check firestore has document or not using Future Builder - flutter

Question

Full code
class yourBookings extends StatefulWidget {
#override
_yourBookingsState createState() => _yourBookingsState();
}
class _yourBookingsState extends State<yourBookings> {
StateModel appState;
bool _loadingVisible = false;
#override
Widget build(BuildContext context) {
appState = StateWidget.of(context).state;
final number = appState?.user?.number ?? '';
Future getPosts() async {
var firestore = Firestore.instance;
QuerySnapshot qn = await firestore
.collection("confirmed_c_rides2")
.document(number)
.collection("1")
.getDocuments();
return qn.documents;
}
return Scaffold(
appBar: AppBar(
title: Text("Your Bookings :"),
),
body: Container(
child: FutureBuilder(
future: getPosts(),
builder: (_, snapshot) {
if (snapshot.connectionState == ConnectionState.waiting) {
return Center(
child: Text("Loading ..."),
);
} else if (snapshot.hasData) {
return ListView.builder(
itemCount: snapshot.data.length,
itemBuilder: (_, index) {
Widget image_carousel = new Container(
height: 200.0,
child: new Carousel(
//borderRadius: BorderRadius.all(Radius.circular(2.0)),
boxFit: BoxFit.fitHeight,
images: [
Image.network(
"${snapshot.data[index].data["driverImage"]}"),
Image.network(
"${snapshot.data[index].data["carImage"]}")
],
autoplay: true,
animationCurve: Curves.fastOutSlowIn,
animationDuration: Duration(milliseconds: 1000),
dotSize: 4.0,
indicatorBgPadding: 6.0,
dotBgColor: Colors.transparent,
),
);
return Card(
child: ListTile(
title: Column(
children: <Widget>[
SizedBox(height: 10),
Text(
"Status: ${snapshot.data[index].data["status"]}",
style: TextStyle(fontWeight: FontWeight.bold),
),
SizedBox(height: 10),
image_carousel,
Text(
"Name: ${snapshot.data[index].data["driverName"]}"),
SizedBox(height: 10),
Text(
"Gender: ${snapshot.data[index].data["gender"]}"),
SizedBox(height: 10),
Text(
"Experience: ${snapshot.data[index].data["experience"]}"),
SizedBox(height: 10),
Text(
"Number: ${snapshot.data[index].data["driverNumber"]}"),
SizedBox(height: 10),
Text(
"Time: ${snapshot.data[index].data["time"]}"),
SizedBox(height: 10),
Text(
"Scheduled on: ${snapshot.data[index].data["rideOn"]}"),
SizedBox(height: 10),
RaisedButton(
color: Colors.black,
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (_) => new issue()));
},
child: Text(
"Having issue",
style: TextStyle(color: Colors.white),
),
),
SizedBox(height: 10),
RaisedButton(
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (_) => rating1()));
},
child: Text("Rate driver"),
)
],
),
),
);
});
} else if (snapshot==null) {
return Center(
child: Text("not found..."),
);
}
return Center(
child: Text("not found 2..."),
);
}),
),
);
}
}
getPosts() refers to the firestore location for fetching data.
I want to check whether firestore contains number or not as a document using Future Builder.How can i do that?
number -> 1 contains further details.
If number does not exists then show data from firestore else show "not found...".How can i do that?
Future builder is used to stream firestore.