How to read data from firebase inside AlertDialog widget? - firebase

Question

I am trying to read data from firebase inside an AlertDialog in flutter, when a button is pressed, and then update it afterwards.
I have tried using a StreamBuilder, but nothing happens
new FlatButton(
child: const Text('+ Add'),
onPressed: () {
StreamBuilder(
stream: Firestore.instance.collection('users').document(user.uid).collection('Filtre').document('ChooseSelf').snapshots(),
builder: (context, snapshot) {
var TypeSelfFilters = snapshot.data;
List<String> ListOfTypeSelf = List.from(TypeSelfFilters["Personer"]);
ListOfTypeSelf.add("value of TextFormField");
Firestore.instance.collection('users').document(user.uid).collection('Filtre').document('ChooseSelf').updateData({'Personer': ListOfTypeSelf});
}
);
Navigator.pop(context);
}
);
I do not get any errors, but the code inside the StreamBuilder is not executed for some reason.
Thank You

Answer 1

Hm... It looks to me that you are expecting to get the data when the use taps on FlatButton.
Let's look what happens:
tap on FlatButton
Instantiate a StreamBuilder
Start getting data from Firestore
Do some Firestore magic, update date
Then close dialog by navigator.pop()
Problem: you call navigator.pop() right after Instantiation of StreamBuilder. StreamBuilder has to wait somewhat to get the data. If you pop a route, and with that destroying your alert dialog, the builder callback will not be called. So the actual sequence of things happening is: Tap -> Instantiate StreamBuilder -> pop route
Recommendation: why wrap your computation in a StreamBuilder? You could do:
onPressed: () {
Firestore.instance.collection('users')/*...*/.snapshots().then((snapshot) async {
// then branch is executed once snapshot is retrieved from firestore
var TypeSelfFilters = snapshot.data;
// do some more computation and magic
await Firestore.instance.collection/*...*/.updateData();
// wait for updateData to finish
Navigator.pop(context); // this context is not the context inside the StreamBuilder
});
}

Answer 2

Thanks to Daniel V. i found a solution:
var myData = Firestore.instance.collection('users').document(user.uid).collection('Filtre').document('ChooseSelf').snapshots().first;
myData.then((snapshot) async {
var TypeSelfFilters = snapshot.data;
List<String> ListOfTypeSelf = List.from(TypeSelfFilters["Personer"]);
ListOfTypeSelf.add("bare en test");
Firestore.instance.collection('users').document(user.uid).collection('Filtre').document('ChooseSelf').updateData({'Personer': ListOfTypeSelf});
Navigator.pop(context); // this context is not the context inside the StreamBuilder
});
}
)