Why GridView.builder clear when obtain more data in flutter - flutter

Question

I have my GRidView builder and I have my future and my ScrollController, why my gridView clear when scrollController is equal than mi maxScroll and obtain more information? It's supposed to show all of it, not the latest information.
this is my code
future: _future ,
builder: (BuildContext context, AsyncSnapshot snapshot) {
if(snapshot.hasData){
List<dynamic> loaded = snapshot.data;
return
Container(
width: double.infinity,
height: _screenSize.height * .8,
child: GridView.builder(
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 3,
childAspectRatio: MediaQuery.of(context).size.width /(MediaQuery.of(context).size.height /1.5),),
controller: _controller,
itemCount: loaded.length,
itemBuilder: (context, i){
return _row(context,loaded,i);
},
)
);
}else{
and the constructor
Future<List> _future;
ScrollController _controller = ScrollController(initialScrollOffset: 0.0, keepScrollOffset: true);
_SearchPageState(){
_controller.addListener(() {
if(_controller.position.pixels >= _controller.position.maxScrollExtent-30 ){
setState(() {
_future = videoJuegos.getPaginationPopular();
});
}
});
_future = videoJuegos.getPaginationPopular();
}

Answer 1

Your Gridview.builder is clearing because of this line:
List<dynamic> loaded = snapshot.data;
It will clear the current list and add the new data. You should use initialize your list above the future and then use list.add:
List<dynamic> loaded = [];
future: _future ,
builder: (BuildContext context, AsyncSnapshot snapshot) {
if(snapshot.hasData){
loaded.add(snapshot.data);
return
Container(
width: double.infinity,
height: _screenSize.height * .8,
child: GridView.builder(
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 3,
childAspectRatio: MediaQuery.of(context).size.width /(MediaQuery.of(context).size.height /1.5),),
controller: _controller,
itemCount: loaded.length,
itemBuilder: (context, i){
return _row(context,loaded,i);
},
)
);
}else{
Hope that helps.