Flutter - How can I save the selected index of DropDownMenu to FireStore when the form is submitted - firebase

Question

Here is my code for the dropdown list
Container(
decoration: BoxDecoration(
color: Colors.lightBlueAccent,
//border: ,
borderRadius: BorderRadius.circular(20),
),
//color: Colors.white,
margin:
EdgeInsets.only(left: 50, right: 50),
child: StreamBuilder<QuerySnapshot>(
stream: Firestore.instance
.collection("Choose Platform")
.snapshots(),
builder: (context, snapshot) {
if (!snapshot.hasData)
const Text("Loading.....");
else {
List<DropdownMenuItem>
chooseplatform = [];
for (int i = 0;
i <
snapshot.data.documents
.length;
i++) {
DocumentSnapshot snap =
snapshot.data.documents[i];
chooseplatform.add(
DropdownMenuItem(
child: Text(
snap.documentID,
style: TextStyle(
color: Colors.black),
),
value: "${snap.documentID}",
),
);
}
return Row(
mainAxisAlignment:
MainAxisAlignment.center,
children: <Widget>[
DropdownButton(
items: chooseplatform,
onChanged:
(choosingplatform) {
final snackBar = SnackBar(
content: Text(
'Selected Platform is $choosingplatform',
style: TextStyle(
color: Color(
0xff1ffcb7)),
),
);
Scaffold.of(context)
.showSnackBar(
snackBar);
setState(() {
chosenPlatform =
choosingplatform;
});
},
value: chosenPlatform,
isExpanded: false,
hint: new Text(
"Choose Platform",
style: TextStyle(
color: Colors.black),
),
),
],
);
}
})),
And this is the code for the Raised button
RaisedButton(
padding:
EdgeInsets.only(left: 10, right: 10),
onPressed: () async {
Firestore.instance.runTransaction(
(Transaction transaction) async {
final CollectionReference reference =
Firestore.instance
.collection('Tournaments');
await reference
.document('Fifa Tournaments')
.collection('Fifa Tourneys')
.add({
'tourneyname':
tourneynameController.text,
'tourneygame':
tourneydateController.text,
});
tourneynameController.clear();
tourneydateController.clear();
});
Navigator.of(context).pop();
},
child: Text(
'Create Tournament',
style: TextStyle(fontSize: 16),
),
color: const Color(0xff1ffcb7),
textColor: Colors.white,
shape: RoundedRectangleBorder(
borderRadius:
BorderRadius.circular(18.0),
side: BorderSide(color: Colors.white),
),
),
Right now, I can only save the values for my TextFormFields and not the Drop down list.
In a nutshell, what i'm doing right now is retrieving values from a collection and displaying them in a dropdownmenu, but what i want to do is retrieve the values then save the selected value in another collection called 'Fifa tourneys' when the form is submitted.
Thanks!

Answer 1

Solved!
All i had to do was save the variable for the the selectedIndex to my firestore collection.
onPressed: () async {
Firestore.instance.runTransaction(
(Transaction transaction) async {
final CollectionReference reference =
Firestore.instance
.collection('Tournaments');
await reference
.document('Fifa Tournaments')
.collection('Fifa Tourneys')
.add({
'tourneyname':
tourneynameController.text,
'tourneygame':
tourneydateController.text,
'tourneyplatform': chosenPlatform,// this is the one
});
tourneynameController.clear();
tourneydateController.clear();
chosenPlatform.clear();
});
Navigator.of(context).pop();
},