Use Futurebuilder to create a DropdownFormField Flutter? - flutter

Question

I'm new to flutter and have a array in firestore. It's structure is:
Now i want to fetch that array, and use that array to build a dropdownFormfield.
My fetch Function is following:
fetchSchoolList() async {
List<dynamic> data = [];
Future<DocumentSnapshot<Object?>> result = schoolList.doc('List').get();
return result;
}
and my FutureBuilder is:
FutureBuilder<DocumentSnapshot<Object?>>(
future: fetchSchoolList(),
builder: (BuildContext context,
AsyncSnapshot<DocumentSnapshot> snapshot) {
if (snapshot.connectionState ==
ConnectionState.active) {
return CircularProgressIndicator();
}
if (snapshot.hasError) {
return Text("Something went wrong");
}
if (snapshot.connectionState == ConnectionState.done) {
print(snapshot);
}
return Text('Loading List');
}),
But with this i'm even unable to get that array to print. I am getting error:
type 'Future' is not a subtype of type 'Future<DocumentSnapshot<Object?>>?'
Please help, i'm stuck here for days.#

Answer 1

There's a couple of things you could do:
First of all change fetchSchoolList() async {...} to something like this:
Future<DocumentSnapshot<List<String>?>>() async {
Future<DocumentSnapshot<List<String>?>> result =schoolList.doc('List').get();
return result;
}
Object isn't exactly a type, also flutter doesn't really know how to store information in with the type <Object>. Also you don't reference the data variable anywhere so it has been omitted.
Next change your FutureBuilder to something like this:
FutureBuilder<DocumentSnapshot<List<String>?>>(
future: fetchSchoolList(),
builder: (context, snapshot) {
if (snapshot.connectionState ==
ConnectionState.active) {
return CircularProgressIndicator();
}
if (snapshot.hasError) {
return Text("Something went wrong");
}
if (snapshot.connectionState == ConnectionState.done) {
print(snapshot);
}
return Text('Loading List');
}),
This will specify what is being returned by the future (Basically the FutureBuilder's type) and because of that, you do not need to specify the snapshot type.