i want to know how to pass data from one class to another class.
Main CLASS
void WhenPageScroll() {
int USERID = int.parse(complexTutorial.data[_pageController.page.toInt()].userId);
print("ID $USERID");
Tut(int.parse(complexTutorial.data[_pageController.page.toInt()].userId));
}
Tut Class
class Tut extends StatefulWidget {
Tut(this.USERID);
final int USERID;
#override
_TutState createState() => _TutState();
}
class _TutState extends State<Tut>{
#override
Widget build(BuildContext context) {
return Container(child: LoadTut(),);
}
LoadTut(){
return Center(child: Text("CENTER TEXT WITH " + widget.USERID.toString()));
}
}
i am using this method but no working how can i do that on page Scrolled?
Note : when i am using setState then whole page are reload but i want to reload only Tut on Scrolled.
Thanks Team.
Related
My first Flutter development with GetX. Now encounter a problem.
I have a ListView where the items are all encapsulated Class.
The requirement now is to create an obs List as a data source. The elements in the List are all models.
I now want to pass the model in the List to the item, and click on the item to pass it to the next page for data modification. what should I do?
I am like this
`
Controller：
class FindQADetailController extends GetxController {
var detailEntity = QADetailEntity().obs;
}
Page：
class FindQAPage extends StatefulWidget {
const FindQAPage({Key key}) : super(key: key);
#override
State<FindQAPage> createState() => _FindQAPageState();
}
class _FindQAPageState extends BasePageMixin<FindQAPage, FindQAPresenter>
with SingleTickerProviderStateMixin
implements FindQAIView {
final findQAController = Get.put(FindQAController());
#override
void initState() {
super.initState();
_refresh();
}
#override
Widget build(BuildContext context) {
return RezaAppContainer(
childWidget: Obx(() => DeerListView(
itemCount: findQAController.listData.length,
onRefresh: _refresh,
loadMore: _loadMore,
hasMore: findQAController.hasMore,
itemBuilder: (_, index) {
var entity = findQAController.listData[index];
return FindItemQAPage(entity);
})),
);
}
Item：
class FindItemQAPage extends StatefulWidget {
FindItemQAPage(this.entity, {Key key}) : super(key: key);
QAEntity entity;
#override
State<FindItemQAPage> createState() => _FindItemQAPageState();
}
class _FindItemQAPageState
extends BasePageMixin<FindItemQAPage, FindItemQAPresenter>
with SingleTickerProviderStateMixin
implements FindItemQAIView {
FindItemQAController findItemQAController = Get.put(FindItemQAController());
#override
void initState() {
super.initState();
findItemQAController.entity.value = widget.entity;
}
}
`
I want the elements in the array in the first page to be passed to the item and the next page, and the data modifications made on the next page to be passed to the item in the first page.
Passing Data from 1st Screen to 2nd Screen
You can pass any data using arguments parameters in navigation methods
Get.to(ScreenName(),arguments: PASS_DATA);
If you are doing navigation with routes still you can pass data
Get.toNamed(RoutesName, arguments: PASS_DATA);
For navigate data back from 2nd screen to 1st screen you can user result property.
Get.back(result:PASS_DATA);
Pass data from 1st screen to 2nd screen & vice versa.
1st screen controller
import 'package:get/get.dart';
class FirstController extends GetxController {
/// Navigation method.
Future<void> btnNavigateTap() async {
//.... Using Get.toNamed method || use this if you are using routeName
//.... Pass Data from 1st screen to 2nd screen
Get.toNamed(
SeconScreenRouteName,
arguments: {
"user": "Jems",
"emails": ["abc#gmail.com", "pqr#gmail.com"],
},
);
//.... Using Get.to method
//.... Pass Data from 1st screen to 2nd screen
Get.to(
SecondScreen(),
arguments = {
"user": "Jems",
"emails": ["abc#gmail.com", "pqr#gmail.com"],
},
);
//.... Get Data from 2nd screen to 1st screen
final result = await Get.to(
SecondScreen(),
arguments = {
"user": "Jems",
"emails": ["abc#gmail.com", "pqr#gmail.com"],
},
);
}
}
2nd screen controller to access data.
import 'package:get/get.dart';
class SecondController extends GetxController {
late String user;
late List<String> emails;
dynamic argumentData;
#override
void onInit() {
super.onInit();
user = argumentData['user'];
emails = argumentData['emails'];
}
void btnBackTap(){
//... Passing data to previous screen.
Get.back(result:{
"user":"Jack",
});
}
}
For more details about navigation & parsing data using getX check this reference link
How do I access the variable "selectedTag" from this statefulWidget:
class _AlertDialogOneState extends State<AlertDialogOne> {
Item selectedTag;
...
}
}
inside this statelessWidget :
class CardTile extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Container(...
Pass it as parameter,
class CardTile extends StatelessWidget {
final Item selectedTag;// Add this
CardTile(this.selectedTag); // Add this
#override
Widget build(BuildContext context) {
return Container(...
To pass this variable, you have multiple ways:
Pass it as a constructor when u navigate to this class using your navigator
Navigator.push(
context,
MaterialPageRoute(builder: (context) => CardTile(selectedTag)),
);
class CardTile extends StatelessWidget {
Item selectedTag;
CardTile(this.selectedTag);
#override
Widget build(BuildContext context) {
return Container(...
Use a state management like provider
class ProviderData with ChangeNotifier {
Item selected;
void changeSelection(newSelect) {
selected = newSelect;
changeNotifier();
}
}
and inside any class you need call this:
final providerData = Provider.of<ProviderData>(context);
so you can access the variable or change it using this instance like this:
final variable = providerData.selected;
providerData.changeSelection(newValue);
print(variable);
hope this help but i see that it is better to pass it through the constructor if you are not using a state managemnt, however i just gave you an example for illustration
I have a drop down class and a list view. I want to change the state of list view when the drop down item is changed. To do so, i have to setState of list from dropdown class.I learnt about callback function and was trying to implement it. But I got an error.
My Code for drop down class:
class DropDown extends StatefulWidget {
final Function _callBack;
DropDown({#required void callBack()}) :
_callBack = callBack;
#override
_DropDownState createState() => _DropDownState();
}
Code for ListLayout is here:
class ListLayout extends StatefulWidget {
DropDown(dropDownItemChanged );//Error comes here saying 'DropDown' must have a method body
// because 'ListLayout' isn't abstract. Try making 'ListLayout' abstract, or adding a body to
//'DropDown'.
#override
_ListLayoutState createState() => _ListLayoutState();
}
class _ListLayoutState extends State<ListLayout> {
void dropDownItemChanged (String data) {
setState(() {
....
}
}
});
}
#override
Widget build(BuildContext context) {
return ....;
}
}
I would be grateful if somebody could answer this
I am sorry, I was not supposed to instantiate DropDown from ListLayout , because DropDown is not a child of ListLayout. May be this helps someone.
I have a Flutter App with Provider as a State Manager. The ChangeNotifierProvier is at the very top of my app (ie. above MaterialApp widget).
I have a ChangeNotifier class as follows:
class AmountManager extends ChangeNotifier {
String amount;
void changeAmount(String newAmount) {
amount = newAmount;
notifyListeners();
}
}
Then I have another class with a TextField :
class MyTextField extends StatelessWidget {
#override
Widget build(BuildContext context) {
return TextField(
//some decorations here
onChanged(value) {
Provider.of<AmountManager>(context).changeAmount(value);
},
);
}
}
And in another class under the Main App, I call the amount variable:
class MyText extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Text(
Provider.of<AmountManager>(context).amount,
);
}
}
The problem is the Provider.of(...) method cannot be called. I watched some tutorials and couldn't find out the reason behind it. If I use static text instead of the AmountManager object, it works. The program only uses the initial value of amount in MyText class.
What do you think I'm wrong with?
Thank you in advance,
You need listen: false when you use Provider.of() in onChanged.
onChanged: (value) {
Provider.of<AmountManager>(context, listen: false).changeAmount(value);
},
See this for details.
Once the StatefulWidget dispose, (item out of screen) how to retrieve the state of the StatefulWidget?
I'm actually set a animatedlist but I think it's the same probleme. May be update the list might solved the probleme. But how?
I just want the same state.
You'll want the State that needs to be preserved to use AutomaticKeepAliveClientMixin.
Here's an example:
class Foo extends StatefulWidget {
#override
FooState createState() {
super.build(context);
return new FooState();
}
}
class FooState extends State<Foo> with AutomaticKeepAliveClientMixin {
#override
Widget build(BuildContext context) {
return Container(
);
}
#override
bool get wantKeepAlive => true;
}
Such Foo widget will preserve its state even if it leaves the screen inside a ListView