RealmJS TypeError: Cannot read property 'Realm' of undefined

Question

这是我在使用 React Native 应用程序时遇到的 RealmJS 问题。我花了四天多的时间试图调试出了什么问题（我已经构建了应用程序的重要部分，认为它会在较新的版本中得到修补）。希望这对某人有所帮助。

我正在尝试调试我的 React Native 应用程序，但由于 RealmJS 而无法调试。当我运行我的模拟器或设备（iOS 或 Android）时，该应用程序运行良好。但是，打开远程调试，应用程序只会在启动时挂起。我收到以下错误以及空白屏幕：

TypeError: Cannot read property 'Realm' of undefined
   reactConsoleErrorHandler  @  ExceptionsManager.js:179
   n  @  backend.js:32
   reportException  @  ExceptionsManager.js:104
   handleException  @  ExceptionsManager.js:171
   handleError  @  setUpErrorHandling.js:24
   reportFatalError  @  error-guard.js:49
   guardedLoadModule  @  require.js:204
   metroRequire  @  require.js:128
   (anonymous)  @  index.js:118
   executeApplicationScript  @  RNDebuggerWorker.js:2
   (anonymous)  @  RNDebuggerWorker.js:2

我试过重置缓存（watchman、react-native、pods 等）、清理构建文件夹，甚至重启我的机器，但似乎没有任何效果。在一个新项目中安装 Realm 表明它工作得很好，但我不想重做我的整个项目。我做错了什么？

设置（npx react-native info）：

System:
    OS: macOS 10.15.5
    CPU: (12) x64 Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
    Memory: 230.89 MB / 16.00 GB
    Shell: 5.7.1 - /bin/zsh
  Binaries:
    Node: 14.12.0 - /usr/local/bin/node
    Yarn: 1.22.4 - /usr/local/bin/yarn
    npm: 6.14.8 - ~/Projects/MyApp/node_modules/.bin/npm
    Watchman: 4.9.0 - /usr/local/bin/watchman
  Managers:
    CocoaPods: 1.9.3 - /usr/local/bin/pod
  SDKs:
    iOS SDK:
      Platforms: iOS 13.6, DriverKit 19.0, macOS 10.15, tvOS 13.4, watchOS 6.2
    Android SDK: Not Found
  IDEs:
    Android Studio: 4.0 AI-193.6911.18.40.6626763
    Xcode: 11.6/11E708 - /usr/bin/xcodebuild
  Languages:
    Java: 14.0.2 - /usr/bin/javac
    Python: 2.7.16 - /usr/bin/python
  npmPackages:
    @react-native-community/cli: ^4.13.0 => 4.13.0 
    react: 16.13.1 => 16.13.1 
    react-native: 0.63.3 => 0.63.3 
    react-native-macos: Not Found
  npmGlobalPackages:
    *react-native*: Not Found

Answer 1

我花了很多时间试图解决这个问题。将我的项目拼凑起来后 bit-by-bit，我发现了问题：babel-plugin-module-resolver。

为了创建自定义路径别名（即 "@components/" -> "./src/components/"），我必须安装 babel-plugin-module-resolver 作为开发依赖项。

当我像这样设置插件时出现了问题：

// babel.config.js
module.exports = {
    presets: ["module:metro-react-native-babel-preset"],
    plugins: [
        [
            "module-resolver",
            {
                root: ["."],
                cwd: "packagejson",
                extensions: [
                    ".ts",
                    ".tsx",
                    ".js",
                    ".jsx",
                    ".ios.js",
                    ".android.js",
                    ".ios.ts",
                    ".android.ts",
                    ".ios.tsx",
                    ".android.tsx",
                ],
                alias: {
                    "@components": "./src/components",
                },
            },
        ],
    ],
};

解决方案是将 cwd 从 packagejson 更改为 babelrc。

// babel.config.js
module.exports = {
    presets: ["module:metro-react-native-babel-preset"],
    plugins: [
        [
            "module-resolver",
            {
                ...

                cwd: "babelrc", // <-- here

                ...

在那之后，我可以运行正确调试！

Note: At the time of this answer there is another error that appears with the debugger for Realm 10.0.1 and RN 0.63.3, but this is an actual bug as opposed to a user error.

RealmJS TypeError: Cannot read property 'Realm' of undefined

RealmJS TypeError: Cannot read property 'Realm' of undefined

remote-debugging

realm

typescript

react-native