错误:在Flutter中,类型’VCard’未定义方法’fromBytes’。

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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 &#39;dart:convert&#39;;
import &#39;package:flutter/material.dart&#39;;
import &#39;package:qr_code_scanner/qr_code_scanner.dart&#39;;
import &#39;package:vcard/vcard.dart&#39;;
class QRScanPage extends StatefulWidget {
@override
_QRScanPageState createState() =&gt; _QRScanPageState();
}
class _QRScanPageState extends State&lt;QRScanPage&gt; {
final GlobalKey qrKey = GlobalKey(debugLabel: &#39;QR&#39;);
Barcode? result;
QRViewController? controller;
TextEditingController nameController = TextEditingController();
TextEditingController emailController = TextEditingController();
@override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
children: &lt;Widget&gt;[
Expanded(
flex: 5,
child: QRView(
key: qrKey,
onQRViewCreated: _onQRViewCreated,
),
),
Expanded(
flex: 1,
child: Center(
child: Column(
children: [
TextField(
controller: nameController,
decoration: InputDecoration(
labelText: &#39;Name&#39;,
),
),
TextField(
controller: emailController,
decoration: InputDecoration(
labelText: &#39;Email&#39;,
),
),
],
),
),
)
],
),
);
}
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 ?? &#39;&#39;;
emailController.text = vCard.email.value ?? &#39;&#39;;
}
@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: &#39;none&#39; # 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: &#39;&gt;=2.18.5 &lt;3.0.0&#39;
# 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 &quot;flutter_lints&quot; 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 &quot;variants&quot;, 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 &quot;flutter&quot; section. Each entry in this list should have a
# &quot;family&quot; key with the font family name, and a &quot;fonts&quot; 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 &#39;dart:convert&#39;;
import &#39;package:flutter/material.dart&#39;;
import &#39;package:qr_code_scanner/qr_code_scanner.dart&#39;;
import &#39;package:vcard/vcard.dart&#39;;
class QRScanPage extends StatefulWidget {
@override
_QRScanPageState createState() =&gt; _QRScanPageState();
}
class _QRScanPageState extends State&lt;QRScanPage&gt; {
final GlobalKey qrKey = GlobalKey(debugLabel: &#39;QR&#39;);
Barcode? result;
QRViewController? controller;
TextEditingController nameController = TextEditingController();
TextEditingController emailController = TextEditingController();
@override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
children: &lt;Widget&gt;[
Expanded(
flex: 5,
child: QRView(
key: qrKey,
onQRViewCreated: _onQRViewCreated,
),
),
Expanded(
flex: 1,
child: Center(
child: Column(
children: [
TextField(
controller: nameController,
decoration: InputDecoration(
labelText: &#39;Name&#39;,
),
),
TextField(
controller: emailController,
decoration: InputDecoration(
labelText: &#39;Email&#39;,
),
),
],
),
),
)
],
),
);
}
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 ?? &#39;&#39;;
emailController.text = vCard.email.value ?? &#39;&#39;;
}
@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 &#39;package:simple_vcard_parser/simple_vcard_parser.dart&#39;;
and remove the existing import of
import &#39;package:vcard/vcard.dart&#39;;

huangapple
  • 本文由 发表于 2023年7月11日 04:21:33
  • 转载请务必保留本文链接:https://go.coder-hub.com/76657079.html
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