Question 193928 in Flutter Question posted in
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How to call function in Widget from class of another file in Dart / Flutter?

I want data in a widget to be updated by calling setState() in the widget from another file which retrieves the updated data from a database (Please note that the displayed code is heavily reduced to only display my problem).
For this I think the easiest thing is to call a function with setState() inside of it, however there could be other ways to do this that I don’t know of and would be happy to hear.
My problem is, that I don’t know how to call that function: I want to call the function ‘foo’ inside of the stateful Widget ‘testWidget’ from a class ‘testClass’ in another file.
Here is the code of the first file:

class testWidget extends StatefulWidget {
  const testWidget({super.key});

  @override
  State<testWidget> createState() => _testWidgetState();
}

class _testWidgetState extends State<testWidget> {
  int value = 0;
  @override
  Widget build(BuildContext context) {
    return Container();
  }
  void foo(int x){
    setState(() {
      value = x;
    });
  }
}

foo() should be called from this class:

import 'first_file.dart';

class testClass {
  int x = 6;
  void callFunctionInWidget(){
    // Something like: testWidget.foo(x);
  }
}

How can I achieve this?
The widget is displayed the whole time, i just want to update its data from another file.

I looked at many other questions on here, which are similar (e.g. call function of widget from parent widget), but I got no solution to work.

Tags:

2

Answers


  1. 0

    1. How to call a method in the state class of a stateful widget:

    To update the data in a widget by calling setState() from another file, you can access the state class of the widget using a GlobalKey.
    Depending on your use case, you can define different types of keys.
    For example, You can Define a global key as a global variable, which you can have access everywhere :

    GlobalKey<testWidget> testWidgetKey = GlobalKey();

    Pass that key to your TestWidget’s constructor.
    TestWidget(key:testWidgetKey)
    Finally, you can call the foo() function:

    textWidgetKey.currentState?.foo();

    2. State Management in Flutter

    you’re looking for a state management solution in flutter.
    You can find more data about different approaches here on Flutter’s official website, or many other blogs from the community.

    Login or Signup to reply.
  2. 0

    I guess your approach is not right. If you want to access a database then you should make a specific dart file for that. Any function related to that data should be inside that file. You can call any method inside that file by using its object.

    For example I have a method connect() to connect to my dataase.

    class Database{

    Future<>connect()async{
    }
}

    This method is in my database.dart file. I can access this from any other file by just importing

    import 'package:project_name/database.dart';

    and making an object of the class Database

    Database db = Database();
await db.connect();
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