Question

我的应用无法连接到 Firebase 实时数据库。当我运行下面的代码时，总是会打印日志“未连接”。此外，代码 ref.once('value', snapshot => ...) 不返回任何结果，也不返回错误（永远挂断）。请告诉我我的代码有什么问题，以及如何解决它。谢谢。

const firebase = require('firebase/app');
require('firebase/auth');
require('firebase/database');

const config = {
  apiKey: "...",
  authDomain: "...",
  databaseURL: "...",
  projectId: "...",
  storageBucket: "...",
  messagingSenderId: "...",
  appId: "..."
};
firebase.initializeApp(config);

function test() {
  //Test connnection (https://firebase.google.com/docs/database/web/offline-capabilities#section-connection-state)
  const connectedRef = firebase.database().ref('.info/connected');
  connectedRef.on('value', (snap) => {
    if (snap.val() === true) {
      console.log('connected');
    } else {
      console.error('not connected');
    }
  });

  //Test retrieve data.
  const ref = firebase.database().ref('/');
  ref.once('value', snapshot => {
    const data = snapshot.val();
    console.log(data);
  }).catch(error => {
    console.error(error);
  })
}
test();

PS：这不是Cannot connect to Firebase Realtime Database

的重复

Answer 1

该问题可能与您的防火墙设置或认证问题有关。例如，如果您的计算机使用自签名证书，Node.js 可能会抛出异常 <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>CFBundleDevelopmentRegion</key> <string>$(DEVELOPMENT_LANGUAGE)</string> <key>CFBundleExecutable</key> <string>$(EXECUTABLE_NAME)</string> <key>CFBundleIdentifier</key> <string>$(PRODUCT_BUNDLE_IDENTIFIER)</string> <key>CFBundleInfoDictionaryVersion</key> <string>6.0</string> <key>CFBundleName</key> <string>muslim_2b</string> <key>CFBundlePackageType</key> <string>APPL</string> <key>CFBundleShortVersionString</key> <string>$(FLUTTER_BUILD_NAME)</string> <key>CFBundleSignature</key> <string>????</string> <key>CFBundleVersion</key> <string>$(FLUTTER_BUILD_NUMBER)</string> <key>LSRequiresIPhoneOS</key> <true/> <key>UILaunchStoryboardName</key> <string>LaunchScreen</string> <key>UIMainStoryboardFile</key> <string>Main</string> <key>UISupportedInterfaceOrientations</key> <array> <string>UIInterfaceOrientationPortrait</string> <string>UIInterfaceOrientationLandscapeLeft</string> <string>UIInterfaceOrientationLandscapeRight</string> </array> <key>UISupportedInterfaceOrientations~ipad</key> <array> <string>UIInterfaceOrientationPortrait</string> <string>UIInterfaceOrientationPortraitUpsideDown</string> <string>UIInterfaceOrientationLandscapeLeft</string> <string>UIInterfaceOrientationLandscapeRight</string> </array> <key>UIViewControllerBasedStatusBarAppearance</key> <false/> <key>NSLocationWhenInUseUsageDescription</key> <string>This app needs access to location when open.</string> <key>NSLocationAlwaysUsageDescription</key> <string>This app needs access to location when in the background.</string> <key>NSLocationAlwaysAndWhenInUseUsageDescription</key> <string>This app needs access to location when open and in the background.</string> </dict> </plist>（令人惊讶的是 Firebase 客户端会默默地忽略它而不抛出任何异常，因此 try/catch 将不起作用）。您可以通过将 self signed certificate in certificate chain 添加到项目的第一行代码来检查它（请注意，它仅用于测试，因为如果在生产中使用该代码可能会导致安全问题）。

无法连接到 Firebase 实时数据库 (Node.js)

1 个答案: