How do I check if the current widget is in the top-most context?

Question

I have a widget which runs a function every minute when it's active. However, I don't want this function to run when I have pushed another page above the widget, so I wanted to wrap the function in a conditional which is only true when the current widget is in the top-most context (i.e., there are no pages which have been pushed above it).

I tried to find a way of doing this, but was unsuccessful, so any guidance or suggestions would be appreciated.

Thank you.

Answer 1

You can use the ModalRoute.of(context) to check if the current route is the top-most route in the navigator stack.

import 'dart:async';

import 'package:flutter/material.dart';

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  late Timer timer;

  @override
  void initState() {
    super.initState();
    timer = Timer.periodic(Duration(minutes: 1), (timer) {
      if (ModalRoute.of(context)?.isCurrent ?? false) {
        // Run your function here
        print('Some function executed here');
      }
    });
  }

  @override
  void dispose() {
    timer.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('My Widget'),
      ),
      body: Center(
        child: Text('My Widget Body'),
      ),
    );
  }
}

In the above example, we check if the route we are in is the current route by doing ModalRoute.of(context)?.isCurrent. When that is true, the periodic function will only run.