Is it okay to extend some class and use it in build()? - flutter

Question

I have a widget that presents an error to a user. I want to have it in two variations:
the first would be a page element to show the error right in the view, replacing some portion of content
the second would be presented to a user as a dialog window.
For the second one I want to tweak the layout a little bit and use Dialog as a wrapped. So I created a separate widget, who extends my current one so I can skip adding duplicate fields in class.
class ConnectionErrorDialog extends ConnectionErrorWidget {
ConnectionErrorDialog(
{required String errorText,
required VoidCallback mainButtonOnTap,
String mainButtonText = 'Понятно'})
: super(
errorText: errorText,
mainButtonText: mainButtonText,
mainButtonOnTap: mainButtonOnTap);
#override
Widget build(BuildContext context) {
return Dialog(
elevation: 24.0,
child: Padding(
padding: EdgeInsets.all(20.0),
child: ConnectionErrorWidget(
errorText: errorText,
mainButtonOnTap: mainButtonOnTap,
mainButtonText: mainButtonText,
),
));
}
}
class ConnectionErrorWidget extends StatelessWidget {
ConnectionErrorWidget({
required this.errorText,
required this.mainButtonOnTap,
this.mainButtonText = 'Попробовать снова',
});
final String errorText;
final String mainButtonText;
final VoidCallback mainButtonOnTap;
#override
Widget build(BuildContext context) {
return UserErrorWidget(
errorText: errorText,
mainButtonText: mainButtonText,
mainButtonOnTap: mainButtonOnTap,
showAsDialog: false);
}
}
I want to understand, is it even okay to extend some class and use it in build()? Maybe there's other, better way to achieve the same result?

Answer 1

You can extend widgets like that, but the only benefit is omitting fields duplication. But it looks like you can do something like that:
class ConnectionErrorWidget extends StatelessWidget {
const ConnectionErrorWidget({
#required this.errorText,
#required this.mainButtonOnTap,
this.mainButtonText,
this.showAsDialog = false,
});
final bool showAsDialog;
final String errorText;
final String mainButtonText;
final VoidCallback mainButtonOnTap;
#override
Widget build(BuildContext context) {
if (showAsDialog) {
return Dialog(
elevation: 24.0,
child: Padding(
padding: const EdgeInsets.all(20.0),
child: _buildUserError(),
));
}
return _buildUserError();
}
Widget _buildUserError() {
return UserErrorWidget(
errorText: errorText,
mainButtonText: mainButtonText ?? (showAsDialog ? 'Попробовать снова' : 'Понятно'),
mainButtonOnTap: mainButtonOnTap,
showAsDialog: showAsDialog);
}
}
In that case, besides omitting fields duplication, your benefit is constructor arguments omitting.
I think that there is not much difference between these variants and you can use any variant you like more.