How to pass maps in lists (dart)-CodePudding

I'm trying to form a Container with Text objects in Flutter. The data for those Text objects are coming from a List. I'm relatively new to Dart and Flutter, so i can't figure out why i can only pass strings in a map() method and not maps.

child: Column(
         children: tasks.map((value) => ColumnChild(value['title'])).toList()
       )

The code above basically works. However, i want to just pass only the value in, but that errors.

This is where i create the object:


class ColumnChild extends StatelessWidget {
  String title;

  ColumnChild(this.title);

  @override
  Widget build(BuildContext context) {
      print(title);
    return Container(
      width: double.infinity,
      height: 50 ,
      child: Column(
        children: [
          Text(title)
        ],
      )
    );
  }
}

Thanks in advance!

CodePudding user response：

ColumnChild asks for a string called title. If you give it a map, flutter gets confused.

Imagine maps are dictionaries and strings are words. Your widget ColumnChild asked for a word and you gave it the whole dictionary, without teaching it how to look up a word.

Let's teach it how to look up a word:

class ColumnChild extends StatelessWidget {
  // you can put any name instead of data but don't forget to replace it in your code
  final Map<String, dynamic> data;

  const ColumnChild(this.data, {Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SizedBox(
        width: double.infinity,
        height: 50,
        child: Column(
          children: [Text(data['title'] ?? 'not found')],
        ));
  }
}

Now instead of coming to you asking for a word, it asks for the dictionary and looks up the words by itself and you can do this:

child: Column(
         children: tasks.map((value) => ColumnChild(value)).toList()
       )

CodePudding user response：

Instead of using the .map(), You could loop through the list and use the Strings directly

     Column(
       children: [
         for(var a in tasks)
          Text(a)
      ),

Or You use a listView.builder

     ListView.builder(
     itembuilder: (context,index){
       return Text(tasks[index])
             },
     itemCount: tasks.length
        )