Access Object Data in Flutter

Question

I'm new to Flutter and trying to get some basics done. I would like to access data from an object on several places within my code.

I'm most likely mixing up scope or variable types within oo code. So far I only used basic coding using javascript or php and never played to much with objects and stuff.

Please see my sample code below:

class _APPS extends State<APP>
    with SingleTickerProviderStateMixin {

  final pages = {
    "events": {
      "title": "Events",
      "icon": Icon(Icons.event),
      "page": EventsSite(),
    },
    "news": {
      "title": "News",
      "icon": Icon(Icons.message),
      "page": NewsSite(),
    },
    "favorites": {
      "title": "Favorites",
      "icon": Icon(Icons.favorite),
      "page": EventsSite(),
    },
    "profile": {
      "title": "Profile",
      "icon": Icon(Icons.account_circle),
      "page": EventsSite(),
    },
  };

  Widget build(BuildContext context) {
    return MaterialApp(
      home: Builder(
        builder: (context) => Scaffold(
          body: PageView(
            controller: _pageController,
            //physics: NeverScrollableScrollPhysics(),
            onPageChanged: _onPageChanged,
            children: [
              pages[0]['page'], <=== Here is what i'm trying to do
              NewsSite(),
              Icon(Icons.directions_bike),
            ],
          ),
          bottomNavigationBar: BottomNavigationBar(
            type: BottomNavigationBarType.fixed,
            showUnselectedLabels: false,
            backgroundColor: _colorBackgroundBright,
            unselectedItemColor: Colors.white,
            selectedItemColor: _colorHighlight,
            selectedLabelStyle: TextStyle(fontSize: 10.0),
            iconSize: 20,
            currentIndex: _selectedIndex,
            onTap: _onItemTapped,
            items: const <BottomNavigationBarItem>[
              BottomNavigationBarItem(
                icon: Icon(pages['Events']['icon']), <=== Here is what i'm trying to do
                title: Text(pages[0]['title']), <=== Here is what i'm trying to do
              ),
              BottomNavigationBarItem(
                icon: Icon(Icons.message),
                title: Text('News'),
              ),
              BottomNavigationBarItem(
                icon: Icon(Icons.favorite),
                title: Text('Favorites'),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

How to access the values of the defined object (in this case the object pages) from within my flutter code. I've add an image where you should see the issue I'm having with accessing the object data (just an example tho) — Stefan
– Stefan, Commented Sep 29, 2019 at 19:50

creativecreatorormaybenot · Accepted Answer · 2019-09-29 21:39:22Z

4

You need to access your Map properly.

Instead of pages[0] or pages['Events'], you want to specify the correct key:

pages['events']

Map keys are case-sensitive because they use the equals operator.

You cannot access a Map when creating a const. So remove const at const <BottomNavigationBarItem>[:

<BottomNavigationBarItem>[
  ...
]

Additionally, for the icon you need to use pages['events']['icon'].

edited Sep 29, 2019 at 21:39

answered Sep 29, 2019 at 18:55

creativecreatorormaybenot

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2 Comments

Stefan Over a year ago

True, but that didn't solve the issue: I won't be able to fetch the data even with lower case syntax

Stefan Over a year ago

Thank you, what a minor issue :)

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