Using Flutter Checkbox() and obtaining initial value from Firestore - flutter

Question

I'm no experienced programmer and I could find no guidance, hence this question. I have a working solution but not sure if this is good practice.
I am using the widget Checkbox() in a Form(). Widgets like TextFormField() and DateTimeField() have a parameter called 'initialValue'. Checkbox() does not.
For TextFormField() and DateTimeField() I obtained the initialValue by:
#override
Widget build(BuildContext context) {
final user = Provider.of<User>(context);
return StreamBuilder<UnitDetails>(
stream: DatabaseServices(uid: user.userUid, unitUid: widget.unitUid)
.unitByDocumentID,
builder: (context, unitDetails) {
if (!unitDetails.hasData) return Loading();
return Scaffold(
etc
The Checkbox(value: residentialUnit,) can not have its initial value set inside the builder:. The parameter 'value:' needs to be set true or false before the builder: ie before the value is obtained from Firestore! The way I solved this is by using initState(). An extra call to Firestore and more code for this one input widget.
#override
void initState() {
super.initState();
Firestore.instance
.collection("units")
.document(widget.unitUid)
.snapshots()
.listen((snapshot) {
residentialUnit = snapshot.data['unitResidential'];
});
}
Is there a better way?

Answer 1

I think you can solve your problem with the following answer (using FormField).
Checkbox form validation
Following is a sample code.
FormField(
initialValue: userProfile.agreement,
builder: (state) {
return Column(
children: [
Row(
children: [
Checkbox(
activeColor: Colors.blue,
value: state.value,
onChanged:(value) {
setState(() {
state.didChange(value);
});
}
),
Expanded(child: Text('Sample checkbox')),
],
),
Text(
state.errorText ?? '',
style: TextStyle(
color: Theme.of(context).errorColor,
),
)
],
);
},
validator: (val) {
print('VAL: $val');
if (!val) {
return 'You need to accept terms';
} else {
return null;
}
},
)