Flutter：在小部件调用中使用参数（图标）

Question

I am new to flutter. I have extracted a widget in order to create signin-buttons. I want to pass a parameter which specifies the icon which should be used, however I cannot add my parameter inside the method call of the Icon widget. How can this be managed?

The error appears inside the Icon-Widget. Code:

  class LoginButtonIcon extends StatelessWidget {
  final String iconName;

  const LoginButtonIcon({Key key, @required this.iconName}) : super(key: key);
 @override
  Widget build(BuildContext context) {
    return RaisedButton(
        onPressed: () => "Pressed",
        child: Row(
          mainAxisAlignment: MainAxisAlignment.start,
          children: <Widget>[
            Icon(
              Icons.iconName,
              color: Colors.white,
            ),
            SizedBox(
              width: 15,
            ),
            Text("RaisedButton",
                style: TextStyle(color: Colors.white, fontSize: 14)),
          ],
        ),
        color: Colors.black54);
  }
}

Answer 1

iconName type should not be String , it should be IconData and you should pass full icon like this Icons.add

Answer 2

you are on the right way. now declare a function which return a Icon-Widget. In the function use a switch-case, to return a different Icon depending on the String which is delivered as parameter.

Icon _getCorrectIcon() {
    switch (iconName) {
      case 'name-a':
        return Icon(Icons.a);
      case 'name-b':
        return Icon(Icons.b);
      case 'name-c':
        return Icon(Icons.c);
      default:
        return Icon(Icons.a);
    }
  }

replace your Row to:

Row(
      mainAxisAlignment: MainAxisAlignment.start,
      children: <Widget>[
        _getCorrectIcon(),
        SizedBox(
          width: 15,
        ),
        Text("RaisedButton",
            style: TextStyle(color: Colors.white, fontSize: 14)),
      ],
    ),