大家好，感谢您花时间帮助我。
我仅在移动设备上的 flutter 中使用这个库 => pub.dev dropdown_search
当我单击下拉列表时，我会使用 API 调用加载用户列表。我想将它们称为 20 by 20。第一个调用完成得很好，我显示了前 20 个用户，当我到达列表底部时，我有一个新的 API 调用来显示接下来的 20 个。这部分也有效。
我的问题是，下拉列表中的列表视图不会刷新，也不会向我显示接下来的 20 个用户，但在控制台中，我的请求仍然显示我的 20 个新用户。如果我关闭并重新打开下拉列表，列表就会更新。
我联系了开发人员，他告诉我首先尝试将 this => myKey.currentState.reassemble() 与我的scrollController一起使用，但它不起作用。
然后他解释说，为了解决我的问题，他只能看到 Streambuilder 的使用。我试过了，但是没用。
您能给我一些提示或其他什么吗？
这是我在代码中所做的一些事情。在此示例中，我没有使用 StreamBuilder。
final GlobalObjectKey<DropdownSearchState<ListValueOptionList>> myKey = new GlobalObjectKey<DropdownSearchState<ListValueOptionList>>(50);
bool isListValueModify = false;
List<delegationModele.Delegation> listDelegations = [];
int indexDelegationList;
int pageCounter = 0;
ScrollController _scrollController = ScrollController();
List<ListValueOptionList> listValueOptionListModule;
List<ListValueOptionList> listValueOptionListTypeOfDelegation;
List<ListValueOptionList> listValueOptionsUserDelegation;
List userAlreadyUse = [];
@override
void initState() {
super.initState();
_scrollController.addListener(() {
if (_scrollController.position.pixels == _scrollController.position.maxScrollExtent) {
print("Scroll event");
_loadValueOptionListSpecificPeople();
setState(() {});
myKey.currentState.reassemble();
}
});
}
@override
Widget build(BuildContext context) {
return Padding(
/// Allows resize when kerboard is open if
/// padding == MediaQuery.of(context).viewInsets
padding: padding,
child: Container(
decoration:BoxDecoration(
color: appStyleMode.primaryBackgroundColor,
borderRadius: BorderRadius.vertical(top: Radius.circular(25.0)),
),
height: modalHeight,
child: Padding(
padding: const EdgeInsets.only(left:30, top:30.0, right: 30, bottom: 20),
child: ListView(
shrinkWrap: false,
children: [
getModificationItemListDelegationBuilder(),
],
),
),
),
);
}
SingleChildScrollView getModificationItemListDelegationBuilder(){
final appStyleMode = Provider.of<AppStyleModeNotifier>(context);
return SingleChildScrollView(
child: Column(
children: [
///Add specific people
Container(
width: MediaQuery.of(context).size.width,
margin: EdgeInsets.only(bottom: 10, top: 10),
child: Text(
"${getTranslated(context, "my_delegation_specific_user")} : ",
style: TextStyle(
color: specificPeopleisEmpty ? Colors.red : appStyleMode.blackWhiteColor,
fontSize: 16,
),
textAlign: TextAlign.start,
),
),
Container(
child: ListView.builder(
shrinkWrap: true,
itemCount: delegation.userDelegationRecipients.length ?? 0,
itemBuilder: (context, index){
return specificPeople(listValueOptionsUserDelegation, index);
},
),
),
],
),
);
}
Widget specificPeople(List<ListValueOptionList> listValueOptionList, int index){
final appStyleMode = Provider.of<AppStyleModeNotifier>(context);
delegationModele.UserDelegationRecipients userDelegation = delegation.userDelegationRecipients[index];
String optionUserDescription;
if(listValueOptionList != null){
listValueOptionList.removeWhere((element) => userLoad.id.stringOf == element.idValue);
for(ListValueOptionList valueOption in listValueOptionList){
if(valueOption.idValue == userDelegation.delegationUserId){
optionUserDescription = valueOption.listValueDescription;
}
}
return Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
Container(
width: MediaQuery.of(context).size.width * 0.6,
child: DropdownSearch<ListValueOptionList>(
key: myKey,
dropdownButtonProps: DropdownButtonProps(
color: appStyleMode.blackWhiteColor
),
popupProps: PopupProps.menu(
showSelectedItems: true,
menuProps: MenuProps(
borderRadius: BorderRadius.all(Radius.circular(10.0)),
elevation: 5.0,
backgroundColor: appStyleMode.primaryBackgroundColor,
),
textStyle: TextStyle(
color: appStyleMode.blackWhiteColor
),
scrollbarProps: ScrollbarProps(
thumbVisibility: true,
thumbColor: appStyleMode.categorySelectorSelectedBackgroundColor,
interactive: true
),
listViewProps: ListViewProps(
controller: _scrollController,
shrinkWrap: true,
),
interceptCallBacks: true,
itemBuilder: (context, list, isSelected){
return new Container(
child: ListTile(
selected: isSelected,
title: Text(
list?.listValueDescription,
style: TextStyle(
color: appStyleMode.blackWhiteColor
),
),
),
);
},
loadingBuilder: (context, loadingText){
return Align(
alignment: Alignment.topCenter,
child: CircularProgressIndicator(),
);
},
emptyBuilder: (context, text){
return Align(
alignment: Alignment.topCenter,
child: Text(
"${getTranslated(context, "my_delegation_empty_search_user")}",
style: TextStyle(
color: appStyleMode.blackWhiteColor,
),
),
);
},
showSearchBox: true,
searchDelay: Duration(seconds: 1),
searchFieldProps: TextFieldProps(
decoration: InputDecoration(
enabled: true,
enabledBorder: OutlineInputBorder(
borderRadius: BorderRadius.circular(10.0),
borderSide: BorderSide(
color: appStyleMode.categorySelectorSelectedBackgroundColor,
style: BorderStyle.solid
)
),
border: OutlineInputBorder(
borderRadius: BorderRadius.circular(10.0),
borderSide: BorderSide(
style: BorderStyle.solid
)
),
prefixIcon: Icon(
Icons.search_rounded,
size: 20,
),
hintText: "${getTranslated(context, "my_delegation_search_hint_text")}",
hintStyle: TextStyle(
fontSize: 13
),
),
style: TextStyle(
color: appStyleMode.blackWhiteColor,
),
),
),
onChanged: (newValue){
//OnChanges is well used
},
compareFn: (value1, value2) => value1.idValue == value2.idValue,
dropdownDecoratorProps: DropDownDecoratorProps(
dropdownSearchDecoration: InputDecoration(
border: InputBorder.none
)
),
//items: listValueOptionsUserDelegation,
asyncItems: (filter) async{
return _loadValueOptionListSpecificPeople();
},
itemAsString: (ListValueOptionList list) => list.listValueDescription,
selectedItem: new ListValueOptionList(idValue: userDelegation.delegationUserId, listValueDescription: optionUserDescription),
dropdownBuilder: (context, selectedItem){
if(optionUserDescription == null || optionUserDescription.isEmpty){
return Container();
}else if(optionUserDescription == ""){
return Text("");
}else{
selectedItem.listValueDescription = optionUserDescription;
}
return textValueDescription(selectedItem.listValueDescription, appStyleMode, TextAlign.start);
},
),
),
],
);
}else{
return Container();
}
}
@override
void dispose() {
_scrollController.dispose();
super.dispose();
}
}
我有一个类似的应用程序。也许这段代码会有所帮助：
class PostsList extends StatefulWidget {
@override
State<PostsList> createState() => _PostsListState();
}
class _PostsListState extends State<PostsList> {
final _scrollController = ScrollController();
@override
void initState() {
super.initState();
_scrollController.addListener(_onScroll);
}
@override
Widget build(BuildContext context) {
return BlocBuilder<PostBloc, PostState>(
builder: (context, state) {
switch (state.status) {
case PostStatus.failure:
return const Center(child: Text('failed to fetch posts'));
case PostStatus.success:
if (state.posts.isEmpty) {
return const Center(child: Text('no posts'));
}
return ListView.builder(
itemBuilder: (BuildContext context, int index) {
return index >= state.posts.length
? const BottomLoader()
: PostListItem(post: state.posts[index]);
},
itemCount: state.hasReachedMax
? state.posts.length
: state.posts.length + 1,
controller: _scrollController,
);
default:
return const Center(child: CircularProgressIndicator());
}
},
);
}
@override
void dispose() {
_scrollController
..removeListener(_onScroll)
..dispose();
super.dispose();
}
void _onScroll() {
if (_isBottom) context.read<PostBloc>().add(PostFetched());
}
bool get _isBottom {
if (!_scrollController.hasClients) return false;
final maxScroll = _scrollController.position.maxScrollExtent;
final currentScroll = _scrollController.offset;
return currentScroll >= (maxScroll * 0.9);
}
}
我为此使用了 bloc，但它应该可以与未来的构建器和使用快照一起使用。基本上用户向下滚动，如果滚动超过列表的 90%，则会发送另一个 getter 以从 api 获取更多项目。如果您想复制整个集团（我强烈推荐），请查看此文档。
你在哪里可以解决这个问题？有同样的问题