Flutter: How to Finish an Async Function on Tap and Redirect to Another Component

Introduction

In Flutter, it is common to have asynchronous operations, such as fetching data from an API or performing complex calculations. Sometimes, you may need to finish an async function when a button is tapped and then redirect to another component. However, this can lead to issues with unmounting or mounting the component. In this tutorial, we will explore how to handle this situation.

Creating the Button

First, let’s create a button widget that will trigger the async function and redirect to another component. Here is an example code snippet:

FlatButton(
  onPressed: () {
    _onButtonTap();
  },
  child: Text('Finish and Redirect'),
),

Handling the Async Function

Next, we need to handle the async function within the _onButtonTap function. To ensure a smooth flow without any mounting or unmounting issues, we can use a combination of StatefulWidget, setState, and Navigator. Here is an example implementation:

class MyComponent extends StatefulWidget {
  @override
  _MyComponentState createState() => _MyComponentState();
}

class _MyComponentState extends State<MyComponent> {
  bool _isLoading = false;

  Future<void> _onButtonTap() async {
    setState(() {
      _isLoading = true;
    });

    await _finishAsyncFunction();

    setState(() {
      _isLoading = false;
    });

    Navigator.push(
      context,
      MaterialPageRoute(
        builder: (context) => OtherComponent(),
      ),
    );
  }

  Future<void> _finishAsyncFunction() async {
    await Future.delayed(Duration(seconds: 2));
    // Perform any necessary asynchronous operations
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: _isLoading
          ? Center(child: CircularProgressIndicator())
          : Container(
              // Your component UI here
            ),
    );
  }
}

In this example, we have a bool variable _isLoading that indicates whether the async function is currently running. When the button is tapped, _onButtonTap is called, which sets _isLoading to true to display a loading indicator. Then, _finishAsyncFunction is called to complete the async function. After that, _isLoading is set to false, and the Navigator is used to redirect to the OtherComponent.

Conclusion

By using a combination of StatefulWidget, setState, and the Navigator class, we can handle async functions in Flutter onTap events and redirect to another component without any unmount or mount issues. This ensures a smooth user experience while performing async operations.