2FocusNode); //Request focus
},
),
),
Padding(
padding: const EdgeInsets.symmetric(vertical: 8, horizontal: 35),
child: MyInputWidget(
focusNode: field2FocusNode, //Provide the second FocusNode
hint: "Password",
onEditCompleted: (){
FocusScope.of(context).requestFocus(field1FocusNode); //Request focus
},
),
)
],
),
),
);
}
}
The Custom Widget required focus:
class MyInputWidget extends StatefulWidget {
final FocusNode focusNode;
final String hint;
final VoidCallback onEditCompleted;
MyInputWidget({this.focusNode, this.hint, this.onEditCompleted});
#override
_MyInputWidgetState createState() => _MyInputWidgetState();
}
class _MyInputWidgetState extends State<MyInputWidget> {
#override
Widget build(BuildContext context) {
return Container(
padding: EdgeInsets.all(8),
child: TextField(
focusNode: widget.focusNode, //The FocusNode provided by the parent widget
decoration: InputDecoration(
hintText: widget.hint
),
onEditingComplete: widget.onEditCompleted,
),
);
}
}
Hope this helps.