英文:
Error: The method 'fromBytes' isn't defined for the type 'VCard' in Flutter
问题
I've translated the relevant code portions for you. Here's your updated code:
import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:qr_code_scanner/qr_code_scanner.dart';
import 'package:vcard/vcard.dart';
class QRScanPage extends StatefulWidget {
@override
_QRScanPageState createState() => _QRScanPageState();
}
class _QRScanPageState extends State<QRScanPage> {
final GlobalKey qrKey = GlobalKey(debugLabel: 'QR');
Barcode? result;
QRViewController? controller;
TextEditingController nameController = TextEditingController();
TextEditingController emailController = TextEditingController();
@override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
children: <Widget>[
Expanded(
flex: 5,
child: QRView(
key: qrKey,
onQRViewCreated: _onQRViewCreated,
),
),
Expanded(
flex: 1,
child: Center(
child: Column(
children: [
TextField(
controller: nameController,
decoration: InputDecoration(
labelText: 'Name',
),
),
TextField(
controller: emailController,
decoration: InputDecoration(
labelText: 'Email',
),
),
],
),
),
)
],
),
);
}
void _onQRViewCreated(QRViewController controller) {
this.controller = controller;
controller.scannedDataStream.listen((scanData) {
setState(() {
result = scanData;
parseVCard(result!.code);
});
});
}
void parseVCard(String vCardString) {
final bytes = utf8.encode(vCardString);
final vCardData = utf8.decode(bytes);
final vCard = VCard.fromFormattedString(vCardData);
nameController.text = vCard.formattedName?.value ?? '';
emailController.text = vCard.email?.value ?? '';
}
@override
void dispose() {
controller?.dispose();
super.dispose();
}
}
void main() {
runApp(MaterialApp(
home: QRScanPage(),
));
}
I noticed that you changed the function fromBytes to fromFormattedString, which is the correct approach to parse vCard data from a formatted string. Your updated code appears to be correct for parsing vCard data successfully.
英文:
I'm encountering an error in my Flutter code where I'm trying to parse a vCard using the vcard package. However, I'm getting the error message "The method 'fromBytes' isn't defined for the type 'VCard'". Here's the relevant code
import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:qr_code_scanner/qr_code_scanner.dart';
import 'package:vcard/vcard.dart';
class QRScanPage extends StatefulWidget {
@override
_QRScanPageState createState() => _QRScanPageState();
}
class _QRScanPageState extends State<QRScanPage> {
final GlobalKey qrKey = GlobalKey(debugLabel: 'QR');
Barcode? result;
QRViewController? controller;
TextEditingController nameController = TextEditingController();
TextEditingController emailController = TextEditingController();
@override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
children: <Widget>[
Expanded(
flex: 5,
child: QRView(
key: qrKey,
onQRViewCreated: _onQRViewCreated,
),
),
Expanded(
flex: 1,
child: Center(
child: Column(
children: [
TextField(
controller: nameController,
decoration: InputDecoration(
labelText: 'Name',
),
),
TextField(
controller: emailController,
decoration: InputDecoration(
labelText: 'Email',
),
),
],
),
),
)
],
),
);
}
void _onQRViewCreated(QRViewController controller) {
this.controller = controller;
controller.scannedDataStream.listen((scanData) {
setState(() {
result = scanData;
parseVCard(result!.code);
});
});
}
void parseVCard(String vCardString) {
final vCard = VCard.fromBytes(utf8.encode(vCardString));
nameController.text = vCard.formattedName.value ?? '';
emailController.text = vCard.email.value ?? '';
}
@override
void dispose() {
controller?.dispose();
super.dispose();
}
}
void main() {
runApp(MaterialApp(
home: QRScanPage(),
));
}
I have already added the vcard package to my pubspec.yaml file.
name: datacollector
description: A new Flutter project.
# The following line prevents the package from being accidentally published to
# pub.dev using `flutter pub publish`. This is preferred for private packages.
publish_to: 'none' # Remove this line if you wish to publish to pub.dev
# The following defines the version and build number for your application.
# A version number is three numbers separated by dots, like 1.2.43
# followed by an optional build number separated by a +.
# Both the version and the builder number may be overridden in flutter
# build by specifying --build-name and --build-number, respectively.
# In Android, build-name is used as versionName while build-number used as versionCode.
# Read more about Android versioning at https://developer.android.com/studio/publish/versioning
# In iOS, build-name is used as CFBundleShortVersionString while build-number is used as CFBundleVersion.
# Read more about iOS versioning at
# https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
# In Windows, build-name is used as the major, minor, and patch parts
# of the product and file versions while build-number is used as the build suffix.
version: 1.0.0+1
environment:
sdk: '>=2.18.5 <3.0.0'
# Dependencies specify other packages that your package needs in order to work.
# To automatically upgrade your package dependencies to the latest versions
# consider running `flutter pub upgrade --major-versions`. Alternatively,
# dependencies can be manually updated by changing the version numbers below to
# the latest version available on pub.dev. To see which dependencies have newer
# versions available, run `flutter pub outdated`.
dependencies:
flutter:
sdk: flutter
http: ^0.13.4
# The following adds the Cupertino Icons font to your application.
# Use with the CupertinoIcons class for iOS style icons.
cupertino_icons: ^1.0.5
qr_code_scanner: ^0.4.0
vcard: any
vcard_parser: ^0.1.0
dev_dependencies:
flutter_test:
sdk: flutter
# The "flutter_lints" package below contains a set of recommended lints to
# encourage good coding practices. The lint set provided by the package is
# activated in the `analysis_options.yaml` file located at the root of your
# package. See that file for information about deactivating specific lint
# rules and activating additional ones.
flutter_lints: ^2.0.0
# For information on the generic Dart part of this file, see the
# following page: https://dart.dev/tools/pub/pubspec
# The following section is specific to Flutter packages.
flutter:
# The following line ensures that the Material Icons font is
# included with your application, so that you can use the icons in
# the material Icons class.
uses-material-design: true
assets:
- assets/
# To add assets to your application, add an assets section, like this:
# assets:
# - images/a_dot_burr.jpeg
# - images/a_dot_ham.jpeg
# An image asset can refer to one or more resolution-specific "variants", see
# https://flutter.dev/assets-and-images/#resolution-aware
# For details regarding adding assets from package dependencies, see
# https://flutter.dev/assets-and-images/#from-packages
# To add custom fonts to your application, add a fonts section here,
# in this "flutter" section. Each entry in this list should have a
# "family" key with the font family name, and a "fonts" key with a
# list giving the asset and other descriptors for the font. For
# example:
# fonts:
# - family: Schyler
# fonts:
# - asset: fonts/Schyler-Regular.ttf
# - asset: fonts/Schyler-Italic.ttf
# style: italic
# - family: Trajan Pro
# fonts:
# - asset: fonts/TrajanPro.ttf
# - asset: fonts/TrajanPro_Bold.ttf
# weight: 700
#
# For details regarding fonts from package dependencies,
# see https://flutter.dev/custom-fonts/#from-packages
How can I resolve this error and successfully parse the vCard data from a byte array? Any help would be appreciated. Thank you!
I tried to change the function fromBytes to another function called fromFormattedString this is my code after changing
import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:qr_code_scanner/qr_code_scanner.dart';
import 'package:vcard/vcard.dart';
class QRScanPage extends StatefulWidget {
@override
_QRScanPageState createState() => _QRScanPageState();
}
class _QRScanPageState extends State<QRScanPage> {
final GlobalKey qrKey = GlobalKey(debugLabel: 'QR');
Barcode? result;
QRViewController? controller;
TextEditingController nameController = TextEditingController();
TextEditingController emailController = TextEditingController();
@override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
children: <Widget>[
Expanded(
flex: 5,
child: QRView(
key: qrKey,
onQRViewCreated: _onQRViewCreated,
),
),
Expanded(
flex: 1,
child: Center(
child: Column(
children: [
TextField(
controller: nameController,
decoration: InputDecoration(
labelText: 'Name',
),
),
TextField(
controller: emailController,
decoration: InputDecoration(
labelText: 'Email',
),
),
],
),
),
)
],
),
);
}
void _onQRViewCreated(QRViewController controller) {
this.controller = controller;
controller.scannedDataStream.listen((scanData) {
setState(() {
result = scanData;
parseVCard(result!.code);
});
});
}
void parseVCard(String vCardString) {
final bytes = utf8.encode(vCardString);
final vCardData = utf8.decode(bytes);
final vCard = VCard.fromFormattedString(vCardData);
nameController.text = vCard.formattedName.value ?? '';
emailController.text = vCard.email.value ?? '';
}
@override
void dispose() {
controller?.dispose();
super.dispose();
}
}
void main() {
runApp(MaterialApp(
home: QRScanPage(),
));
}
答案1
得分: 1
由于您的pubspec.yaml文件指示您正在使用simple_vcard_parser包,示例显示您应该能够通过调用VCard(string)
来创建一个VCard实例。
您应该能够将您的parseVCard方法简化为:
void parseVCard(String vCardString) {
final vCard = VCard(vCardString);
}
您可能需要添加导入语句:
import 'package:simple_vcard_parser/simple_vcard_parser.dart';
并删除现有的导入语句:
import 'package:vcard/vcard.dart';
英文:
Since your pubspec.yaml file indicates you are using simple_vcard_parser package, the example shows you should be able to create a VCard instance by calling VCard(string)
.
You should be able to change your parseVCard method to simply be:
void parseVCard(String vCardString) {
final vCard = VCard(vCardString);
}
You may need to add the import statement
import 'package:simple_vcard_parser/simple_vcard_parser.dart';
and remove the existing import of
import 'package:vcard/vcard.dart';
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