[英]flutter: LateInitializationError: Field 'name' has not been initialized
[英]Flutter Unhandled Exception: LateInitializationError: Local 'name' has not been initialized
我有一个 flutter 应用程序,它试图比较两组应用程序版本号,第一个版本号使用 hive 在本地存储,第二个版本号来自 firestore。 我可以从 firestore 获取数据,但我无法比较两者,因为从 firestore 获取数据需要一段时间。
这是从 Firestore 获取数据的代码
late final Box detailsBox;
@override
void initState() {
super.initState();
detailsBox = Hive.box('appDetails');
updateApplication();
}
CollectionReference groceries =
FirebaseFirestore.instance.collection('updates');
late String? name;
late String? version;
late String? downloadUrl;
getData() {
groceries.orderBy('name').snapshots().listen((gets) {
try {
for (var gettt in gets.docs) {
name = gettt['name'] ?? 'null';
version = gettt['version'] ?? 'null';
downloadUrl = gettt['download url'] ?? 'null';
debugPrint('name: $name');
debugPrint('version: $version');
debugPrint('downloadUrl: $downloadUrl');
_addInfo(name!, version!, downloadUrl!); }
} catch (e) {
print(e);
}
});
}
这是比较版本号的代码
int getExtendedVersionNumber(String version) {
List versionCells = version.split('.');
if (kDebugMode) {
print(versionCells);
}
versionCells = versionCells.map((i) => int.parse(i)).toList();
return versionCells[0] * 10000 + versionCells[1] * 100 + versionCells[2];
}
Future compareData() async {
await getData();
String localName = detailsBox.get('name');
String localVersion = detailsBox.get('version');
String downloadLink = detailsBox.get('downloadLink');
debugPrint(
'Info retrieved from detailsBox below:\n $localName\n ($localVersion) \n $downloadLink');
debugPrint(
'Info retrieved from firebase below:\n $name\n ($version) \n $downloadUrl');
int version1Number = getExtendedVersionNumber(localVersion); // return 102003
int version2Number = getExtendedVersionNumber(version!); // return 102003
if (kDebugMode) {
print(version1Number == version2Number);
print(version1Number > version2Number);
print(version1Number < version2Number);
}
if (version2Number > version1Number) {
debugPrint('true');
debugPrint(downloadUrl);
}
}
当它到达这一点时debugPrint( 'Info retrieved from firebase below:\n $name\n ($version) \n $downloadUrl');
我收到后期初始化错误[ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled Exception: LateInitializationError: Field 'name' has not been initialized.
如何修改代码,以便在运行时我可以考虑获取数据所需的时间,然后最终比较版本
只是改变
late String? name;
至
String? name;
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