[英]Using Dart in Flutter, how do I add to a list of maps that is inside of a list of maps?
[英]Using Dart and Flutter, how can I save data from a dynamic widget, into a list of maps, that is inside of another list
抱歉,如果已經有人問過這個問題。
下面是我正在構建的應用程序的簡化版本的代碼。
void main() {
runApp(MaterialApp(
debugShowCheckedModeBanner: false,
home: MyApp(),
));
}
class MyApp extends StatefulWidget {
@override
State<MyApp> createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
TextEditingController dutyDescriptionController = TextEditingController();
//this list holds a list of DynamicWidgets()
List<DynamicWidget> dynamicList = [];
//this list holds a list of duties
List<Map<String, dynamic>> dutiesList = [];
//this list holds a list of activities within a duty, currently just dummy data
List<Map<String, dynamic>> activitiesList = [
{'description': 'Some Activity 1'},
{'description': 'Some Activity 2'},
];
//add DynamicWidget to the dynamicList (max of 3 widgets)
addDynamic() {
if (dynamicList.length <= 2) {
dynamicList.add(DynamicWidget());
setState(() {});
}
}
//submit the data
submitData() {
//there should only be 1 element in the duties list hence why I clear the list prior to adding to it
//not sure if this is the correct way to go about it
dutiesList.clear();
dutiesList.add({
'dutyDescription': dutyDescriptionController.text,
'activityDescription': activitiesList,
});
print(dutiesList);
//completely stuck here.
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Dynamic Widget'),
),
body: ListView(
children: [
TextField(
controller: dutyDescriptionController,
decoration: InputDecoration(labelText: 'Duty Description'),
),
Expanded(
flex: 1,
child: ListView.builder(
shrinkWrap: true,
physics: NeverScrollableScrollPhysics(),
itemCount: dynamicList.length,
itemBuilder: (BuildContext context, int index) => dynamicList[index],
),
),
ElevatedButton(
onPressed: addDynamic,
child: Text('Add Activity'),
),
],
),
floatingActionButton: FloatingActionButton(
onPressed: () {
submitData();
},
child: Icon(Icons.save),
),
);
}
}
//this widget is created dynamically and displayed in a listview.builder inside MyApp()
class DynamicWidget extends StatelessWidget {
final TextEditingController controller1 = TextEditingController();
@override
Widget build(BuildContext context) {
return TextField(
controller: controller1,
decoration: InputDecoration(labelText: 'Activity Description'),
);
}
}
該應用程序有一個文本字段,用於存儲輪班工作的職責。
下面是一個標有“添加活動”的按鈕。 按下時,它會將 DynamicWidget() 添加到 dynamicList 中,該 dynamicList 與 listview.builder 結合使用以顯示小部件。
還有一個浮動操作按鈕,當按下該按鈕時,當前會將“職責描述”文本字段的內容添加到職責列表列表以及活動列表的內容(當前使用虛擬數據進行硬編碼)。
這就是數據目前在 dutiesList 中的顯示方式。 如果不是很明顯,鍵“activityDescription”是我將存儲活動列表的地方。
[
{
dutyDescription: SomeDuty,
activityDescription: [
{
description: SomeActivity1
},
{
description: SomeActivity2
}
]
}
]
我想要做的是從一個空的 activitiesList 開始並將“活動描述”文本字段的內容(因為會有多個文本字段以及位於生產應用程序中 DynamicWidget 內部的其他用戶輸入源)添加到 activitiesList 但我不知道該怎么做。
我對 Flutter 還很陌生,學習速度很快,但我已經盯着它看了很長時間了。 任何幫助都是極好的。
提前致謝。
你真的試過運行這段代碼嗎? 我無法想象另一個 ListView 內的 Expanded 內的 ListView 不會導致錯誤。
如果“應該只有 1 個元素”,為什么要將“職責”列為一個列表?
您要求的解決方案:
為了整潔起見,將以下 function 放在_MyAppState
旁邊, addDynamic
和submitData
旁邊
void update(String description) {
setState(() {
activitiesList.add({'description': description});
});
}
然后將DynamicWidget
更改為類似
class DynamicWidget extends StatefulWidget {
final Function update;
DynamicWidget({required this.update});
@override
_DynamicWidgetState createState() => _DynamicWidgetState();
}
class _DynamicWidgetState extends State<DynamicWidget> {
String description = '';
@override
Widget build(BuildContext context) {
return SizedBox(
height: 80.0,
width: 350.0,
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: [
SizedBox(
width: 300.0,
child: TextField(
onChanged: (String text) {
setState(() {
description = text;
});
},
decoration: InputDecoration(labelText: 'Activity Description'),
),
),
IconButton(
icon: const Icon(Icons.arrow_forward),
tooltip: 'Submit',
onPressed: () => widget.update(description),
),
],
),
);
}
}
像這樣調用DynamicWidget
DynamicWidget(update: update)
如果您在提交之前和之后打印activitiesList
,您將看到您輸入的任何內容都已添加。
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