Get data from firebase using streambuilder - dart

I tried to get data from firebase but the function didn't work when i initialize it in initState.
and i tried to give it debugprint, it doesn't show in the terminal and there is no error or warning when i run the app.
void _getMarker() {
StreamBuilder(
stream: Firestore.instance
.collection('contentislamis')
.where('kategori', isEqualTo: 'Landmark')
.snapshots(),
builder: (context, snapshot) {
if (!snapshot.hasData) {
return Center(
child: CircularProgressIndicator(
valueColor: AlwaysStoppedAnimation<Color>(Colors.green)));
} else {
for (int i = 0; i < snapshot.data.documents.length; i++) {
_addMarkers(snapshot.data.documents[i]);
print("${snapshot.data.documents.length} markers added");
}
}
});
}
and this is the function to show the marker
void _addMarkers(DocumentSnapshot markData) {
final String markerIdVal = markData.documentID.toString();
final MarkerId markerId = MarkerId(markerIdVal);
double lat = double.tryParse(markData['posLat'].toString());
double long = double.tryParse(markData['posLong'].toString());
final Marker marker = Marker(
markerId: markerId,
position: LatLng(
lat,
long,
),
infoWindow: InfoWindow(
title: markData['judul'].toString(),
snippet: markData['posLat'] + markData['posLong']
),
icon: BitmapDescriptor.defaultMarkerWithHue(BitmapDescriptor.hueRed)
);
setState(() {
markers[markerId] = marker;
});
}

You need to add the key of the data you want to get from firestore
for eg:
// title is the key in the firestore documents, you need to add your key here
addMarkers(snapshot.data.documents[i].data["title"])
Following code should help you, in this example i am getting the data from cloud firestore and displaying it in Listview :
Code:
#override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
child: StreamBuilder<QuerySnapshot>(
stream: Firestore.instance.collection("posts").snapshots(),
builder:
(BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
if (snapshot.hasError) {
return new Text('Error: ${snapshot.error}');
}
if (snapshot.connectionState == ConnectionState.waiting) {
return Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Text("Loading..."),
SizedBox(
height: 50.0,
),
CircularProgressIndicator()
],
),
);
} else {
return ListView.builder(
itemCount: snapshot.data.documents.length,
itemBuilder: (_, index) {
return Card(
child: ListTile(
title: Text(
snapshot.data.documents[index].data["title"]), // getting the data from firestore
),
);
},
);
}
},
),
),
);
}

Related

Flutter - setState not updating a List inside a ListView.separated

I am saving a list of favorites in my game app, I can add or remove games from the list, but on the removeFavorite method, when I use setState in "games.remove(index)" the listview.separeted doesn't update. If close and open favorite screen, the list is updated but while I am at the favorite screen it doesn't update.
class _FavoriteScreenState extends State<FavoriteScreen> {
List<dynamic> favoriteList = [];
List<Game> games = [];
#override
void initState() {
loadFavorites();
super.initState();
}
#override
Widget build(BuildContext context) {
Widget _buildListView(Game game, int index){
return InkWell(
child: Container(
height: 80,
child: Row(
children: <Widget>[
Expanded(
flex: 1,
child: Container(
margin: EdgeInsets.only(left: 5),
child: Image.network(game.cover),
),
),
Expanded(
flex: 2,
child: Container(
child: Row(
children: <Widget>[
SizedBox(width: 15,),
Text(
game.title,
overflow: TextOverflow.ellipsis,
style: TextStyle(
color: Colors.white,
fontWeight: FontWeight.w300,
fontSize: 14
),
),
],
),
),
)
],
),
),
onLongPress: (){
_showDialog(index);
},
);
}
return Scaffold(
backgroundColor: Theme.of(context).backgroundColor,
appBar: AppBar(
title: Text("Favorites"),
),
body: Container(
margin: EdgeInsets.fromLTRB(16, 16, 16, screenHeight > 720 ? 90 : 62),
child: ListView.separated(
separatorBuilder: (BuildContext context, int index) => Divider(color: Colors.black,),
itemCount: games.length,
itemBuilder: (context, index){
return _buildListView(games[index], index);
},
)
),
);
}
Future<File> getFile() async{
final directory = await getApplicationDocumentsDirectory();
return File("${directory.path}/favorites.json");
}
Future<String> readFavorite() async{
try{
// Le e retorna o arquivo como String
final file = await getFile();
return file.readAsString();
} catch (e){
return null;
}
}
void loadFavorites() {
readFavorite().then((data){
// Transforma o arquivo JSON numa List
favoriteList = json.decode(data);
if(favoriteList.length > 0 && favoriteList != null){
favoriteList.forEach((map){
Game game = Game(map["cover"], map["title"], map["description"], map["url"]);
setState(() {
games.add(game);
});
});
} else {
}
print(games.length);
});
}
Future<File> saveFile() async{
String data = json.encode(favoriteList);
final file = await getFile();
return file.writeAsString(data);
}
void _showDialog(int index){
showDialog(
context: context,
builder: (BuildContext context){
return AlertDialog(
content: Text("?",
style: TextStyle(fontSize: 18) ,),
actions: <Widget>[
FlatButton(
child: Text("YES"),
onPressed: (){
Navigator.of(context).pop();
removeFavorite(index);
}
),
FlatButton(
child: Text("NO"),
onPressed: (){
Navigator.of(context).pop();
}
),
],
);
}
);
}
void removeFavorite(int index){
favoriteList.forEach((m) {
Map<String, dynamic> map = m;
if (map.containsValue(games[index].title)) {
favoriteList.remove(m);
saveFile();
setState(() {
games.remove(index);
});
}
});
}
}
My bad, I replaced the remove with removeAt and it worked.
setState(() {
games.removeAt(index);
});

Stream is not re-rendering when switching tabs on flutter

I have a stream builder that shows a list of "posts" from a server. I have used the BLoC architecture to accomplish this. But for some reason when I switch tabs and back the posts disappear how can I keep the posts from disappearing or have them re-render? Below is small part of my code I think is relevant I can add more if needed:
Tab UI (not all the code, file containing BLoC is imported at top):
#override
void initState() {
bloc.fetchMyPosts();
super.initState();
}
#override
Widget build(BuildContext context) {
return DefaultTabController(
length: 2,
child: Scaffold(
appBar: AppBar(
title: Text("Posts", style: Style.appBarStyle),
bottom: TabBar(
tabs: [
Tab(
text: "My Posts",
),
Tab(
text: "My Other Posts",
),
],
),
),
body: TabBarView(
children: [
Posts(stream: bloc.myPosts), //Stream builder with SliverChildBuilderDelegate
Posts(stream:bloc.myOtherPosts),//Stream builder with SliverChildBuilderDelegate
],
),
),
);
}
Stream Builder (Posts):
Widget Posts({Stream stream, //Other variables}) {
return StreamBuilder(
stream:stream,
builder: (BuildContext context, AsyncSnapshot snapshot) {
switch(snapshot.connectionState) {
case ConnectionState.none:
return Row(
children: <Widget>[
Flexible(
child: Text("Please check if you are connected to the internet"),
),
],
);
break;
case ConnectionState.waiting:
if (snapshot.data == null){
return Container(
color: Color(0xFFF4F4FF),
child: Container(child:Center(child:Text(variable?"Text one":"Text two"))));
} else return Column(
mainAxisSize: MainAxisSize.max,
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Center(
child: CircularProgressIndicator(),
),
Center(
child: Text("Loading"),
),
],
);
break;
case ConnectionState.active:
case ConnectionState.done:
if (snapshot.hasData) {
return Container(
color:Colors.white,
child: CustomScrollView(
scrollDirection: Axis.vertical,
shrinkWrap: false,
slivers: <Widget>[
SliverPadding(
padding: const EdgeInsets.symmetric(vertical: 24.0),
sliver: SliverList(
delegate: SliverChildBuilderDelegate(
(context, index) => PostCard(post:snapshot.data[index],//variables),
childCount: snapshot.data.length,
),
),
)
],
));
}
if (snapshot.data == null){
return Container(
color: Color(0xFFF4F4FF),
child: Container(child:Center(child:Text(variable?"Text one":"Text two"))));
}
}
});
}
BLoC:
class Bloc{
ApiClient _client = ApiClient();
final _myPosts = BehaviourSubject<List<Post>>();
final _myOtherPosts = BehaviourSubject<List<Post>>();
Stream<List<Post>> get myPosts => _myPosts.stream;
Stream<List<Post>> get myOtherPosts => _myOtherPosts.stream;
fetchMyPosts() async {
List<Post> posts = await _client.getMyPosts();
_myPosts.sink.add(posts);
}
fetchMyOtherPosts() async {
List<Post> posts = await _client.getMyOtherPosts();
_myOtherPosts.sink.add(posts);
}
dispose(){
_myPosts.close();
_myOtherPosts.close();
}
}
final bloc = Bloc();
Main Screen:
class MainScreen extends StatefulWidget {
UserBloc userBloc;
MainScreen({this.userBloc});
#override
_MainScreenState createState() => _MainScreenState();
}
class _MainScreenState extends State<MainScreen> {
int _currentIndex = 0;
onTabTapped(int index) {
setState(() {
_currentIndex = index;
});
}
Widget getPage(int index) {
if (index == 0) {
return PostPage(myHandle: widget.userBloc.userValue);
}
if (index == 1) {
return PageOne();
}
if (index == 3) {
return PageTwo();
}
if (index == 4) {
return PageThree(userBloc: widget.userBloc);
}
return PostPage(userBloc: widget.userBloc);
}
Widget customNav() {
return Container(
color: Colors.white,
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: <Widget>[
IconButton(
icon: Icon(Icons.library_books),
onPressed: () => setState(() {
_currentIndex = 0;
})),
// MORE ICONS but similar code
],
));
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Stack(children: <Widget>[
getPage(_currentIndex),
Positioned(
bottom: 0.0,
left: 0.0,
right: 0.0,
child: customNav(),
),
]));
}
}
Take a look at this code i put some comments. I can do this using streambuilder and bloc pattern simulating an async data fetching with future delayed. This widget is working but you will need adapt to your needs.
class TabWidget extends StatefulWidget {
#override
_TabWidgetState createState() => _TabWidgetState();
}
class _TabWidgetState extends State<TabWidget> with SingleTickerProviderStateMixin {
Bloc _bloc;
#override
void initState() {
super.initState();
_bloc = Bloc(); // can be your bloc.fetchData();
}
#override
void dispose() {
_bloc?.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) {
//i really recomment using stream builder to create all layout
// if length property is dynamic
return DefaultTabController(
length: 2,
child: Scaffold(
appBar: AppBar(
title: Text("Tab screen"),
bottom: TabBar(
tabs: [
Tab( text: "My Posts" ),
Tab( text: "Other" ),
],
),
),
body: StreamBuilder<List<Widget>>(
stream: _bloc.getTabData,
builder: (context, asyncSnapshot){
switch(asyncSnapshot.connectionState){
case ConnectionState.none:
return Row(
children: <Widget>[
Flexible(
child: Text("handle none state here, this is because i am simulate a async event"),
),
],
);
break;
case ConnectionState.waiting:
return Column(
mainAxisSize: MainAxisSize.max,
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Center(
child: CircularProgressIndicator(),
),
Center(
child: Text("Loading data..."),
),
],
);
break;
case ConnectionState.active:
case ConnectionState.done:
//assuming that snapshot has valid data...
return TabBarView(
children:[
asyncSnapshot.data[0],
asyncSnapshot.data[1],
],
);
}
}
),
),
);
}
}
class Bloc{
// post items
// just to simulate data
List<Widget> _tabList1 = List.generate(10, (index){ return Text("TAB 1 Item $index");} );
List<Widget> _tabList2 = List.generate(10, (index){ return Text("TAB 2 Item $index");} );
//tab's data stream
PublishSubject< List<Widget>> _tabData = PublishSubject();
Observable<List<Widget>> get getTabData => _tabData.stream;
Bloc() {
Future.delayed(Duration(seconds: 5), () {
List<Widget> tabDataWidgets = List();
// adding tab's data
tabDataWidgets.add( ListView(
children: _tabList1,
) );
tabDataWidgets.add( ListView(
children: _tabList2,
) );
_addingToSink( tabDataWidgets );
});
}
void _addingToSink( final List<Widget> list) => _tabData.sink.add( list );
dispose(){ _tabData?.close(); }
}
I changed PublishSubject to BehaviourSubject and it seemed to work. I used it in conjunction with Marcos Boaventura's answer as well. Although I used two stream builders.
PublishSubject: Starts empty and only emits new elements.
BehaviorSubject: It needs an initial value and replays it or the latest element to new subscribers.
I have fixed it another way like as I have take two Streem variable Example
final Stream<QuerySnapshot> showpost = FirebaseFirestore.instance
.collection("post")
.snapshots();
final Stream<QuerySnapshot> showpost2 = FirebaseFirestore.instance
.collection("post")
.snapshots();
And two-stream i have use two-variable ;

SliverAppbar remains visible when CustomScrollView with ScrollController is scrolled

Adding a ScrollController to function timelineList() causes the SliverAppBar to remain visible on scroll (when counter list is scrolled, SliverAppBar should hide). The issue goes away if the _scrollController is removed from the list (see timelineList function) but this gives rise to a new problem, I need to listen for when the scrollbar reaches bottom (to get more content).
See sample app below, copy/paste and run.
void main() => runApp(TestApp());
class TestApp extends StatelessWidget {
final _scrollController = new ScrollController();
TestApp(){
_scrollController.addListener(() {
if (_scrollController.position.pixels ==
_scrollController.position.maxScrollExtent) {
print('Get more data');
}
});
}
#override
Widget build(BuildContext context) {
TestBloc bloc = TestBloc();
bloc.fetchTestTimeline();
bloc.fetchTestAppBarTxt1();
bloc.fetchTestAppBarTxt2();
return MaterialApp(
home: new Scaffold(
backgroundColor: Colors.grey[200],
appBar: AppBar(
backgroundColor: Colors.blueGrey,
elevation: 0.0,
),
body: NestedScrollView(
headerSliverBuilder:
(BuildContext contrxt, bool innerBoxIsScrolled) {
return <Widget>[
buildSliverAppBar(context, bloc),
];
},
body: Column(
children: <Widget>[
timelineList(bloc),
],
)
)),
);
}
buildSliverAppBar(context, TestBloc bloc){
return SliverAppBar(
automaticallyImplyLeading: false,
backgroundColor: Colors.grey[400],
expandedHeight: 200.0,
floating: true,
snap: true,
flexibleSpace: FlexibleSpaceBar(
background: Column(
children: <Widget>[
Container(
padding: EdgeInsets.only(left: 2.0),
height: 200,
child: Column(
children: <Widget>[
StreamBuilder(
stream: bloc.testAppBarTxt1,
initialData: null,
builder: (BuildContext context,
AsyncSnapshot<String> snapshot) {
if (snapshot.data == null)
return buildProgressIndicator(true);
return Expanded(
child: Text('${snapshot.data}'));
}),
StreamBuilder(
stream: bloc.testAppBarTxt2,
initialData: null,
builder: (BuildContext context,
AsyncSnapshot<String> snapshot) {
if (snapshot.data == null)
return buildProgressIndicator(true);
return Expanded(
child: Text('${snapshot.data}'));
}),
],
),
)
],
),
));
}
timelineList(TestBloc bloc) {
return StreamBuilder(
stream: bloc.getTestTimeline,
initialData: null,
builder: (BuildContext context, AsyncSnapshot<List<int>> snapshot) {
if (snapshot.connectionState == ConnectionState.waiting) {
return Expanded(child: buildProgressIndicator(true));
}
List<int> val = snapshot.data;
if (val.isNotEmpty) {
addToTimelineList(val, bloc);
return Expanded(
child: CustomScrollView(
controller: _scrollController,
slivers: <Widget>[
SliverList(
delegate: SliverChildListDelegate(new List<Widget>.generate(bloc.listTest.length, (int index) {
if (index == bloc.listTest.length) {
return buildProgressIndicator(bloc.isPerformingRequest);
} else {
return bloc.listTest[index];
}
})
))
],
),
);
}
});
}
void addToTimelineList(List<int> list, TestBloc bloc) {
for (var val in list) {
bloc.listTest.add(Text('$val'));
}
}
}
Widget buildProgressIndicator(showIndicator) {
return new Padding(
padding: const EdgeInsets.all(8.0),
child: new Center(
child: new Opacity(
opacity: showIndicator ? 1.0 : 0.0,
child: Container(
width: 10.0,
height: 10.0,
child: new CircularProgressIndicator(
)),
),
),
);
}
class TestBloc {
String appbar1Val;
String appbar2Val;
List<Text> listTest = new List<Text>();
bool isPerformingRequest = false;
final _testAppBarText1 = BehaviorSubject<String>();
Observable<String> get testAppBarTxt1 => _testAppBarText1.stream;
final _testAppBarText2 = BehaviorSubject<String>();
Observable<String> get testAppBarTxt2 => _testAppBarText2.stream;
final _testTimeline = PublishSubject<List<int>>();
Observable<List<int>> get getTestTimeline => _testTimeline.stream;
fetchTestTimeline() async {
List item = await Future.delayed(
Duration(seconds: 2), () => List<int>.generate(100, (i) => i));
_testTimeline.sink.add(item);
}
fetchTestAppBarTxt1() async {
appbar1Val = await Future.delayed(Duration(seconds: 2), () => "Text One");
_testAppBarText1.sink.add(appbar1Val);
}
fetchTestAppBarTxt2() async {
appbar2Val = await Future.delayed(Duration(seconds: 2), () => "Text Two");
_testAppBarText2.sink.add(appbar2Val);
}
dispose() {
_testAppBarText1.close();
_testAppBarText2.close();
_testTimeline.close();
}
}
It's possible to achive the same result with wrapping your list with a Notification Listener.
NotificationListener<ScrollNotification>(
onNotification: (sn) {
if (sn.metrics.pixels ==
sn.metrics.maxScrollExtent) {
print('Get more data');
}
},
child: CustomScrollView(...
Edit: Since my initial answer didn't cover the animateTo use case, I got it working by removing the outer NestedScrollView. Here is the modified example.
void main() => runApp(TestApp());
class TestApp extends StatelessWidget {
final _scrollController = new ScrollController();
TestApp() {
_scrollController.addListener(() {
if (_scrollController.position.pixels ==
_scrollController.position.maxScrollExtent) {
print('Get more data');
}
});
}
#override
Widget build(BuildContext context) {
TestBloc bloc = TestBloc();
bloc.fetchTestTimeline();
bloc.fetchTestAppBarTxt1();
bloc.fetchTestAppBarTxt2();
return MaterialApp(
home: new Scaffold(
backgroundColor: Colors.grey[200],
appBar: AppBar(
backgroundColor: Colors.blueGrey,
elevation: 0.0,
),
body: Column(
children: <Widget>[
timelineList(bloc),
],
),
),
);
}
buildSliverAppBar(context, TestBloc bloc) {
return SliverAppBar(
automaticallyImplyLeading: false,
backgroundColor: Colors.grey[400],
expandedHeight: 200.0,
floating: true,
snap: true,
flexibleSpace: FlexibleSpaceBar(
background: Column(
children: <Widget>[
Container(
padding: EdgeInsets.only(left: 2.0),
height: 200,
child: Column(
children: <Widget>[
StreamBuilder(
stream: bloc.testAppBarTxt1,
initialData: null,
builder: (BuildContext context,
AsyncSnapshot<String> snapshot) {
if (snapshot.data == null)
return buildProgressIndicator(true);
return Expanded(child: Text('${snapshot.data}'));
}),
StreamBuilder(
stream: bloc.testAppBarTxt2,
initialData: null,
builder: (BuildContext context,
AsyncSnapshot<String> snapshot) {
if (snapshot.data == null)
return buildProgressIndicator(true);
return Expanded(child: Text('${snapshot.data}'));
}),
],
),
)
],
),
));
}
timelineList(TestBloc bloc) {
return StreamBuilder(
stream: bloc.getTestTimeline,
initialData: null,
builder: (BuildContext context, AsyncSnapshot<List<int>> snapshot) {
if (snapshot.connectionState == ConnectionState.waiting) {
return Expanded(child: buildProgressIndicator(true));
}
List<int> val = snapshot.data;
if (val.isNotEmpty) {
addToTimelineList(val, bloc);
return Expanded(
child: CustomScrollView(
controller: _scrollController,
slivers: <Widget>[
buildSliverAppBar(context, bloc),
SliverList(
delegate: SliverChildListDelegate(
new List<Widget>.generate(bloc.listTest.length,
(int index) {
if (index == bloc.listTest.length) {
return buildProgressIndicator(bloc.isPerformingRequest);
} else {
return bloc.listTest[index];
}
})))
],
),
);
}
});
}
void addToTimelineList(List<int> list, TestBloc bloc) {
for (var val in list) {
bloc.listTest.add(Text('$val'));
}
}
}
Widget buildProgressIndicator(showIndicator) {
return new Padding(
padding: const EdgeInsets.all(8.0),
child: new Center(
child: new Opacity(
opacity: showIndicator ? 1.0 : 0.0,
child: Container(
width: 10.0, height: 10.0, child: new CircularProgressIndicator()),
),
),
);
}
class TestBloc {
String appbar1Val;
String appbar2Val;
List<Text> listTest = new List<Text>();
bool isPerformingRequest = false;
final _testAppBarText1 = BehaviorSubject<String>();
Observable<String> get testAppBarTxt1 => _testAppBarText1.stream;
final _testAppBarText2 = BehaviorSubject<String>();
Observable<String> get testAppBarTxt2 => _testAppBarText2.stream;
final _testTimeline = PublishSubject<List<int>>();
Observable<List<int>> get getTestTimeline => _testTimeline.stream;
fetchTestTimeline() async {
List item = await Future.delayed(
Duration(seconds: 2), () => List<int>.generate(100, (i) => i));
_testTimeline.sink.add(item);
}
fetchTestAppBarTxt1() async {
appbar1Val = await Future.delayed(Duration(seconds: 2), () => "Text One");
_testAppBarText1.sink.add(appbar1Val);
}
fetchTestAppBarTxt2() async {
appbar2Val = await Future.delayed(Duration(seconds: 2), () => "Text Two");
_testAppBarText2.sink.add(appbar2Val);
}
dispose() {
_testAppBarText1.close();
_testAppBarText2.close();
_testTimeline.close();
}
}

Perform Async Operations from Data gotten from StreamBuilder before displaying

I am currently using StreamBuilder to get data from Firestore and so far, it is working good.
I currently want to perform some async operations to the data before displaying.
The code to get the data is below.
List<Model> listToDisplay = new List<Model>();
#override
Widget build(BuildContext context) {
return DefaultTabController(
length: 2,
child: Scaffold(
appBar: topBar,
body: StreamBuilder(
stream: Firestore.instance.collection('/myPath').snapshots(),
builder: (BuildContext context,
AsyncSnapshot<QuerySnapshot> snapshot) {
if(snapshot.connectionState == ConnectionState.active) {
listToDisplay.clear();
for (DocumentSnapshot _snap in snapshot.data.documents) {
Model _add = new Model.from(_snap);
listToDisplay.add(_add);
}
return TabBarView(
children: <Widget>[
ListView.builder(
itemCount: mouveList.length,
itemBuilder: (context, index) {
return Card(listToDisplay[index]);
},
),
Icon(Icons.directions_transit),
],
);
} else {
return Container(
child: Center(child: CircularProgressIndicator()));
}
})));
I tried adding the async operation in the for in loop but that did not work, it did not wait for it. Also, add await did not work because Widget build(BuildContext context) cannot be async.
#override
Widget build(BuildContext context) {
return DefaultTabController(
length: 2,
child: Scaffold(
appBar: topBar,
body: StreamBuilder(
stream: Firestore.instance.collection('/myPath').snapshots(),
builder: (BuildContext context,
AsyncSnapshot<QuerySnapshot> snapshot) {
if(snapshot.connectionState == ConnectionState.active) {
listToDisplay.clear();
for (DocumentSnapshot _snap in snapshot.data.documents) {
Model _add = new Model.from(_snap);
//Added
//_add.getCalculate(); <------- Async function
_add.Calculate(); <------ Flutter does not wait for this
await _add.Calculate(); <------ Produces an error
listToDisplay.add(_add);
}
return TabBarView(
children: <Widget>[
ListView.builder(
itemCount: mouveList.length,
itemBuilder: (context, index) {
return Card(listToDisplay[index]);
},
),
Icon(Icons.directions_transit),
],
);
} else {
return Container(
child: Center(child: CircularProgressIndicator()));
}
})));
Any ideas on how to get data as stream, perform operations on the data before displaying the data all using StreamBuilder and ListViewBuilder ?
I'm currently iterating the data from a StreamBuilder in corresponding lists and then using a ListView.builder to display each data item from List.count. The code begins with these public/file Lists...
List names = new List();
List ids = new List();
List vidImages = new List();
List numbers = new List();
Then this in my Stateful Widget Builder...
child: new StreamBuilder(
stream:
fb.child('child').orderByChild('value').onValue,
builder:
(BuildContext context, AsyncSnapshot<Event> event) {
if (event.data?.snapshot?.value == null) {
return new Card(
child: new Text(
'Network Error, Please Try again...',
style: new TextStyle(
fontSize: 12.0,
fontWeight: FontWeight.bold,
fontStyle: FontStyle.italic)),
);
} else if (event.data?.snapshot?.value != null) {
Map myMap =
event.data?.snapshot?.value; //store each map
var titles = myMap.values;
List onesTitles = new List();
List onesIds = new List();
List onesImages = new List();
List onesRank = new List();
List<Top> videos = new List();
for (var items in titles) {
var top = new Top(
videoId: items['vidId'],
rank: items['Value'],
title: items['vidTitle'],
imageString: items['vidImage']);
videos.add(top);
videos..sort((a, b) => b.rank.compareTo(a.rank));
}
for (var vids in videos) {
onesTitles.add(vids.title);
onesIds.add(vids.videoId);
onesImages.add(vids.imageString);
onesRank.add(vids.rank);
}
names = onesTitles;
ids = onesIds;
numbers = onesRank;
vidImages = onesImages;
switch (event.connectionState) {
case ConnectionState.waiting:
return new Card(
child: new Text('Loading...',
style: new TextStyle(
fontSize: 12.0,
fontWeight: FontWeight.bold,
fontStyle: FontStyle.italic)),
);
else
return new InkWell( child: new ListView.builder(
itemCount:
names == null ? 0 : names.length,
itemBuilder:
(BuildContext context, int index) {
return new Card( child: new Text(names[index]))

Flutter working with Data better

I have a FutureBuilder that gets DISTINCT dates from a local sqlite DB, then I take each date and get the messages for those dates to put them in the widget, this works fine, until you want to listen realtime to a stream or poll for new messages which rebuilds the widgets and flickers the page and then scrolls to the beginning each time. I am hoping to find a way to take all the data into some object or other widget and then group by date and order, etc.. This way I can listen to a stream for updated messages, etc..
Any help would be great, here is my code if it helps anyone see what I do, this is after I converted to Streambuilder, but same result.
new StreamBuilder(
initialData: myInitialData,
stream: msgstream,
builder: (BuildContext context, AsyncSnapshot<List<Map>> snapshot) {
switch (snapshot.connectionState) {
case ConnectionState.none:
return new Text('Waiting to start');
case ConnectionState.waiting:
return new Text('');
default:
if (snapshot.hasError) {
return new Text('Error: ${snapshot.error}');
} else {
myInitialData = snapshot.data;
return new RefreshIndicator(
child: new ListView.builder(
itemBuilder: (context, index) {
return new MyChatWidget(
datediv: snapshot.data[index]['msgdate'],
msgkey: snapshot.data[index]['msgkey'],
);
},
//itemBuilder: _itemBuilder,
controller: _scrollController,
reverse: true,
itemCount: snapshot.data.length,
),
onRefresh: _onRefresh
);
}
}
}),
This is the Widget that the StreamBuilder calls:
class MyChatWidget extends StatefulWidget {
MyChatWidget({Key key, this.datediv, this.msgkey}) : super(key: key);
final String datediv;
final String msgkey;
#override
_MyChatWidgetState createState() => new _MyChatWidgetState();
}
class _MyChatWidgetState extends State<MyChatWidget> {
List<Widget> messagelist;
int messagecount = 0;
var jsonCodec = const JsonCodec();
var mydate = '';
var _urlMessages = '';
PageStorageKey _key;
VideoPlayerController vcontroller;
//Future<http.Response> _responseFuture;
Future<List<Map>> _responseFuture;
List messList;
var mybytes;
File myimageview;
Image newimageview;
String imgStr;
String vidStr;
String vidimgstr;
bool submitting = false;
List<Map> myInitialData;
Stream<List<Map>> msgstream;
#override
void initState() {
super.initState();
if (new DateFormat.yMd().format(DateTime.parse(widget.datediv)) ==
new DateFormat.yMd().format(new DateTime.now())) {
mydate = 'Today';
} else {
mydate = new DateFormat.yMMMEd().format(DateTime.parse(widget.datediv));
}
DateChatMessage dcm =
new DateChatMessage(widget.msgkey, widget.datediv.toString());
var json = jsonCodec.encode(dcm);
_urlMessages =
'http://loop-dev.clinicalsoftworks.com/chat/messages/getbydate';
//_responseFuture = http.post(_urlMessages, body: json, headers: getAuthHeader());
_responseFuture =
ChatDB.instance.getMessagesByDate(widget.msgkey, widget.datediv);
msgstream = new Stream.fromFuture(_responseFuture);
//controller = new TabController(length: 4, vsync: this);
//_getMessages();
}
/*#override
void dispose() {
super.dispose();
if (vcontroller != null) {
vcontroller.dispose();
}
}*/
#override
Widget build(BuildContext context) {
_key = new PageStorageKey('${widget.datediv.toString()}');
return new Column(
children: <Widget>[
new Container(
child: new Text(
mydate,
textAlign: TextAlign.left,
style: new TextStyle(
color: Colors.grey,
fontWeight: FontWeight.bold,
),
),
alignment: Alignment.centerLeft,
padding: new EdgeInsets.only(left: 10.0),
),
new Container(
child: new Divider(
height: 5.0,
color: Colors.grey,
),
padding: new EdgeInsets.only(left: 10.0, right: 10.0),
),
/**/
new StreamBuilder(
initialData: myInitialData,
stream: msgstream,
builder: (BuildContext context, AsyncSnapshot<List<Map>> snapshot) {
switch (snapshot.connectionState) {
case ConnectionState.none:
return new Text('Waiting to start');
case ConnectionState.waiting:
return new Text('');
default:
myInitialData = snapshot.data;
List<dynamic> json = snapshot.data;
messagelist = [];
json.forEach((element) {
DateTime submitdate =
DateTime.parse(element['submitdate']).toLocal();
String myvideo = (element['chatvideo']);
String myimage = element['chatimage'];
String myvideoimage = element['chatvideoimage'];
File imgfile;
File vidfile;
File vidimgfile;
bool vidInit = false;
Future<Null> _launched;
String localAssetPath;
String localVideoPath;
String mymessage = element['message'].replaceAll("[\u2018\u2019]", "'");
//print('MYDATE: '+submitdate.toString());
_checkFile(File file) async {
var checkfile = await file.exists();
print('VIDEXISTS: '+checkfile.toString());
}
Future<Null> _launchVideo(String url, bool isLocal) async {
if (await canLaunchVideo(url, isLocal)) {
await launchVideo(url, isLocal);
} else {
throw 'Could not launch $url';
}
}
void _launchLocal() =>
setState(() => _launched = _launchVideo(localVideoPath, true)
);
Widget _showVideo() {
/*return new Flexible(
child: new vplayer.VideoCard(
controller: vcontroller,
title: element['referralname'],
subtitle: 'video',
),
);*/
return new Flexible(
child: new Card(
child: new Column(
children: <Widget>[
new ListTile(subtitle: new Text('Video'), title: new Text(element['referralname']),),
new GestureDetector(
onTap: _launchLocal,
child: new Image.file(
vidimgfile,
width: 150.0,
),
),
],
),
)
);
}
_initVideo() {
setState(() {vidInit = true;});
}
_onError() {
print('VIDEO INIT ERROR');
}
if (myimage != "") {
imgStr = element['chatimage'];
imgfile = new File(imgStr);
}
if (myvideo != "") {
vidStr = element['chatvideo'];
vidimgstr = element['chatvideoimage'];
vidimgfile = new File(vidimgstr);
//vidfile = new File(vidStr);
//_checkFile(vidfile);
//print('vidfile: '+vidfile.path);
localVideoPath = '$vidStr';
//print('LOCALVIDEO: '+localVideoPath);
//vcontroller = new VideoPlayerController('file://$vidStr')..initialize();
}
_showLgPic() {
Route route = new MaterialPageRoute(
settings: new RouteSettings(name: "/ShowPic"),
builder: (BuildContext context) => new ShowPic(
image: imgfile,
),
);
Navigator.of(context).push(route);
}
Widget _showGraphic() {
Widget mywidget;
if (myimage != "") {
mywidget = new GestureDetector(
child: new Image.file(
imgfile,
width: 300.0,
),
onTap: _showLgPic,
);
} else if (myvideo != "") {
mywidget = _showVideo();
} else {
mywidget = new Container();
}
return mywidget;
}
messagelist.add(
new Container(
//width: 300.0,
padding: new EdgeInsets.all(10.0),
child: new Column(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
crossAxisAlignment: CrossAxisAlignment.stretch,
mainAxisSize: MainAxisSize.min,
children: <Widget>[
new Container(
padding: new EdgeInsets.only(bottom: 5.0),
child: new Row(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
new CircleAvatar(
child: new Text(
element['sendname'][0],
style: new TextStyle(fontSize: 15.0),
),
radius: 12.0,
),
new Text(' '),
new Text(
element['sendname'],
style: new TextStyle(
fontSize: 15.0,
fontWeight: FontWeight.bold),
),
new Text(' '),
new Text(
new DateFormat.Hm().format(submitdate),
style: new TextStyle(
color: Colors.grey, fontSize: 12.0),
),
],
),
),
new Row(
children: <Widget>[
new Text(' '),
new Flexible(
child: new Text(mymessage),
)
],
),
new Container(
width: 150.0,
child: new Row(
children: <Widget>[
new Text(' '),
_showGraphic()
/*myimage != ""
? new GestureDetector(
child: new Image.file(
imgfile,
width: 300.0,
),
onTap: _showLgPic,
)
: myvideo != "" ? _showVideo() : new Container(),*/
],
)),
],
),
),
);
});
return new Column(children: messagelist);
}
},
)
],
);
}
}
Thanks for any assistance
which rebuilds the widgets and flickers the page and then scrolls to the beginning each time
To solve problem with scrolling try ScrollController. Create your own, keep it between updates and inject into List you created.
To solve flickering you could use Key for List widgets. Key should be unique identifier of message, e.g. msgkey
This example how to keep scrolloffset works for me
class SomeWidget extends StatefulWidget {
#override
_SomeWidgetState createState() => new _SomeWidgetState();
}
class _SomeWidgetState extends State<SomeWidget> {
ScrollController _scrollController;
int _count;
#override
void initState() {
super.initState();
_count = 10;
_scrollController = new ScrollController();
}
void _add() {
setState(() => _count += 5);
}
#override
Widget build(BuildContext context) {
final _titles = new List<String>.generate(_count, (i) => 'Title ${i}');
return new Scaffold(
appBar: new AppBar(
title: new Text("Demo"),
actions: <Widget>[
new IconButton(icon: new Icon(Icons.add), onPressed: _add)
],
),
body: new ListView.builder(
controller: _scrollController,
itemCount: _titles.length,
itemBuilder: (context, index) => new ListTile(
title: new Text(_titles[index]),
),
),
);
}
}

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