pubspec.yaml 没有下限 SDK 约束

Question

我正在参加 MDC101 颤振代码实验室。我按照说明从 git 存储库中克隆了启动项目，但在克隆完成后，我执行了 flutter pub get，它给了我以下错误。

pubspec.yaml has no lower-bound SDK constraint.
You should edit pubspec.yaml to contain an SDK constraint:
environment:
  sdk: '>=2.10.0 <3.0.0'

Answer 1

根据错误说明，我在 pubspec.yaml

中添加了以下内容

environment:
  sdk: '>=2.10.0 <3.0.0'

然后我执行了flutter pub get，现在一切正常。

Answer 2

使用命令行检查你的 flutter 频道：

flutter channel

如果它在主频道然后切换到稳定频道：

flutter channel stable

Answer 3

如果您在 pubspec.yaml 文件包含正确的 sdk 行时仍收到此错误，请务必检查主文件夹中的子文件夹。当从 font_awesome_flutter 包中执行 flutter packages get 时，注意到会发生这种情况。原因是即使主要 pubspec.yaml 包含正确的行，但有一个令人不快的 example/pubspec.yaml。将行添加到该文件：

environment:
  sdk: ">=2.7.0 <3.0.0"

Referenced issue.

Answer 4

As of Dart 2.12, omitting the SDK constraint is an error. When the pubspec has no SDK constraint, pub get fails with a message like the following:

pubspec.yaml has no lower-bound SDK constraint.
You should edit pubspec.yaml to contain an SDK constraint:
(...)

For example, the following constraint says that this package works with any Dart SDK that’s version 2.10.0 or higher:

environment:
  sdk: '>=2.10.0 <3.0.0'

有关详细信息，您可以查看 docs

pubspec.yaml 没有下限 SDK 约束

pubspec.yaml has no lower-bound SDK constraint

sdk

lower-bound

flutter

flutter-web

flutter-pub