A simple custom stream builder library based on BLOC pattern. Uses stream underneath.
Features
This allows easy adding of data from network and disposing of bloc
How To Use Custom Bloc
void main() async {
String type = 'multi';
WidgetsFlutterBinding.ensureInitialized();
runApp(MaterialApp(
home: type == 'one'
? const Example()
: type == 'two'
? const Example2()
: const ExampleMulti(),
));
}
class Example extends StatefulWidget {
const Example({Key? key}) : super(key: key);
@override
State<Example> createState() => _ExampleState();
}
class _ExampleState extends State<Example> {
final counterBloc = CounterBloc();
@override
void dispose() {
super.dispose();
counterBloc.dispose();
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: Column(
children: [
Expanded(
child: CustomStreamBuilder(
stream: counterBloc.behaviorSubject,
dataBuilder: (context, data) {
return ListView.separated(
itemCount: 1,
scrollDirection: Axis.horizontal,
padding:
const EdgeInsets.symmetric(horizontal: 4, vertical: 24),
itemBuilder: (context, index) {
return Padding(
padding: const EdgeInsets.symmetric(horizontal: 12),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
Text(
'index: $index: data: $data',
style: const TextStyle(fontSize: 34),
),
],
));
},
separatorBuilder: (context, index) {
return const Padding(
padding: EdgeInsets.symmetric(vertical: 10.0),
child: VerticalDivider(),
);
},
);
},
loadingBuilder: (context) => const Center(
child: CircularProgressIndicator(),
),
errorBuilder: (context, error) => Text(
error,
style: const TextStyle(),
),
),
),
const SizedBox(
height: 34,
),
Row(
children: [
TextButton(
onPressed: () {
counterBloc.fetchCurrent(false);
},
child: const Text(
'Add Value',
style: TextStyle(),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
counterBloc.resetData();
},
child: const Text(
'Set to no data',
style: TextStyle(),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
counterBloc.fetchCurrent(true);
},
child: const Text(
'Add Error',
style: TextStyle(),
)),
],
),
const SizedBox(
height: 34,
)
],
),
),
);
}
}
class CounterBloc extends BaseBloc<int, String> {
int value = 0;
CounterBloc() {
fetchCurrent(false);
}
fetchCurrent(bool addError) async {
setAsLoading();
if (!addError) {
await Future.delayed(const Duration(seconds: 2));
value++;
addToModel(value);
} else {
value = 0;
addToError('Could not fetch data');
}
}
resetData() {
value = 0;
setAsNoContent();
}
invalidate() {
invalidateBaseBloc();
}
dispose() {
disposeBaseBloc();
}
}
class Example2 extends StatefulWidget {
const Example2({Key? key}) : super(key: key);
@override
State<Example2> createState() => _Example2State();
}
class _Example2State extends State<Example2> {
final counterBloc = CounterBloc();
final newCounterBloc = CounterBloc2();
@override
void dispose() {
super.dispose();
counterBloc.dispose();
newCounterBloc.dispose();
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: Column(
children: [
Expanded(
child: CustomStreamBuilder.twoSubject(
streams: [
counterBloc.behaviorSubject,
newCounterBloc.behaviorSubject
],
dataBuilder2: (context, BaseModel<int?, String?> data,
BaseModel<double?, String?> secondData) {
var counterBlocData = data.model;
var counterBlocState = data.itemState;
var counterBlocDataError = data.error;
var newCounterBlocData = secondData.model;
var newCounterBlocState = secondData.itemState;
var newCounterBlocError = secondData.error;
return Padding(
padding: const EdgeInsets.symmetric(horizontal: 12),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
if (counterBlocState == ItemState.loading)
const Center(
child: CircularProgressIndicator(),
)
else if (counterBlocState == ItemState.hasError)
Text(
'counterBlocData error: $counterBlocDataError',
style: const TextStyle(fontSize: 34),
)
else if (counterBlocState == ItemState.noContent)
const SizedBox()
else
Text(
'counterBlocData: $counterBlocData',
style: const TextStyle(fontSize: 34),
),
const SizedBox(
height: 34,
),
if (newCounterBlocState == ItemState.loading)
const Center(
child: CircularProgressIndicator(),
)
else if (newCounterBlocState == ItemState.hasError)
Text(
'newCounterBlocError error: $newCounterBlocError',
style: const TextStyle(fontSize: 34),
)
else if (newCounterBlocState == ItemState.noContent)
const SizedBox()
else
Text(
'newCounterBlocData: $newCounterBlocData',
style: const TextStyle(fontSize: 34),
),
],
));
},
loadingBuilder: (context) => const Center(
child: CircularProgressIndicator(),
),
errorBuilder: (context, error) => Text(
error.toString(),
style: const TextStyle(),
),
),
),
const SizedBox(
height: 34,
),
Wrap(
children: [
TextButton(
onPressed: () {
counterBloc.fetchCurrent(false);
},
child: const Text(
'Add Value to stream 1',
style: TextStyle(),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
counterBloc.resetData();
},
child: const Text(
'Set to no data stream 1',
style: TextStyle(),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
counterBloc.fetchCurrent(true);
},
child: const Text(
'Add Error to stream 1',
style: TextStyle(),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
newCounterBloc.fetchCurrent(false);
},
child: const Text(
'Add Value to stream 2',
style: TextStyle(color: Colors.red),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
newCounterBloc.resetData();
},
child: const Text(
'Set to no data stream 2',
style: TextStyle(color: Colors.red),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
newCounterBloc.fetchCurrent(true);
},
child: const Text(
'Add Error to stream 2',
style: TextStyle(color: Colors.red),
)),
],
),
const SizedBox(
height: 34,
)
],
),
),
);
}
}
class CounterBloc2 extends BaseBlocInfiniteLoadingFactoryBloc<double, String> {
double value = 0;
fetchCurrent(bool addError) async {
setAsLoading();
if (!addError) {
await Future.delayed(const Duration(seconds: 2));
value += 0.5;
addToModel(value);
} else {
value = 0;
addToError('Could not fetch data');
}
}
@override
fetchNextPage(
{Function()? startLoadingMore, Function()? stopLoadingMore}) async {
await Future.delayed(const Duration(seconds: 2));
value += 0.5;
addToModel(value);
}
resetData() {
value = 0;
setAsNoContent();
}
invalidate() {
invalidateBaseBloc();
}
dispose() {
disposeBaseBloc();
}
}
class ExampleMulti extends StatefulWidget {
const ExampleMulti({Key? key}) : super(key: key);
@override
State<ExampleMulti> createState() => _ExampleMultiState();
}
class _ExampleMultiState extends State<ExampleMulti> {
final counterBloc = CounterBloc();
final newCounterBloc = CounterBloc2();
final newCounterBloc3 = CounterBloc3();
@override
void dispose() {
super.dispose();
counterBloc.dispose();
newCounterBloc.dispose();
newCounterBloc3.dispose();
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: Column(
children: [
Expanded(
child: CustomStreamBuilder.multiSubject(
streams: [
counterBloc.behaviorSubject,
newCounterBloc.behaviorSubject,
newCounterBloc3.behaviorSubject
],
itemBuilderMulti: (context, data) {
var counterBlocData = data.first.model as int?;
var counterBlocState = data.first.itemState;
var counterBlocDataError = data.first.error as String?;
var newCounterBlocData = data.elementAt(1).model as double?;
var newCounterBlocState = data.elementAt(1).itemState;
var newCounterBlocError = data.elementAt(1).error as String?;
var newCounterBlocData3 = data.elementAt(2).model as double?;
var newCounterBlocState3 = data.elementAt(2).itemState;
var newCounterBlocError3 = data.elementAt(2).error as String?;
return Padding(
padding: const EdgeInsets.symmetric(horizontal: 12),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
if (counterBlocState == ItemState.loading)
const Center(
child: CircularProgressIndicator(),
)
else if (counterBlocState == ItemState.hasError)
Text(
'counterBlocData error: $counterBlocDataError',
style: const TextStyle(fontSize: 34),
)
else if (counterBlocState == ItemState.noContent)
const SizedBox()
else
Text(
'counterBlocData: $counterBlocData',
style: const TextStyle(fontSize: 34),
),
const SizedBox(
height: 34,
),
if (newCounterBlocState == ItemState.loading)
const Center(
child: CircularProgressIndicator(),
)
else if (newCounterBlocState == ItemState.hasError)
Text(
'newCounterBlocError error: $newCounterBlocError',
style: const TextStyle(fontSize: 34),
)
else if (newCounterBlocState == ItemState.noContent)
const SizedBox()
else
Text(
'newCounterBlocData: $newCounterBlocData',
style: const TextStyle(fontSize: 34),
),
if (newCounterBlocState3 == ItemState.loading)
const Center(
child: CircularProgressIndicator(),
)
else if (newCounterBlocState3 == ItemState.hasError)
Text(
'newCounterBlocError error: $newCounterBlocError3',
style: const TextStyle(fontSize: 34),
)
else if (newCounterBlocState3 == ItemState.noContent)
const SizedBox()
else
Text(
'newCounterBlocData: $newCounterBlocData3',
style: const TextStyle(fontSize: 34),
),
],
));
},
),
),
const SizedBox(
height: 34,
),
Wrap(
children: [
TextButton(
onPressed: () {
counterBloc.fetchCurrent(false);
},
child: const Text(
'Add Value to stream 1',
style: TextStyle(),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
counterBloc.resetData();
},
child: const Text(
'Set to no data stream 1',
style: TextStyle(),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
counterBloc.fetchCurrent(true);
},
child: const Text(
'Add Error to stream 1',
style: TextStyle(),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
newCounterBloc.fetchCurrent(false);
},
child: const Text(
'Add Value to stream 2',
style: TextStyle(color: Colors.red),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
newCounterBloc.resetData();
},
child: const Text(
'Set to no data stream 2',
style: TextStyle(color: Colors.red),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
newCounterBloc.fetchCurrent(true);
},
child: const Text(
'Add Error to stream 2',
style: TextStyle(color: Colors.red),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
newCounterBloc3.fetchCurrent(false);
},
child: const Text(
'Add Value to stream 3',
style: TextStyle(color: Colors.purple),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
newCounterBloc3.resetData();
},
child: const Text(
'Set to no data stream 3',
style: TextStyle(color: Colors.purple),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
newCounterBloc3.fetchCurrent(true);
},
child: const Text(
'Add Error to stream 3',
style: TextStyle(color: Colors.purple),
)),
],
),
const SizedBox(
height: 34,
)
],
),
),
);
}
}
class CounterBloc3 extends BaseBloc<double, String> {
double value = 0;
CounterBloc3() {
fetchCurrent(false);
}
fetchCurrent(bool addError) async {
setAsLoading();
if (!addError) {
await Future.delayed(const Duration(seconds: 2));
value += 0.5;
addToModel(value);
} else {
value = 0;
addToError('Could not fetch data');
}
}
resetData() {
value = 0;
setAsNoContent();
}
invalidate() {
invalidateBaseBloc();
}
dispose() {
disposeBaseBloc();
}
}
class ExampleCustomBlocBuilder extends StatefulWidget {
const ExampleCustomBlocBuilder({Key? key}) : super(key: key);
@override
State<ExampleCustomBlocBuilder> createState() =>
_ExampleCustomBlocBuilderState();
}
class _ExampleCustomBlocBuilderState extends State<ExampleCustomBlocBuilder> {
final counterBloc = CounterBloc();
@override
void dispose() {
super.dispose();
counterBloc.dispose();
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: Column(
children: [
Expanded(
child: CustomBlocBuilder(
stream: counterBloc.behaviorSubject,
builder: (context, itemState, data, error) {
if (itemState == ItemState.hasData) {
return ListView.separated(
itemCount: 1,
scrollDirection: Axis.horizontal,
padding: const EdgeInsets.symmetric(
horizontal: 4, vertical: 24),
itemBuilder: (context, index) {
return Padding(
padding:
const EdgeInsets.symmetric(horizontal: 12),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
Text(
'index: $index: data: $data',
style: const TextStyle(fontSize: 34),
),
],
));
},
separatorBuilder: (context, index) {
return const Padding(
padding: EdgeInsets.symmetric(vertical: 10.0),
child: VerticalDivider(),
);
},
);
} else if (itemState == ItemState.loading) {
return const Center(
child: CircularProgressIndicator(),
);
} else if (itemState == ItemState.loading) {
return Text(
error ?? '',
style: const TextStyle(),
);
}
return const SizedBox();
}),
),
const SizedBox(
height: 34,
),
Row(
children: [
TextButton(
onPressed: () {
counterBloc.fetchCurrent(false);
},
child: const Text(
'Add Value',
style: TextStyle(),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
counterBloc.resetData();
},
child: const Text(
'Set to no data',
style: TextStyle(),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
counterBloc.fetchCurrent(true);
},
child: const Text(
'Add Error',
style: TextStyle(),
)),
],
),
const SizedBox(
height: 34,
)
],
),
),
);
}
}
class CounterInfiniteScrollingBloc
extends BaseBlocInfiniteLoadingFactoryBloc<double, String> {
int get page => pageNumber;
int get itemsPerPage => perPage;
double value = 0;
initFetch() async {
setAsLoading();
await Future.delayed(const Duration(seconds: 2));
value += 0.5;
addToModel(value);
incrementPageCountAndStartLoadingMore();
}
@override
fetchNextPage(
{Function()? startLoadingMore, Function()? stopLoadingMore}) async {
bool isSuccessful = await Future.delayed(const Duration(seconds: 2));
if (isSuccessful) {
value += 0.5;
addToModel(value);
if (startLoadingMore != null) {
startLoadingMore();
}
} else {
if (stopLoadingMore != null) {
stopLoadingMore();
}
}
}
resetData() {
value = 0;
setAsNoContent();
}
@override
invalidate() {
super.invalidate();
}
@override
dispose() {
super.dispose();
}
}
class ExampleInfiniteScrolling extends StatefulWidget {
const ExampleInfiniteScrolling({Key? key}) : super(key: key);
@override
State<ExampleInfiniteScrolling> createState() =>
_ExampleInfiniteScrollingState();
}
class _ExampleInfiniteScrollingState extends State<ExampleInfiniteScrolling> {
final counterBloc = CounterInfiniteScrollingBloc();
@override
void dispose() {
super.dispose();
counterBloc.dispose();
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: Column(
children: [
Expanded(
child: CustomInfiniteScrollingStreamBuilder(
loaderStream: counterBloc.loadingMoreStream,
builder: (context, loadingData) => CustomStreamBuilder(
stream: counterBloc.behaviorSubject,
dataBuilder: (context, data) {
return NotificationListener(
onNotification: (notification) {
if (notification is ScrollNotification) {
counterBloc.sinkScrollNotification.add(notification);
}
return true;
},
child: ListView.separated(
itemCount: 1,
scrollDirection: Axis.horizontal,
padding: const EdgeInsets.symmetric(
horizontal: 4, vertical: 24),
itemBuilder: (context, index) {
return Padding(
padding:
const EdgeInsets.symmetric(horizontal: 12),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
Text(
'index: $index: data: $data',
style: const TextStyle(fontSize: 34),
),
],
));
},
separatorBuilder: (context, index) {
return const Padding(
padding: EdgeInsets.symmetric(vertical: 10.0),
child: VerticalDivider(),
);
},
),
);
},
loadingBuilder: (context) => const Center(
child: CircularProgressIndicator(),
),
errorBuilder: (context, error) => Text(
error,
style: const TextStyle(),
),
),
),
),
const SizedBox(
height: 34,
),
Row(
children: [
TextButton(
onPressed: () {
counterBloc.fetchNextPage();
},
child: const Text(
'Add Value',
style: TextStyle(),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
counterBloc.resetData();
},
child: const Text(
'Set to no data',
style: TextStyle(),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
counterBloc.fetchNextPage();
},
child: const Text(
'Add Error',
style: TextStyle(),
)),
],
),
const SizedBox(
height: 34,
)
],
),
),
);
}
}
class ExampleInfiniteScrollingWithCustomBlocBuilder extends StatefulWidget {
const ExampleInfiniteScrollingWithCustomBlocBuilder({Key? key})
: super(key: key);
@override
State<ExampleInfiniteScrollingWithCustomBlocBuilder> createState() =>
_ExampleInfiniteScrollingWithCustomBlocBuilderState();
}
class _ExampleInfiniteScrollingWithCustomBlocBuilderState
extends State<ExampleInfiniteScrollingWithCustomBlocBuilder> {
final counterBloc = CounterInfiniteScrollingBloc();
@override
void dispose() {
super.dispose();
counterBloc.dispose();
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: Column(
children: [
Expanded(
child: CustomInfiniteScrollingStreamBuilder(
loaderStream: counterBloc.loadingMoreStream,
builder: (context, loadingData) => CustomInfiniteBlocBuilder(
loadingMoreStream: counterBloc.loadingMoreStream,
stream: counterBloc.behaviorSubject,
builder: (context, state, isLoadingMore, data, error) {
if (state == ItemState.loading) {
return const Center(
child: CircularProgressIndicator(),
);
}
if (state == ItemState.hasError) {
return Text(
'$error',
style: const TextStyle(),
);
}
return NotificationListener(
onNotification: (notification) {
if (notification is ScrollNotification) {
counterBloc.sinkScrollNotification.add(notification);
}
return true;
},
child: ListView.separated(
itemCount: 1,
scrollDirection: Axis.horizontal,
padding: const EdgeInsets.symmetric(
horizontal: 4, vertical: 24),
itemBuilder: (context, index) {
return Padding(
padding:
const EdgeInsets.symmetric(horizontal: 12),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
Text(
'index: $index: data: $data',
style: const TextStyle(fontSize: 34),
),
],
));
},
separatorBuilder: (context, index) {
return const Padding(
padding: EdgeInsets.symmetric(vertical: 10.0),
child: VerticalDivider(),
);
},
),
);
},
),
),
),
const SizedBox(
height: 34,
),
Row(
children: [
TextButton(
onPressed: () {
counterBloc.fetchNextPage();
},
child: const Text(
'Add Value',
style: TextStyle(),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
counterBloc.resetData();
},
child: const Text(
'Set to no data',
style: TextStyle(),
)),
const SizedBox(
width: 34,
),
TextButton(
onPressed: () {
counterBloc.fetchNextPage();
},
child: const Text(
'Add Error',
style: TextStyle(),
)),
],
),
const SizedBox(
height: 34,
)
],
),
),
);
}
}