我一直在尝试向我的待办事项列表中添加一个编辑功能，用户可以在其中选择要编辑的项目，然后应该弹出一个对话框，其中有一个文本字段可输入所选项目的新值，保存更改的按钮。当前，我有一个函数，该函数调用存储任务的数组，然后应该使用索引触发所选项目，以便最后在onPressed时可以给所选值一个新值，请将此编辑功能视为instagrams，除了它编辑文本。
问题是在对话框的编辑按钮中调用该函数时出现的，因为我像onPressed: () => _editToDoItem(_controller.text, index)那样执行此操作，并且由于必须在其中传递2个参数，所以我遇到的错误是Undefined name 'index'。如何解决此问题以使此编辑功能起作用？顺便说一句，由于这个错误，我没有尝试编辑功能，所以如果功能或代码的任何部分不正确，请更正我。
一切与下面的编辑功能有关。
List<ToDoElement> _toDoItems = [];
TextEditingController _controller = TextEditingController();
// this function adds a task to the list
void _addToDoItem(String task) {
if(task.isNotEmpty) {
setState(() {
_toDoItems.add(ToDoElement(task, DateTime.now()));
});
}
}
// this is the function that is supposed to edit the selected index from the _toDoItems array
void _editToDoItem(String newText, int index) {
setState(() {
_toDoItems[index].task = newText;
});
}
_editDialog(BuildContext context) {
return showDialog(context: context, builder: (context) {
return Dialog(
child: Container(
height: 180,
width: 100,
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Container(
height: 60,
child: TextField(
controller: _controller,
autofocus: true,
style: TextStyle(fontSize: 18,),
)
),
Container(
height: 65,
width: double.infinity,
margin: EdgeInsets.only(top: 5,),
child: RaisedButton(
textColor: Colors.white,
color: Colors.red,
child: Text('EDIT'),
onPressed: () {
_editToDoItem(_controller.text, index); // error on index, Undefined name 'index'
FocusScope.of(context).requestFocus(FocusNode());
},
),
),
],
),
),
);
});
}
class ToDoElement {
String task;
final DateTime timeOfCreation;
ToDoElement(this.task, this.timeOfCreation);
}
void main() => runApp(MaterialApp(home: MyApp()));
class MyApp extends StatefulWidget {
@override
createState() => MyAppState();
}
class MyAppState extends State<MyApp> {
List<ToDoElement> _toDoItems = [];
TextEditingController _controller = TextEditingController();
void _addToDoItem(String task) {
if(task.isNotEmpty) {
setState(() {
_toDoItems.add(ToDoElement(task, DateTime.now()));
});
}
}
void _editToDoItem(String newText, int index) {
setState(() {
_toDoItems[index].task = newText;
});
}
void _removeTodoItem(int index) {
setState(() => _toDoItems.removeAt(index));
}
_editDialog(BuildContext context) {
return showDialog(context: context, builder: (context) {
return Dialog(
backgroundColor: Colors.transparent,
child: Container(
decoration: BoxDecoration(
color: Colors.white,
borderRadius: BorderRadius.all(Radius.circular(20.0)),
),
padding: EdgeInsets.all(20),
height: 180,
width: 100,
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Container(
height: 60,
child: TextField(
controller: _controller,
autofocus: true,
/*onSubmitted: (val) {
_addToDoItem(val);
_controller.clear();
},*/
style: TextStyle(fontSize: 18,),
decoration: InputDecoration(
hintText: 'Add a task here...',
enabledBorder: OutlineInputBorder(
borderRadius: BorderRadius.all(Radius.circular(12.0)),
borderSide: BorderSide(color: Colors.red, width: 2),
),
focusedBorder: OutlineInputBorder(
borderRadius: BorderRadius.all(Radius.circular(12.0)),
borderSide: BorderSide(color: Colors.red, width: 2),
),
),
)
),
Container(
height: 65,
width: double.infinity,
margin: EdgeInsets.only(top: 5,),
child: RaisedButton(
textColor: Colors.white,
color: Colors.red,
child: Text('EDIT', style: TextStyle(fontSize: 18)),
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.all(Radius.circular(12)),
),
onPressed: () {
_editToDoItem(_controller.text, index);
FocusScope.of(context).requestFocus(FocusNode());
},
),
),
],
),
),
);
});
}
Widget _buildToDoItem(String toDoText, int index) {
return SizedBox(
child: Container(
height: 58,
margin: EdgeInsets.only(left: 22.0, right: 22.0, bottom: 12,),
decoration: BoxDecoration(
border: Border.all(width: 1.5, color: Colors.red),
borderRadius: BorderRadius.all(Radius.circular(18)),
),
child: Row(
crossAxisAlignment: CrossAxisAlignment.center,
children:[
Expanded(
child: ListTile(
title: Text(
toDoText,
style: TextStyle(fontSize: 18),
),
onTap: () => null,
),
),
FlatButton(
child: Text('Edit', style: TextStyle(color: Colors.red, fontSize: 16.5),),
onPressed: () => _editDialog(context),
),
FlatButton(
child: Text('Delete', style: TextStyle(color: Colors.red, fontSize: 16.5),),
onPressed: () => _removeTodoItem(index),
),
],
),
),
);
}
int compareElement(ToDoElement a, ToDoElement b) =>
a.timeOfCreation.isAfter(b.timeOfCreation) ? -1 : 1;
Widget _buildToDoList() {
_toDoItems.sort(compareElement);
return Expanded(
child: ListView.builder(
itemCount: _toDoItems.length,
itemBuilder: (context, index) {
if (index < _toDoItems.length) {
return _buildToDoItem(_toDoItems[index].task, index);
}
},
),
);
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: PreferredSize(
preferredSize: Size.fromHeight(50),
child: AppBar(
centerTitle: true,
backgroundColor: Colors.red,
title: Text('To Do List', style: TextStyle(fontSize: 24, fontWeight: FontWeight.bold,),),
)
),
backgroundColor: Colors.white,
body: GestureDetector(
onTap: () {
FocusScope.of(context).requestFocus(FocusNode());
},
child: Column(
crossAxisAlignment: CrossAxisAlignment.center,
children: [
Container(
height: 60,
margin: EdgeInsets.all(22),
child: Row(
crossAxisAlignment: CrossAxisAlignment.center,
children: [
Expanded(
flex: 10,
child: Container(
height: double.infinity,
child: TextField(
controller: _controller,
autofocus: true,
onSubmitted: (val) {
_addToDoItem(val);
_controller.clear();
},
style: TextStyle(fontSize: 18,),
decoration: InputDecoration(
hintText: 'Add a task here...',
enabledBorder: OutlineInputBorder(
borderRadius: BorderRadius.all(Radius.circular(12.0)),
borderSide: BorderSide(color: Colors.red, width: 2),
),
focusedBorder: OutlineInputBorder(
borderRadius: BorderRadius.all(Radius.circular(12.0)),
borderSide: BorderSide(color: Colors.red, width: 2),
),
),
),
),
),
Expanded(
flex: 4,
child: Container(
height: double.infinity,
margin: EdgeInsets.only(left: 12),
child: RaisedButton(
textColor: Colors.white,
color: Colors.red,
child: Text('ADD', style: TextStyle(fontSize: 18)),
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.all(Radius.circular(12)),
),
onPressed: () {
_addToDoItem(_controller.text);
_controller.clear();
FocusScope.of(context).requestFocus(FocusNode());
},
),
),
),
],
),
),
_buildToDoList()
]
),
),
);
}
}
最佳答案
您可以在下面复制粘贴运行完整代码
您可以将index提供给_editDialog，然后_editToDoItem可以获取index程式码片段
_editDialog(BuildContext context, int index)
...
FlatButton(
child: Text(
'Edit',
style: TextStyle(color: Colors.red, fontSize: 16.5),
),
onPressed: () => _editDialog(context, index),
),
完整的代码
import 'package:flutter/material.dart';
class ToDoElement {
String task;
final DateTime timeOfCreation;
ToDoElement(this.task, this.timeOfCreation);
}
void main() => runApp(MaterialApp(home: MyApp()));
class MyApp extends StatefulWidget {
@override
createState() => MyAppState();
}
class MyAppState extends State<MyApp> {
List<ToDoElement> _toDoItems = [];
TextEditingController _controller = TextEditingController();
TextEditingController _controller1 = TextEditingController();
void _addToDoItem(String task) {
if (task.isNotEmpty) {
setState(() {
_toDoItems.add(ToDoElement(task, DateTime.now()));
});
}
}
void _editToDoItem(String newText, int index) {
setState(() {
_toDoItems[index].task = newText;
});
}
void _removeTodoItem(int index) {
setState(() => _toDoItems.removeAt(index));
}
_editDialog(BuildContext context, int index) {
return showDialog(
context: context,
builder: (context) {
return Dialog(
backgroundColor: Colors.transparent,
child: Container(
decoration: BoxDecoration(
color: Colors.white,
borderRadius: BorderRadius.all(Radius.circular(20.0)),
),
padding: EdgeInsets.all(20),
height: 180,
width: 100,
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Container(
height: 60,
child: TextField(
controller: _controller,
autofocus: true,
/*onSubmitted: (val) {
_addToDoItem(val);
_controller.clear();
},*/
style: TextStyle(
fontSize: 18,
),
decoration: InputDecoration(
hintText: 'Add a task here...',
enabledBorder: OutlineInputBorder(
borderRadius:
BorderRadius.all(Radius.circular(12.0)),
borderSide: BorderSide(color: Colors.red, width: 2),
),
focusedBorder: OutlineInputBorder(
borderRadius:
BorderRadius.all(Radius.circular(12.0)),
borderSide: BorderSide(color: Colors.red, width: 2),
),
),
)),
Container(
height: 65,
width: double.infinity,
margin: EdgeInsets.only(
top: 5,
),
child: RaisedButton(
textColor: Colors.white,
color: Colors.red,
child: Text('EDIT', style: TextStyle(fontSize: 18)),
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.all(Radius.circular(12)),
),
onPressed: () {
_editToDoItem(_controller.text, index);
FocusScope.of(context).requestFocus(FocusNode());
},
),
),
],
),
),
);
});
}
Widget _buildToDoItem(String toDoText, int index) {
return SizedBox(
child: Container(
height: 58,
margin: EdgeInsets.only(
left: 22.0,
right: 22.0,
bottom: 12,
),
decoration: BoxDecoration(
border: Border.all(width: 1.5, color: Colors.red),
borderRadius: BorderRadius.all(Radius.circular(18)),
),
child: Row(
crossAxisAlignment: CrossAxisAlignment.center,
children: [
Expanded(
child: ListTile(
title: Text(
toDoText,
style: TextStyle(fontSize: 18),
),
onTap: () => null,
),
),
FlatButton(
child: Text(
'Edit',
style: TextStyle(color: Colors.red, fontSize: 16.5),
),
onPressed: () => _editDialog(context, index),
),
FlatButton(
child: Text(
'Delete',
style: TextStyle(color: Colors.red, fontSize: 16.5),
),
onPressed: () => _removeTodoItem(index),
),
],
),
),
);
}
int compareElement(ToDoElement a, ToDoElement b) =>
a.timeOfCreation.isAfter(b.timeOfCreation) ? -1 : 1;
Widget _buildToDoList() {
_toDoItems.sort(compareElement);
return Expanded(
child: ListView.builder(
itemCount: _toDoItems.length,
itemBuilder: (context, index) {
if (index < _toDoItems.length) {
return _buildToDoItem(_toDoItems[index].task, index);
}
},
),
);
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: PreferredSize(
preferredSize: Size.fromHeight(50),
child: AppBar(
centerTitle: true,
backgroundColor: Colors.red,
title: Text(
'To Do List',
style: TextStyle(
fontSize: 24,
fontWeight: FontWeight.bold,
),
),
)),
backgroundColor: Colors.white,
body: GestureDetector(
onTap: () {
FocusScope.of(context).requestFocus(FocusNode());
},
child: Column(crossAxisAlignment: CrossAxisAlignment.center, children: [
Container(
height: 60,
margin: EdgeInsets.all(22),
child: Row(
crossAxisAlignment: CrossAxisAlignment.center,
children: [
Expanded(
flex: 10,
child: Container(
height: double.infinity,
child: TextField(
controller: _controller1,
autofocus: true,
onSubmitted: (val) {
_addToDoItem(val);
_controller1.clear();
},
style: TextStyle(
fontSize: 18,
),
decoration: InputDecoration(
hintText: 'Add a task here...',
enabledBorder: OutlineInputBorder(
borderRadius: BorderRadius.all(Radius.circular(12.0)),
borderSide: BorderSide(color: Colors.red, width: 2),
),
focusedBorder: OutlineInputBorder(
borderRadius: BorderRadius.all(Radius.circular(12.0)),
borderSide: BorderSide(color: Colors.red, width: 2),
),
),
),
),
),
Expanded(
flex: 4,
child: Container(
height: double.infinity,
margin: EdgeInsets.only(left: 12),
child: RaisedButton(
textColor: Colors.white,
color: Colors.red,
child: Text('ADD', style: TextStyle(fontSize: 18)),
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.all(Radius.circular(12)),
),
onPressed: () {
_addToDoItem(_controller1.text);
_controller1.clear();
FocusScope.of(context).requestFocus(FocusNode());
},
),
),
),
],
),
),
_buildToDoList()
]),
),
);
}
}
关于flutter - 如何在Flutter中编辑列表中的选定项目，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/63404236/