flutter:: Can a variable be used in another file? - flutter

Question

home.dart
class HomePage extends StatefulWidget {
#override
_HomePageState createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
late Directory? appDir;
late List<String>? records;
record.dart
class Records extends StatefulWidget {
final List<String> records;
const Records({
Key? key,
required this.records,
}) : super(key: key);
#override
_RecordsState createState() => _RecordsState();
}
app.dart
class App extends GetView<AppController>{
const App({Key? key}) : super(key: key);
static const PrimaryColor1 = const Color(0xFF708FF8);
#override
Widget build(BuildContext context){
return Scaffold(
body: Obx(() {
switch(RouteName.values[controller.currentIndex.value]) {
case RouteName.Home:
return Home();
break;
case RouteName.Record:
return Record(records: records);
I need to return Record(records: records) in app.dart. The variable records is in home.dart. Is there a way to use the variable records in app.dart?
+) I tried changing it as follows, but 'recordnull' was printed.
home.dart
class video_Body extends StatefulWidget {
video_Body({Key? key, required this.index}) : super(key: key);
#override
_video_Body createState() => _video_Body();
int index;
static List<String>? records;
}
class _video_Body extends State<video_Body> {
List<String>? get record => video_Body.records;
app.dart
if(video_Body.records == null) print('recordnull');
return Record(records: video_Body.records);

Answer 1

There are several ways to do what you want to do, here are the two simplest ones I could think of:
1. Store the variable somewhere else.
It is hard to explain how to do this because I have very little information about what the home page is doing to the list of records, but the general idea is declare the list of records on the app.dart file and pass the value of the list into the Home class.
To do this, you will probably have to declare some sort of callback for when the Home class wants to edit the list, I will give you an example:
In this example, we have a button widget that displays a number, and when you press the button it increases the value of the number, and we want to access the current value of the number.
First I will show you the equivalent of your problem:
Button:
class MyButton extends StatefulWidget {
...
}
class _MyButtonState extends State<MyButton> {
int value = 0;
#override
Widget build(BuildContext) {
return ElevatedButton(
child: Text(value.toString()),
onPressed: () => setState(() => value++),
);
}
}
Home:
class Home extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Column(
children: [
MyButton(),
Text(buttonText), // how do we access the button text?????
]
);
}
}
And now, with the solution:
Button:
class MyButton extends StatelessWidget {
MyButton({required this.value, required this.onChange});
final void Function(int) onChange;
final int value;
#override
Widget build(BuildContext) {
return ElevatedButton(
child: Text(value.toString()),
onPressed: () => onChange(value +1),
);
}
}
Home:
class Home extends StatefulWidget {
...
}
class _HomeState extends State<Home> {
int value = 0;
#override
Widget build(BuildContext context) {
return Column(
children: [
MyButton(onChange: (v) => setState(() => value=v), value: value),
Text(value.toString()),
]
);
}
}
Of course, this solution may not work for you depending on the situation.
2. Use a static class
The idea here is to move the variable you want to access into a static class, first you need to make a class with a static variable you want to access:
class RecordsService {
static List<String>? records;
}
Because it is static, you can access it from anywhere, so on home, make the following changes:
Before:
late List<String>? records;
After:
List<String>? get records => RecordService.records;
and to access the value on app:
return Record(records: RecordService.records);
Hopefully one of these solutions solves your use case.