Adding filter button to different screens - flutter

Question

I have a working filter button in search page of my app
I need to add it as floating button in other pages such as category, view all products etc
Here is the working filter button code for searchscreen.
class SearchProductWidget extends StatelessWidget {
final bool isViewScrollable;
final List<Product> products;
SearchProductWidget({this.isViewScrollable, this.products});
#override
Widget build(BuildContext context) {
return Padding(
padding: EdgeInsets.all(Dimensions.PADDING_SIZE_SMALL),
child: Column(
children: [
Row(
children: [
Expanded(
child: Text(
'Search result for \"${Provider.of<SearchProvider>(context).searchText}\" (${products.length} items)',
style: titilliumRegular.copyWith(
fontSize: Dimensions.FONT_SIZE_DEFAULT),
maxLines: 1,
overflow: TextOverflow.ellipsis,
),
),
InkWell(
onTap: () => showModalBottomSheet(
context: context,
isScrollControlled: true,
backgroundColor: Colors.transparent,
builder: (c) => SearchFilterBottomSheet()),
child: Container(
padding: EdgeInsets.symmetric(
vertical: Dimensions.PADDING_SIZE_EXTRA_SMALL,
horizontal: Dimensions.PADDING_SIZE_SMALL),
decoration: BoxDecoration(
color: ColorResources.getLowGreen(context),
borderRadius: BorderRadius.circular(5),
border: Border.all(
width: 1, color: Theme.of(context).hintColor),
),
child: Row(children: [
///Image.asset(Images.filter_image, width: 10, height: 10, color: ColorResources.getPrimary(context)),
SizedBox(width: Dimensions.PADDING_SIZE_EXTRA_SMALL),
Text('Filter'),
]),
),
),
],
),
SizedBox(height: Dimensions.PADDING_SIZE_SMALL),
Expanded(
child: StaggeredGridView.countBuilder(
physics: BouncingScrollPhysics(),
padding: EdgeInsets.all(0),
crossAxisCount: 2,
itemCount: products.length,
//shrinkWrap: true,
staggeredTileBuilder: (int index) => StaggeredTile.fit(1),
itemBuilder: (BuildContext context, int index) {
return ProductWidget(productModel: products[index]);
},
),
),
],
),
);
}
}
I'm trying to create a floating action button to work as a filter in different screens
Here is one of the screen which I need the filter button working-
class AllProductScreen extends StatelessWidget {
final ScrollController _scrollController = ScrollController();
final ProductType productType;
AllProductScreen({#required this.productType});
// Future<void> _loadData(BuildContext context, bool reload) async {
// String _languageCode = Provider.of<LocalizationProvider>(context, listen: false).locale.countryCode;
// await Provider.of<BrandProvider>(context, listen: false).getBrandList(reload, context);
// await Provider.of<ProductProvider>(context, listen: false).getLatestProductList('1', context, _languageCode, reload: reload);
//
//
//
// }
#override
Widget build(BuildContext context) {
// _loadData(context, false);
return Scaffold(
backgroundColor: ColorResources.getHomeBg(context),
resizeToAvoidBottomInset: false,
appBar: AppBar(
backgroundColor: Provider.of<ThemeProvider>(context).darkTheme
? Colors.black
: Theme.of(context).primaryColor,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.only(
bottomRight: Radius.circular(5),
bottomLeft: Radius.circular(5))),
leading: IconButton(
icon:
Icon(Icons.arrow_back_ios, size: 20, color: ColorResources.WHITE),
onPressed: () => Navigator.of(context).pop(),
),
title: Text(
productType == ProductType.FEATURED_PRODUCT
? 'Featured Product'
: 'Latest Product',
style: titilliumRegular.copyWith(
fontSize: 20, color: ColorResources.WHITE)),
),
floatingActionButton: FloatingActionButton.extended(
onPressed: () => showModalBottomSheet(
context: context,
isScrollControlled: true,
backgroundColor: Colors.transparent,
builder: (c) => SearchFilterBottomSheet()),
icon: const Icon(Icons.filter_list),
label: const Text('Filter'),
),
floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
body: SafeArea(
child: RefreshIndicator(
backgroundColor: Theme.of(context).primaryColor,
onRefresh: () async {
// await _loadData(context, true);
return true;
},
child: CustomScrollView(
controller: _scrollController,
slivers: [
SliverToBoxAdapter(
child: Padding(
padding: EdgeInsets.all(Dimensions.PADDING_SIZE_SMALL),
child: ProductView(
isHomePage: false,
productType: productType,
scrollController: _scrollController),
),
),
],
),
),
),
);
}
}
The exception I'm getting is
════════════════════════════════════════════════════════════════════════════════
════════ Exception caught by gesture ═══════════════════════════════════════════
The getter 'iterator' was called on null.
Receiver: null
Tried calling: iterator