Change textfield value with firebase realtime database value - flutter

Question

I want to change two textfields value via firebase realtime database value in Flutter not sure how to do it
this is my code I am using Getx controller that is why a little confused
i am a beginner so ignore bad code
for Firebase :
static void readData() async
{
DatabaseReference dataRef = FirebaseDatabase.instance
.ref()
.child("test");
dataRef.once().then((snap)
{
if(snap.snapshot.value != null)
{
dataModelInfo = DataModel.fromSnapshot(snap.snapshot);
BlockController().fheight = dataModelInfo!.height.toString();
BlockController().flength = dataModelInfo!.length.toString();
print("height ="+ dataModelInfo!.height.toString());
print("length ="+ dataModelInfo!.length.toString());
}
});
}
For Textfields :
class BlockController extends GetxController{
final WallheightController = TextEditingController();
final WalllengthController = TextEditingController();
}
want to update text field data after retrieving from firebase
class SidesField extends StatelessWidget {
SidesField({
Key? key,
required this.labelText,
required this.controller, required Map Function(dynamic text) onChanged,
}) : super(key: key);
final String labelText;
final TextEditingController controller;
#override
Widget build(BuildContext context) {
return Padding(
padding: const EdgeInsets.all(8.0),
child: TextFormField(
keyboardType: const TextInputType.numberWithOptions(decimal: true),
controller: controller,
decoration: InputDecoration(
labelText: labelText,
labelStyle: const TextStyle(color: kPurpleColor),
enabledBorder: OutlineInputBorder(
borderRadius: BorderRadius.circular(10),
borderSide: const BorderSide(
color: kPurpleColor,
width: 3,
),
),
focusedBorder: OutlineInputBorder(
borderRadius: BorderRadius.circular(10),
borderSide: const BorderSide(
color: Colors.grey,
),
),
),
validator:(value){
if(value!.isEmpty){
return "Enter This Field";
}
return null;
},
),
);
}
}
Please tell my how to change value of text field after taking data from firebase realtime database