当我尝试跑步时
time_str = "2019-07-30T00:00:00.000-05:00"
time_str = time_str[0:-3]+time_str[-2:]
我明白了：
dart migrate
但是当我运行 flutter pub 时会过时
Bad state: Error: package has unmigrated dependencies.
Before migrating your package, we recommend ensuring that every library it
imports (either directly or indirectly) has been migrated to null safety, so
that you will be able to run your unit tests in sound null checking mode. You
are currently importing the following non-null-safe libraries:
package:firebase_database/firebase_database.dart
package:firebase_database/src/utils/push_id_generator.dart
在我的 pubscpec.yaml 中
flutter pub outdated --mode=null-safety
Showing dependencies that are currently not opted in to null-safety.
[✗] indicates versions without null safety support.
[✓] indicates versions opting in to null safety.
All your dependencies declare support for null-safety.