After upgrade Flutter 3.3.0 RaisedButton showing error: The method 'FlatButton' isn't defined for the type 'CartScreen'. (undefined_method

Question

FlatButton(
  child: Text('ORDER NOW'),
  onPressed: () {
    Provider.of<Orders>(context, listen: false).addOrder(
      cart.items.values.toList(),
      cart.totalAmount,
    );
    cart.clear();
  },
  textcolor: Theme.of(context).primaryColor,

Answer 1

You can check breaking-changes/buttons

To have the same visual look

final ButtonStyle flatButtonStyle = TextButton.styleFrom(
  primary: Colors.black87,
  minimumSize: Size(88, 36),
  padding: EdgeInsets.symmetric(horizontal: 16.0),
  shape: const RoundedRectangleBorder(
    borderRadius: BorderRadius.all(Radius.circular(2.0)),
  ),
);

TextButton(
  style: flatButtonStyle,
  onPressed: () { },
  child: Text('Looks like a FlatButton'),
)

You can find more about restoring-the-original-button-visuals

Answer 2

https://docs.flutter.dev/development/tools/sdk/release-notes/release-notes-3.3.0

Remove deprecated RaisedButton by @Piinks in https://github.com/flutter/flutter/pull/98547