Contents

Generic types in PopScope

Contents

Summary

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Added a generic type to the PopScope class and replaced the onPopInvoked with a new method onPopInvokedWithResult. The new method takes a boolean didPop and a result as position parameters.

Also replaced the Form.onPopInvoked with Form.onPopInvokedWithResult for the same reason.

Context

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Previously, PopScope didn't have a way to access the pop result when onPopInvoked was called. The generic type is added to the PopScope class so that the new method onPopInvokedWithResult can access the type-safe result.

Description of change

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Added a generic type (<T>) to the PopScope class and a new method onPopInvokedWithResult. The onPopInvoked property was deprecated in favor of onPopInvokedWithResult.

Also added a new method onPopInvokedWithResult to Form to replace onPopInvoked.

Migration guide

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Code before migration:

dart
import 'package:flutter/material.dart';

void main() {
  runApp(
    MaterialApp(
      navigatorKey: nav,
      home: Column(
        children: [
          Form(
            canPop: false,
            onPopInvoked: (bool didPop) {
              if (didPop) {
                return;
              }
              launchConfirmationDialog();
            },
            child: MyWidget(),
          ),
          PopScope(
            canPop: false,
            onPopInvoked: (bool didPop) {
              if (didPop) {
                return;
              }
              launchConfirmationDialog();
            },
            child: MyWidget(),
          ),
        ],
      ),
    ),
  );
}

Code after migration:

dart
import 'package:flutter/material.dart';

void main() {
  runApp(
    MaterialApp(
      navigatorKey: nav,
      home: Column(
        children: [
          Form(
            canPop: false,
            onPopInvokedWithResult: (bool didPop, Object? result) {
              if (didPop) {
                return;
              }
              launchConfirmationDialog();
            },
            child: MyWidget(),
          ),
          PopScope<Object?>(
            canPop: false,
            onPopInvokedWithResult: (bool didPop, Object? result) {
              if (didPop) {
                return;
              }
              launchConfirmationDialog();
            },
            child: MyWidget(),
          ),
        ],
      ),
    ),
  );
}

The generic type should match the generic type of the Route that the PopScope is in. For example, if the route uses int as its generic type, consider using PopScope<int>.

If the PopScope widgets are shared across multiple routes with different types, you can use PopScope<Object?> to catch all possible types.

Timeline

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Landed in version: 3.22.0-26.0.pre
In stable release: 3.24.0

References

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API documentation:

Relevant issue:

Relevant PR:

Unless stated otherwise, the documentation on this site reflects the latest stable version of Flutter. Page last updated on 2024-08-06. View source or report an issue.