Firebase 云消息生成错误

Question

每当写入文档字段时，我都会尝试触发推送通知。由于我是 node.js 的新手，我很难调试这个看似简单的功能。这是我的代码：

// The Cloud Functions for Firebase SDK to create Cloud Functions and setup triggers.
const functions = require('firebase-functions');

// The Firebase Admin SDK to access the Firebase Realtime Database.
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);

exports.sendNotification = functions.firestore.document("Customer_Data/{userEmail}/Placed_Orders/{orderId}/status").onWrite(event => {
  const userEmail = event.params.userEmail;

  const message = "Your meal will be delivered in 2 hours";
  const title = "Eat Away";

  const toUser = admin.firestore().collection("Customer_Data").doc(userEmail).get();

  return admin.firestore().collection("Customer_Data").doc({userEmail}).get().then(queryResult => {
    const tokenId = queryResult.data().tokenId;

    const notificationContent = {
      notification: {
        title: title,
        body: message,
      }
    }
  });

  return admin.messaging().sendToDevice(tokenId , notificationContent).then(function(response) {
    console.log("Message sent successfully");
  }).catch(function(error){
    console.log("Error sending message:", error);
  });

});

这是我在终端收到的错误：

 53:11  warning  Avoid nesting promises                      promise/no-nesting
  53:11  warning  Avoid nesting promises                      promise/no-nesting
  53:77  warning  Unexpected function expression              prefer-arrow-callback
  53:77  error    Each then() should return a value or throw  promise/always-return
  55:13  warning  Unexpected function expression              prefer-arrow-callback

✖ 5 problems (1 error, 4 warnings)
  0 errors and 2 warnings potentially fixable with the `--fix` option.

npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! functions@ lint: `eslint .`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the functions@ lint script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

Error: functions predeploy error: Command terminated with non-zero exit code1

我没有使用承诺，因为我没有看到它的意义。但同时我尝试了它并没有帮助。

Answer 1

没有看到承诺的意义通常是更多了解它们的理由，而不是不使用它们。

您现在编写代码的方式意味着它的一部分永远不会运行。这与 Promise 没有任何关系，只是因为代码的主要流程中有两个 return 语句：

exports.sendNotification = functions.firestore.document("Customer_Data/{userEmail}/Placed_Orders/{orderId}/status").onWrite(event => {
  ...
  return admin.firestore().collection("Customer_Data").doc({userEmail}).get().then(queryResult => {
    ...
  });

  // Nothing below this line ever executes
  return admin.messaging().sendToDevice(tokenId , notificationContent).then(function(response) {
    console.log("Message sent successfully");
  }).catch(function(error){
    console.log("Error sending message:", error);
  });
});

在这种情况下，您需要 Firestore 的结果来发送 FCM 消息，这意味着您需要等待 Firestore 承诺解决（使用 then() 或 await），然后再调用 FCM：

exports.sendNotification = functions.firestore.document("Customer_Data/{userEmail}/Placed_Orders/{orderId}/status").onWrite(event => {
  const userEmail = event.params.userEmail;

  const message = "Your meal will be delivered in 2 hours";
  const title = "Eat Away";

  const toUser = admin.firestore().collection("Customer_Data").doc(userEmail).get();

  return admin.firestore().collection("Customer_Data").doc({userEmail}).get().then(queryResult => {
    const tokenId = queryResult.data().tokenId;

    notificationContent = {
      notification: {
        title: title,
        body: message,
      }
    }

    return admin.messaging().sendToDevice(tokenId , notificationContent);
  })
});