Flutter add item to list
I will try to give an explanation of what is happing here take a look on this code:
import 'dart:async';
void main() {
List<int> userSearchItems = [];
Timer _sendTimeOutTimer;
const oneSec = Duration(seconds: 2);
_sendTimeOutTimer = Timer.periodic(oneSec, (Timer t) {
userSearchItems.add(1);
print(userSearchItems.length); // result 1 and it will be executed after 2 seconds
_sendTimeOutTimer.cancel();
});
print(userSearchItems.length); // result 0 and it will be executed first
}
The print inside asynchronous action(Timer) it will be executed after 2 seconds means after the asynchronous action ends but the one which is outside of asynchronous action(Timer) it will be executed directly without waiting 2 seconds, in your case the asynchronous action is listening to data .listen((data) =>
, so if you print the length outside of your asynchronous action you will not see the deferent because the item is not added yet.
Solution: you can create function witch return Future
and then wait until it's finished then print the length.
List<UserSearchItem> userSearchItems = [];
Future<String> submitAll() async {
Firestore.instance
.collection('insta_users')
.snapshots()
.listen((data) =>
data.documents.forEach((doc){
print(data.documents.length);
User user = new User.fromDocument(doc);
UserSearchItem searchItem = new UserSearchItem(user);
userSearchItems.add(searchItem);
print(user.bio);
return 'success';
}));
}
void yourFunction() async{
await submitAll();
print("Loaded");
print(userSearchItems.length);
}
Then call yourFunction()
.
Try to add print(userSearchItems.length);
inside forEach after adding the item and you will see the real length.