How to change button color based on callback in flutter

Question

I'm trying to change a button colour based on firebase text. When a user presses on the container then a callback will check a condition if the button match with the firebase instance then the button colour will be green if not then red.

Like this one

class TestBtnWidget extends StatefulWidget {
  const TestBtnWidget({
    Key? key,
    this.btnText,
    this.customAction,
    this.colorChange,
  }) : super(key: key);

  final String? btnText;
  final Future<dynamic> Function()? customAction;
  final Color? colorChange;

  @override
  _TestBtnWidgetState createState() => _TestBtnWidgetState();
}

class _TestBtnWidgetState extends State<TestBtnWidget> {
  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) => setState(() {}));
  }

  @override
  Widget build(BuildContext context) {
    return Align(
      alignment: AlignmentDirectional(0, 0),
      child: InkWell(
        onTap: () async {
          await widget.customAction?.call();
        },
        child: Container(
          width: 180,
          height: 50,
          decoration: BoxDecoration(
            color: widget.colorChange,
            borderRadius: BorderRadius.circular(6),
          ),
          alignment: AlignmentDirectional(0, 0),
          child: Text(
            widget.btnText!,
            style: Theme.of(context).bodyText1,
          ),
        ),
      ),
    );
  }
}

Answer 1

check your response and if your status request was 200, means you got that clearly and after that change the color with setState((){})

Answer 2

First thing first, I would totally avoid magic instructions like these:

    WidgetsBinding.instance.addPostFrameCallback((_) => setState(() {}));

Just get rid of this and if you got problems please let us know what's going on in another question.

Second, this problem may be suited for Riverpod . First, create a provider that listen holds whatever state you get from firestore:

final firstRequestProvider = StateProvider<bool>((ref) => false);
final myColorRequestProvider = FutureProvider<Color>((ref) {
  final isFirstRequest = ref.watch(firstRequestProvider);
  if (isFirstRequest) return Colors.white;

  final response = await ... // RESTful or by using the Firestore SDK
  
  return Color.from(response.body);
});

Then in your Widget you'll have something like:

class YourWidget extends ConsumerWidget {
  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final color = ref.watch(myColorRequestProvider).maybeWhen(
       data: (color) => color,
       orElse: Colors.white
    );
    
    return ElevatedButton(
      onTap: () {
        ref.read(firstRequestProvider.notifier).state = false;
        ref.refresh(myColorRequestProvider);
      },
      // Style in which you'll need to add the color
      child:  // ... some text or whatever
    );
  }
}

This is just some random ideas with Riverpod, take this with a grain of salt. The takeaway here is: when you need to implement something, try to follow some known patterns that let you write reliable code. Good luck!