newbie dev
Reputation: 171
Flutter: How to keep list data inside table even after switching screens back and forth?
I have a form (second screen) which is used for CRUD. When i add data, it is saved to list view as you can see on the table.
The list view is passed to (first screen) where i can iterate and see the list data with updated content.
However, when i click on go to second screen, the list view data disappears. The given 3 lists are hard coded for testing purpose.
Now, my question is that, How can i keep the data in the table and not disappear, even if i change screen back and forth multiple times. My code is as below: -
**
- Main.dart File
**
class MyApp extends StatefulWidget {
@override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
String _userInformation = 'No information yet';
void languageInformation() async {
final language = await Navigator.push(
context,
MaterialPageRoute(
builder: (context) => Episode5(),
),
);
updateLanguageInformation(language);
}
void updateLanguageInformation(List<User> userList) {
for (var i = 0; i <= userList.length; i++) {
for (var name in userList) {
print("Name: " + name.name[i] + " Email: " + name.email[i]);
}
}
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Testing List View Data From second page to first page"),
),
body: Column(
children: <Widget>[
Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
Text(_userInformation),
],
),
SizedBox(
height: 10.0,
),
ElevatedButton(
onPressed: () {
languageInformation();
},
child: Text("Go to Form"),
),
],
),
);
}
}
2. Model.dart File:
class User {
String name;
String email;
User({this.name, this.email});
}
3. Episode5 File
class Episode5 extends StatefulWidget {
@override
_Episode5State createState() => _Episode5State();
}
class _Episode5State extends State<Episode5> {
TextEditingController nameController = TextEditingController();
TextEditingController emailController = TextEditingController();
final form = GlobalKey<FormState>();
static var _focusNode = new FocusNode();
bool update = false;
int currentIndex = 0;
List<User> userList = [
User(name: "a", email: "a"),
User(name: "d", email: "b"),
User(name: "c", email: "c"),
];
@override
Widget build(BuildContext context) {
Widget bodyData() => DataTable(
onSelectAll: (b) {},
sortColumnIndex: 0,
sortAscending: true,
columns: <DataColumn>[
DataColumn(label: Text("Name"), tooltip: "To Display name"),
DataColumn(label: Text("Email"), tooltip: "To Display Email"),
DataColumn(label: Text("Update"), tooltip: "Update data"),
],
rows: userList
.map(
(user) => DataRow(
cells: [
DataCell(
Text(user.name),
),
DataCell(
Text(user.email),
),
DataCell(
IconButton(
onPressed: () {
currentIndex = userList.indexOf(user);
_updateTextControllers(user); // new function here
},
icon: Icon(
Icons.edit,
color: Colors.black,
),
),
),
],
),
)
.toList(),
);
return Scaffold(
appBar: AppBar(
title: Text("Data add to List Table using Form"),
),
body: Container(
child: Column(
children: <Widget>[
bodyData(),
Padding(
padding: EdgeInsets.all(10.0),
child: Form(
key: form,
child: Container(
child: Column(
children: <Widget>[
TextFormField(
controller: nameController,
focusNode: _focusNode,
keyboardType: TextInputType.text,
autocorrect: false,
maxLines: 1,
validator: (value) {
if (value.isEmpty) {
return 'This field is required';
}
return null;
},
decoration: new InputDecoration(
labelText: 'Name',
hintText: 'Name',
labelStyle: new TextStyle(
decorationStyle: TextDecorationStyle.solid),
),
),
SizedBox(
height: 10,
),
TextFormField(
controller: emailController,
keyboardType: TextInputType.text,
autocorrect: false,
maxLines: 1,
validator: (value) {
if (value.isEmpty) {
return 'This field is required';
}
return null;
},
decoration: new InputDecoration(
labelText: 'Email',
hintText: 'Email',
labelStyle: new TextStyle(
decorationStyle: TextDecorationStyle.solid)),
),
SizedBox(
height: 10,
),
Column(
children: <Widget>[
Center(
child: Row(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Row(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
TextButton(
child: Text("Add"),
onPressed: () {
form.currentState.save();
addUserToList(
nameController.text,
emailController.text,
);
},
),
TextButton(
child: Text("Update"),
onPressed: () {
form.currentState.save();
updateForm();
},
),
],
),
Row(
crossAxisAlignment: CrossAxisAlignment.end,
mainAxisAlignment: MainAxisAlignment.end,
children: <Widget>[
ElevatedButton(
child: Text("Save and Exit"),
onPressed: () {
form.currentState.save();
addUserToList(
nameController.text,
emailController.text,
);
Navigator.pop(context, userList);
},
),
],
),
],
),
),
],
),
],
),
),
),
),
],
),
),
);
}
void updateForm() {
setState(() {
User user = User(name: nameController.text, email: emailController.text);
userList[currentIndex] = user;
});
}
void _updateTextControllers(User user) {
setState(() {
nameController.text = user.name;
emailController.text = user.email;
});
}
void addUserToList(name, email) {
setState(() {
userList.add(User(name: name, email: email));
});
}
}
Upvotes: 0
Views: 6488
Answers (1)
Loren.A
Reputation: 5595
So instead of passing data back and forth between pages, its better to implement a state management solution so that you can access your data from anywhere in the app, without having to manually pass anything.
It can be done with any state management solution, here's how you could do it with GetX.
I took all your variables and methods and put them in a Getx class. Anything in this class will be accessible from anywhere in the app. I got rid of setState because that's no longer how things will be updated.
class FormController extends GetxController {
TextEditingController nameController = TextEditingController();
TextEditingController emailController = TextEditingController();
int currentIndex = 0;
List<User> userList = [
User(name: "a", email: "a"),
User(name: "d", email: "b"),
User(name: "c", email: "c"),
];
void updateForm() {
User user = User(name: nameController.text, email: emailController.text);
userList[currentIndex] = user;
update();
}
void updateTextControllers(User user) {
nameController.text = user.name;
emailController.text = user.email;
update();
}
void addUserToList(name, email) {
userList.add(User(name: name, email: email));
update();
}
void updateLanguageInformation() {
// for (var i = 0; i <= userList.length; i++) { // ** don't need nested for loop here **
for (var user in userList) {
print("Name: " + user.name + " Email: " + user.email);
}
// }
}
}
GetX controller can be initialized anywhere before you try to use it, but lets do it main.
void main() {
Get.put(FormController()); // controller init
runApp(MyApp());
}
Here's your page, we find the controller and now all variables and methods come from that controller.
class Episode5 extends StatefulWidget {
@override
_Episode5State createState() => _Episode5State();
}
class _Episode5State extends State<Episode5> {
final form = GlobalKey<FormState>();
static var _focusNode = new FocusNode();
// finding same instance if initialized controller
final controller = Get.find<FormController>();
@override
Widget build(BuildContext context) {
Widget bodyData() => DataTable(
onSelectAll: (b) {},
sortColumnIndex: 0,
sortAscending: true,
columns: <DataColumn>[
DataColumn(label: Text("Name"), tooltip: "To Display name"),
DataColumn(label: Text("Email"), tooltip: "To Display Email"),
DataColumn(label: Text("Update"), tooltip: "Update data"),
],
rows: controller.userList // accessing list from Getx controller
.map(
(user) => DataRow(
cells: [
DataCell(
Text(user.name),
),
DataCell(
Text(user.email),
),
DataCell(
IconButton(
onPressed: () {
controller.currentIndex =
controller.userList.indexOf(user);
controller.updateTextControllers(user);
},
icon: Icon(
Icons.edit,
color: Colors.black,
),
),
),
],
),
)
.toList(),
);
return Scaffold(
appBar: AppBar(
title: Text("Data add to List Table using Form"),
),
body: Container(
child: Column(
children: <Widget>[
// GetBuilder rebuilds when update() is called
GetBuilder<FormController>(
builder: (controller) => bodyData(),
),
Padding(
padding: EdgeInsets.all(10.0),
child: Form(
key: form,
child: Container(
child: Column(
children: <Widget>[
TextFormField(
controller: controller.nameController,
focusNode: _focusNode,
keyboardType: TextInputType.text,
autocorrect: false,
maxLines: 1,
validator: (value) {
if (value.isEmpty) {
return 'This field is required';
}
return null;
},
decoration: InputDecoration(
labelText: 'Name',
hintText: 'Name',
labelStyle: new TextStyle(
decorationStyle: TextDecorationStyle.solid),
),
),
SizedBox(
height: 10,
),
TextFormField(
controller: controller.emailController,
keyboardType: TextInputType.text,
autocorrect: false,
maxLines: 1,
validator: (value) {
if (value.isEmpty) {
return 'This field is required';
}
return null;
},
decoration: InputDecoration(
labelText: 'Email',
hintText: 'Email',
labelStyle: new TextStyle(
decorationStyle: TextDecorationStyle.solid)),
),
SizedBox(
height: 10,
),
Column(
children: <Widget>[
Center(
child: Row(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Row(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
TextButton(
child: Text("Add"),
onPressed: () {
form.currentState.save();
controller.addUserToList(
controller.nameController.text,
controller.emailController.text,
);
},
),
TextButton(
child: Text("Update"),
onPressed: () {
form.currentState.save();
controller.updateForm();
},
),
],
),
Row(
crossAxisAlignment: CrossAxisAlignment.end,
mainAxisAlignment: MainAxisAlignment.end,
children: <Widget>[
ElevatedButton(
child: Text("Save and Exit"),
onPressed: () {
form.currentState.save();
controller.updateLanguageInformation(); // all this function does is print the list
Navigator.pop(
context); // don't need to pass anything here
},
),
],
),
],
),
),
],
),
],
),
),
),
),
],
),
),
);
}
}
And here's your other page. I just threw in a ListView.builder wrapped in a GetBuilder<FormController> for demo purposes. It can now be stateless.
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Testing List View Data From second page to first page"),
),
body: Column(
children: <Widget>[
Expanded(
child: GetBuilder<FormController>(
builder: (controller) => ListView.builder(
itemCount: controller.userList.length,
itemBuilder: (context, index) => Row(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: [
Text(controller.userList[index].name),
Text(controller.userList[index].email),
],
),
),
),
),
SizedBox(
height: 10.0,
),
ElevatedButton(
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => Episode5(),
),
);
},
child: Text("Go to Form"),
),
],
),
);
}
}
As your app expands you can create more controller classes and they're all very easily accessible from anywhere. Its a way easier and cleaner way to do things than manually passing data around everywhere.
Upvotes: 4
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