How to fix Instance of Future<int> in appbar title in Flutter? - flutter

Question

I would like the appBar title of my Scaffold to display the total number of items (length) in a Firebase Query at launch, but it keeps returning Instance of 'Future<int>'. How can I fix this?
Here's my code:
Query itemList = FirebaseFirestore.instance
.collection('simple');
Future<int> itemCount() async => FirebaseFirestore.instance
.collection('simple')
.snapshots()
.length;
...
return Scaffold(
appBar: AppBar(
title: Text("# Items: " + itemCount().toString()),
// DISPLAYS: # Items: Instance of 'Future<int>'
Unfortunately, it displays Instance of 'Future<int>'. What do I have to change to obtain the item count (length) and have that show-up in the title text?
Thank you!

Answer 1

You can use a FutureBuilder like this :
AppBar(
title: FutureBuilder<String>(
future: itemCount(),
builder: (BuildContext context, AsyncSnapshot<int> snapshot) {
if (snapshot.hasData) {
return Text("# Items: " + snapshot.data.toString());
}else {
Text("No data");
}
}),
)

Answer 2

You are calling a "Future" function, thats the function return a Future so you cant display it like that, you need to use an await (if you are in async function) or a .then() (if you'r not in async function).
The best way to print it in your case is to use a FutureBuilder or the keyword await.

Answer 3

After some experimenting, I came to the conclusion that I need to use StreamBuilder. Here's the solution that fixed it:
appBar: AppBar(
title: StreamBuilder(
stream: itemList.snapshots(),
builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
if (snapshot.connectionState == ConnectionState.waiting) {
return const Text("# Items: ...");
}
else if (snapshot.hasData) {
return Text("# Items: ${snapshot.data?.docs.length ?? 0}");
}
else {
return const Text('# Items: 0');
}
}, // Item Builder
), // Stream Builder
), // App Bar
Screenshot of completed project with # Items in appBar title:
The floating action button adds items to the list and onTap deletes the selected item from the list. The title remains updated.
I hope this helps someone in the future.