Flutter: StreamBuilder called 3 times - firebase

Question

i have a StreamBuilder,
the stream is from firebase (cloud firestore),
when I print this
print(!snapshot.hasData);
I got these results (3 times),
true
false
true...
please note: on the firestore i have some documents,
and when i open this page on my app it shows the document for one second then disappears, i do not know why ?
my code is here
import 'package:Tawseelat/ReadyToUse/DataBase.dart';
import 'package:Tawseelat/ReadyToUse/NavigationBarForUser.dart';
import 'package:Tawseelat/ReadyToUse/Whatsapp.dart';
import 'package:Tawseelat/ReadyToUse/constants.dart';
import 'package:flutter/material.dart';
import 'package:get/get.dart';
class TakenOrder extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(
'توصيلات',
style: TextStyle(fontWeight: FontWeight.bold),
),
),
body: StreamBuilder(
stream: DataBase().takenOrder,
builder: (context, snapshot) {
print(!snapshot.hasData);
if (!snapshot.hasData || snapshot.data.documents.length == 0) {
return Center(child: Text('لا توجد طلبات حاليا'));
} else {
return ListView.builder(
itemCount: snapshot.data.documents.length ?? 0,
itemBuilder: (context, index) {
var data = snapshot.data.documents[index];
return SingleChildScrollView(
child: Card(
child: Column(
children: [
Text(
'لقد قمت بقبول هذا الطلب',
),
Divider(),
Directionality(
textDirection: TextDirection.rtl,
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: [
Text(
'من',
style: TextStyle(
color: kPrimaryColor,
fontWeight: FontWeight.bold),
),
Text(
'الى',
style: TextStyle(
color: kPrimaryColor,
fontWeight: FontWeight.bold),
),
],
),
),
Directionality(
textDirection: TextDirection.rtl,
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: [
Text(
'${data['fromAlmohafda']} ( ${data['fromAlmntaqa']} )'),
Text(
'${data['toAlmohafda']} ( ${data['toAlmntaqa']} )'),
],
),
),
Divider(),
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
FlatButton.icon(
onPressed: () {
//TODO for Done
DataBase().orderComplate(data.id);
},
icon: Icon(
Icons.done_all,
color: kPrimaryColor,
),
label: Get.width < 300
? Text('تم التسليم')
: Container()),
FlatButton.icon(
onPressed: () {
Whatsapp().launchURL(data['posterNo']);
},
icon: Icon(
Icons.message,
color: kPrimaryColor,
),
label: Text('لتواصل')),
FlatButton.icon(
onPressed: () {},
icon: Icon(
Icons.attach_money,
color: Colors.green,
),
label: Text('${data['price']} OMR')),
],
),
],
),
));
},
);
}
},
),
bottomNavigationBar: MyNavigationBarForUser(),
);
}
}