The data from my firestore isn't displayed - flutter

Question

I tried to build an application, which shows the user some places on a google maps. The data for the places (location, name) should the app take from the firestore. The app already can display the maker in the google maps, but I also want some details in the bottom of the application in an Animated Builder, but it doesn't work. The problem is, that I can't get the name of the place with specify['name'] in my _restaurantList function, but in the initMarker function it works. I think it has to do something with the _restaurantList(specify) and the return _restaurantList(index) but I don't know what the mistake is. I also tried to use specify instead of index in the _restaurantList(index), but then I got an error. But I think I have to use _restaurantList(specify) in order to use specify['name'] afterwards.
Does anyone know what my mistake is?
That's my code:
void initMarker(specify, specifyId) async {
// await Firebase.initializeApp();
var markerIdVal = specifyId;
final MarkerId markerId = MarkerId(markerIdVal);
final Marker marker = Marker(
markerId: markerId,
position:
LatLng(specify['location'].latitude, specify['location'].longitude),
infoWindow: InfoWindow(title: specify['name'], snippet: 'Shop'),
);
print(specify['location'].latitude);
nameTest = specify['name'];
setState(() {
markers[markerId] = marker;
print(markerId.toString() + '__________________________');
});
}
getMarkerData() async {
Firestore.instance.collection('seller').getDocuments().then((myMockDoc) {
if (myMockDoc.documents.isNotEmpty) {
for (int i = 0; i < myMockDoc.documents.length; i++) {
length = myMockDoc.documents.length;
print(length);
initMarker(
myMockDoc.documents[i].data(), myMockDoc.documents[i].documentID);
}
}
});
}
_restaurantList(specify) {
return AnimatedBuilder(
animation: _pageController,
builder: (BuildContext context, Widget widget) {
double value = 1;
if (_pageController.position.haveDimensions) {
//value = _pageController.page - index;
value = (1 - (value.abs() * 0.3) + 0.06).clamp(0.0, 1.0);
}
return Center(
child: SizedBox(
height: Curves.easeInOut.transform(value) * 175.0,
width: Curves.easeInOut.transform(value) * 350.0,
child: widget,
),
);
},
child: InkWell(
onTap: () {
null;
},
child: Stack(
children: [
Center(
child: Container(
margin: EdgeInsets.symmetric(
horizontal: 10.0,
vertical: 20.0,
),
height: 125.0,
width: 275.0,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(10.0),
boxShadow: [
BoxShadow(
color: Colors.black54,
offset: Offset(0.0, 4.0),
blurRadius: 10.0,
),
]),
child: Container(
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(10.0),
color: Colors.white),
child: Text(
specify['name'],
),
),
),
)
],
),
),
);
}
And this is in the Scaffold:
Positioned(
bottom: 20.0,
child: Container(
height: 200.0,
width: MediaQuery.of(context).size.width,
child: PageView.builder(
controller: _pageController,
itemCount: length,
itemBuilder: (BuildContext context, int index) {
return _restaurantList(index);
},
),
),
)