Passing data between Widgets without using Navigator? - flutter

Question

I've some struggling with flutter.
I've two widget Details screen so in the first Details, I have a list and I want to send it to the second Screen without using navigator.
So if there is anyone who can help me I will be very thankful.
Details :
List<String> _instructions = [];
class Details extends StatefulWidget {
#override
_DetailsState createState() => new _DetailsState();
}
class _DetailsState extends State<Details> {
Expanded(
child: Container(
margin: EdgeInsets.all(3),
child: OutlineButton(
highlightElevation: 21,
color: Colors.white,
shape: StadiumBorder(),
textColor: Colors.lightBlue,
child: Text(
'ENVOYER',
style: TextStyle(
fontSize: 16,
fontWeight: FontWeight.bold,
fontStyle: FontStyle.normal,
color: Colors.lightBlue,
),
),
borderSide: BorderSide(
color: Colors.lightBlue,
style: BorderStyle.solid,
width: 1),
onPressed: () {
},
),
),
),
}}
so what I want is that,when I press the button I will send my list to the next widget without using navigator.

Answer 1

you can use the sharedpreferance which is the simple xml that belongs to the application. And this is how you can set it
Future<bool> setStringList(String key, List<String> value) =>
_setValue('StringList', key, value);
Future<bool> setStringList (
String key,
List<String> value
)
For more info here is a link
And you can get your List by
List<String> getStringList(String key) {
List<Object> list = _preferenceCache[key];
if (list != null && list is! List<String>) {
list = list.cast<String>().toList();
_preferenceCache[key] = list;
}
return list;
}
Also you can use sqflite

Answer 2

Suppose you have two pages, namely 'page1.dart' and 'page2.dart', both want to access the same list:
Create another dart file 'GlobalVariables.dart', inside this file, create a class gv.
Inside this class gv, create a static list by using:
static List <String> listAnyList = [];
import 'GlobalVariables.dart' in the 2 pages that need to access this list.
Now, in page1.dart and page2.dart,
you can use gv.listAnyList to access the 'Global List'.
Use 'Global Static Variables' if a variable is needed in many dart files, e.g. the 'User ID', then you can simply use gv.strUserID to access it in any pages you want.

Answer 3

I think a more appropriate approach should be similar to how android fragments connect to each other using bloc pattern or master-details flow.
I created an example repository to show the complete concept.
In short, the idea is to create a class with StreamController inside. Both widgets will have a reference to bloc instance. When the first widget wants to send data to the second it adds a new item to Stream. The second listen to the stream and updates its content accordingly.
Inside bloc:
StreamController<String> _selectedItemController = new BehaviorSubject();
Stream<String> get selectedItem => _selectedItemController.stream;
void setSelected(String item) {
_selectedItemController.add(item);
}
First fragment:
class FragmentList extends StatelessWidget {
final Bloc bloc;
const FragmentList(
this.bloc, {
Key key,
}) : super(key: key);
#override
Widget build(BuildContext context) {
return StreamBuilder(
stream: bloc.selectedItem,
initialData: "",
builder: (BuildContext context, AsyncSnapshot<String> screenType) {
return ListView.builder(
itemBuilder: (context, index) {
return ListTile(
selected: bloc.items[index] == screenType.data,
title: Text(bloc.items[index]),
onTap: () {
bloc.setSelected(bloc.items[index]);
},
);
},
itemCount: bloc.items.length,
);
},
);
}
}
The second fragment:
class FragmentDetails extends StatelessWidget {
final Bloc bloc;
const FragmentDetails(
this.bloc, {
Key key,
}) : super(key: key);
#override
Widget build(BuildContext context) {
return Center(
child: StreamBuilder(
initialData: "Nothing selected",
stream: bloc.selectedItem,
builder: (BuildContext context, AsyncSnapshot<String> screenType) {
final info = screenType.data;
return Text(info);
},
),
);
}
}