flutter - 生成器无法定位尚未迁移到空安全的库

Question

尝试以下命令时会出现此问题:flutter pub run build_runner build --delete-conflicting-outputs错误信息:

[SEVERE] json_serializable:json_serializable on lib/models/shipping_address/shipping_address.dart:

Generator cannot target libraries that have not been migrated to null-safety.
package:deals_and_delivery/models/shipping_address/shipping_address.dart:6:7
  ╷
6 │ class ShippingAddress {
  │       ^^^^^^^^^^^^^^^
  ╵
[INFO] Running build completed, took 3.6s

[INFO] Caching finalized dependency graph...
[INFO] Caching finalized dependency graph completed, took 49ms

[SEVERE] Failed after 3.7s
pub finished with exit code 1

pubspec.yaml:

dependencies:
  json_annotation: ^4.0.0
  flutter:
    sdk: flutter
...
dev_dependencies:
  build_runner: ^1.11.5
  json_serializable: ^4.0.2
  flutter_test:
    sdk: flutter

这些是当前的 flutter 和 dart 版本:

[√] Flutter (Channel stable, 2.0.0, on Microsoft Windows [Version
> 10.0.19042.844], locale en-US)
>     • Flutter version 2.0.0 at C:\flutter
>     • Framework revision 60bd88df91 (22 hours ago), 2021-03-03 09:13:17 -0800
>     • Engine revision 40441def69
>     • Dart version 2.12.0

我被困在这一点上，如何解决这个问题。

Answer 1

我发现 json_serializable >=4.0.0取决于 json_annotation >=4.0.0 <4.1.0和 json_annotation: ^4.0.0包括 Null Safety但是 json_serializable: ^4.0.2 不 ，所以错误正在发生。
所以我降级了两个包:

json_annotation: 3.1.1

和

json_serializable: 3.5.1

他们再次正常工作。