我正在尝试将 Hive Box 从主屏幕传递到下一个屏幕，但无法做到。我尝试在 MaterialPageRoute 时使用 Box 类型，但它没有用。
我正在接受来自用户的数据并尝试对它们进行 CRUD 操作。我还想将一个蜂巢盒从一页传递到下一页
import 'dart:io';
import 'package:flutter/material.dart';
import 'package:fluttertoast/fluttertoast.dart';
import 'package:hive/hive.dart';
import 'package:path_provider/path_provider.dart';
void main() async {
WidgetsFlutterBinding.ensureInitialized();
Directory dir = await getExternalStorageDirectory();
Hive.init(dir.path);
print(dir.path);
await Hive.openBox<String>('box1');
runApp(MyApp());
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(title: 'Hive Storage Test Run'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
String name, pass;
Box<String> box2;
TextEditingController _fullname = TextEditingController();
TextEditingController _password = TextEditingController();
@override
void initState() {
super.initState();
box2 = Hive.box<String>('box1');
}
bool _showpass = false;
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
//Full name
TextField(
controller: _fullname,
decoration: InputDecoration(labelText: 'Enter Full name'),
onSubmitted: (String value) {
name = value;
Fluttertoast.showToast(msg: 'Welcome ${name}');
},
),
//Password
TextField(
controller: _password,
obscureText: !this._showpass,
decoration: InputDecoration(
labelText: 'Enter Password',
suffixIcon: IconButton(
icon: Icon(
Icons.remove_red_eye_outlined,
color: this._showpass ? Colors.redAccent : Colors.blueAccent,
),
onPressed: () {
setState(() => this._showpass = !this._showpass);
},
),
),
onSubmitted: (String value) {
pass = value;
Fluttertoast.showToast(msg: 'Password is ${pass}');
},
),
SizedBox(height: 100,),
Column(
children: <Widget>[
Row(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: <Widget>[
RaisedButton(
child: Text('Save'),
onPressed: () {
final key = _fullname.text;
final value = _password.text;
box2.put(key, value);
print(key);
print(value);
setState(() {
_fullname = TextEditingController(text: "");
_password = TextEditingController(text: "");
});
},
),
RaisedButton(
child: Text('Print Values'),
onPressed: () {
print(box2.getAt(0));
},
),
],
),
SizedBox(height: 30.0,),
Row(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: <Widget>[
RaisedButton(
child: Text('Load'),
onPressed: () {
if(box2.isEmpty == true){
Fluttertoast.showToast(msg: "No data present. Please enter new data");
}else{
Box box3 = box2;
Navigator.of(context)
.push(
MaterialPageRoute(
builder: (context) => Page2(box3: box3),
)
);
}
},
),
RaisedButton(
child: Text("Empty Data"),
onPressed: () {
box2.clear();
},
),
],
),
],
),
],
),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
class Page2 extends StatefulWidget {
Box box3;
Page2({box3});
@override
_Page2State createState() => _Page2State(box3);
}
class _Page2State extends State<Page2> {
Box box3;
_Page2State(this.box3);
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Page 2"),
),
body: Center(
child: Column(
children: <Widget>[
Text("Page 2"),
Text(box3.getAt(0)),
RaisedButton(
onPressed: () {
child: Text("Back");
Navigator.of(context).pop();
},
)
],
),
),
);
}
}
我需要将 box2 从 MyHomePage 传递到 Page2
这是我的错误....
The following NoSuchMethodError was thrown building Page2(dirty, state: _Page2State#33882):
The method 'getAt' was called on null.
Receiver: null
Tried calling: getAt(0)
The relevant error-causing widget was:
Page2 file:///C:/Users/harsh/AndroidStudioProjects/storage/lib/main.dart:142:53
When the exception was thrown, this was the stack:
#0 Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5)
#1 _Page2State.build (package:storage/main.dart:190:23)
#2 StatefulElement.build (package:flutter/src/widgets/framework.dart:4744:28)
#3 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4627:15)
#4 StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4800:11)
...