Flutter; get index number for a list

Question

In my app, I have a list of 'goals'.

On the main page, there is a list.map than makes a button for each goal.

These buttons contain the name and description of the goal.

When the user clicks on them, they're taken to another page (goalPage)

When the goalPage loades, it needs to display the goal the user clicked on. I was thinking that if i could get acces to the list-idex-number of the goal, in the goalPage, it would work, because all the info I need is in the list. But I don't now how to get that index-number, spesially because it can change, it the user deletes a goal or adds a new one.

List (on MainPage):

List<Goal> goals = [
   Goal(title: 'Example goal', description: 'this is an example goal'),
];

Display of goals (on MainPage):

Column(
   children: goals.map((goal) => GoalTemplate(goal: goal)).toList(),
),

goal button template (on goalTemplate file):

class GoalTemplate extends StatefulWidget {

  final Goal goal;
  GoalTemplate({this.goal});

  @override
  _GoalTemplateState createState() => _GoalTemplateState();
}

class _GoalTemplateState extends State<GoalTemplate> {

  int listIndex;

  void navToGoalPage () async {
    Navigator.of(context).push(MaterialPageRoute(
      builder: (context) => GoalPage(),));
  }

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: () {
        setState(() {
          listIndex = goals.indexOf();
        });
        navToGoalPage();
      },
      child: Column(
              children: <Widget>[
                Text(widget.goal.title),
                Text(widget.goal.description),
              ],
            ),
    );
  }
}

(The goal page doesn't work at all, well that's kinda why im asking here, I need to have a page, just with a Varioble of the current-index-value (not the total number of items in the list))

Dung Ngo · Accepted Answer · 2020-10-29 08:30:09Z

1

Try changing from using map to using for function:

Column(
  children: [
    for(int index = 0; index < goals.length; index++) // goals[index] is what you want to get
      GoalTemplate(goal: goal)
  ]
)

answered Oct 29, 2020 at 8:30

Dung Ngo

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