flutter dynamic navigation bar: identify which icon/button is tapped

Question

I am creating a dynamic list of BottomNavigationBarItem and assigning it to 'items' of BottomNavigationBar. So based on a condition (here is my case, checks and add one more BottomNavigationBarItem if it is not billed. So the number of Icons displayed change. Normally for a fixed number of items, ontap provide index of the icon tapped. As the order/sequence of icons change, their index also differs.

Now how do I read the label of selected BottomNavigationBarItem and respond in onTap handler instead of tapped index value ?

(Of course in this particular case, I can add the additional button as last one and done with. Need a better solution.)

  List<BottomNavigationBarItem> getNavbarItems() {
    List<BottomNavigationBarItem> navItems = [];
    navItems.add(
      const BottomNavigationBarItem(
          icon: Icon(Icons.delete_outline,), label: 'Delete',),
    );
    if (widget.invStatus.isBilled == 0) {
      navItems.add(
        const BottomNavigationBarItem(
            icon: Icon(Icons.receipt), label: 'Bill it ?'),
      );
    }
    navItems.add(
      const BottomNavigationBarItem(
          icon: Icon(Icons.category_rounded), label: 'Add a Product !'),
    );
    return navItems;
  }

Thanks.

Answer 1

If I understand you correctly, you can use the following approach to get the "label".

Call:

getNavbarItems()[index].label

And have a button to dynamically toggle isBilled.

Complete example:

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: Nav(),
        ),
      ),
    );
  }
}

class Nav extends StatefulWidget {
  @override
  createState() => NavState();
}

class NavState extends State<Nav> {
  var _selectedIndex = 0;
  var billIt = false;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Nav'),
      ),
      body: Center(
        child: TextButton(
          child: Text('Toggle `billIt`'),
          onPressed: () {
            setState(() {
              billIt = !billIt;
            });
          },
        ),
      ),
      bottomNavigationBar: BottomNavigationBar(
        currentIndex: _selectedIndex,
        items: getNavbarItems(),
        onTap: (int index) {
          setState(() {
            _selectedIndex = index;
            print('label: ${getNavbarItems()[index].label}');
          });
        },
      ),
    );
  }

  List<BottomNavigationBarItem> getNavbarItems() {
    List<BottomNavigationBarItem> navItems = [];

    navItems.add(
      const BottomNavigationBarItem(
        icon: Icon(
          Icons.delete_outline,
        ),
        label: 'Delete',
      ),
    );

    if (billIt) {
      navItems.add(
        const BottomNavigationBarItem(
            icon: Icon(Icons.receipt), label: 'Bill it ?'),
      );
    }
    navItems.add(
      const BottomNavigationBarItem(
          icon: Icon(Icons.category_rounded), label: 'Add a Product !'),
    );
    return navItems;
  }
}