flutter - 如何在 Flutter 中解析数据列表项下拉列表

Question

我有代码下拉菜单，但我会解析列表项 制作下拉菜单模板，所以我只更改列表项部分。

                child: DropdownButton<String>(
                  isExpanded: true,
                  icon: Icon(Icons.keyboard_arrow_down),
                  value: dropdownValue,
                  onChanged: (String newValue) {
                    setState(() {
                      dropdownValue = newValue;
                    });
                  },
                  items: <String>['Instagram', 'Two', 'Free', 'Four']
                      .map<DropdownMenuItem<String>>((String value) {
                    return DropdownMenuItem<String>(
                      value: value,
                      child: Text(value),
                    );
                  }).toList(),

Answer 1

这就是你想要做的吗？

class DropDownTest extends StatefulWidget {
  @override
  _DropDownTestState createState() => _DropDownTestState();
}

class _DropDownTestState extends State<DropDownTest> {
  MenuItem dropdownValue;

  @override
  Widget build(BuildContext context) {
    return DropdownButton<MenuItem>(
        isExpanded: true,
        icon: Icon(Icons.keyboard_arrow_down),
        value: dropdownValue,
        onChanged: (MenuItem newValue) {
          setState(() {
            dropdownValue = newValue;
          });
        },
        items: items.map<DropdownMenuItem<MenuItem>>((MenuItem value) {
          return DropdownMenuItem<MenuItem>(
            value: value,
            child: Text(value.name),
          );
        }).toList());
  }
}

class MenuItem {
  final int id;
  final String name;

  const MenuItem(this.id, this.name);
}

const List<MenuItem> items = [
  MenuItem(1, 'ONE'),
  MenuItem(2, 'TWO'),
  MenuItem(3, 'THREE'),
  MenuItem(4, 'FOUR'),
];