用于推送通知的 Cloud Firebase 函数

Question

我正在尝试创建一个功能，一旦文档更改，推送通知就会发送到用户的移动设备。这是函数的代码：

 exports.userProfileChanged = functions.firestore.document('/agents/{agentId}').onWrite( (change, context) => {
    const userId = context.params.userId;

    console.log('A change has been made to user profile');

    // Get the user device token
    const getUserDeviceToken = db.document('/device/{agentId}').once('value');

    // The snapshot to the user's tokens.
    let deviceTokens;
    const results = Promise.all([getUserDeviceToken]);
    deviceTokens = results;

    if (deviceTokens == null) {
        return console.error('No device tokens found');
    }

    let title = "Changes have been made";
    let body = "changes have been made to your user profile";

    const payload = {
        notification: { title: title, body: body},
        token: snap.data().token,
        data: {click_action: 'FLUTTER_NOTIFICATION_CLICK' }
    };

    const response = admin.messaging().sendToDevice(deviceToken, payload);
    if (response.error) {
        console.error("Error sending message: ", response.error);
    } else {
        return console.log("Message sent successfully!");
    };
    
    return Promise.all(console.log('End of function'));
});

这是在 Firebase 的函数日志中发现的错误： 用户资料已更改 TypeError: db.document 不是函数

我做错了什么？

Answer 1

您需要先初始化数据库。这样一来，Firebase 就知道您指的是哪个数据库。

const admin = require('firebase-admin')
admin.initializeApp()

const db = admin.firestore()

exports.userProfileChanged = functions.firestore.document('/agents/{agentId}').onWrite( (change, context) => {
  // rest of your code
})

现在请注意，Firebase 仅允许您为所有功能调用一次 admin.initializeApp()。因此，将该进程移至另一个文件以在您的所有函数中重用可能是值得的。

// admin.js

const admin = require('firebase-admin')
admin.initializeApp()

exports.db = admin.firestore()
exports.admin = admin

// user-profile-changed.js

const { db } = require('./admin')

exports.userProfileChanged = functions.firestore.document('/agents/{agentId}').onWrite( (change, context) => {
  // rest of your code
})