Firebase第二代云函数报错：TypeError: Cannot read properties of undefined (reading 'value')

从Firebase第一代云函数切换到第二代时出现报错，相关代码、错误信息及package.json配置如下：

原代码 #

const {onDocumentCreated} = require("firebase-functions/v2/firestore");
exports.totalGroup = onDocumentCreated(
  {region: "asia-southeast2"}, "tallyscan/{id}", async (event)=>{
    console.log("get event data");
    const snapshot = event.data();
    const id = event.params.id;
    console.log(snapshot);
    console.log(id);
  });

报错信息 #

TypeError: Cannot read properties of undefined (reading 'value')
at func (/workspace/node_modules/firebase-functions/lib/v2/providers/firestore.js:297:115)
at /layers/google.nodejs.functions-framework/functions-framework/node_modules/@google-cloud/functions-framework/build/src/function_wrappers.js:113:25
at process.processTicksAndRejections (node:internal/process/task_queues:95:5)

package.json配置 #

{
  "name": "functions",
  "description": "Cloud Functions for Firebase",
  "scripts": {
    "lint": "eslint .",
    "serve": "firebase emulators:start --only functions",
    "shell": "firebase functions:shell",
    "start": "npm run shell",
    "deploy": "firebase deploy --only functions",
    "logs": "firebase functions:log"
  },
  "engines": {
    "node": "18"
  },
  "main": "index.js",
  "dependencies": {
    "exceljs": "^4.4.0",
    "firebase-admin": "^12.1.0",
    "firebase-functions": "^5.0.1"
  },
  "devDependencies": {
    "eslint": "^8.15.0",
    "eslint-config-google": "^0.14.0",
    "firebase-functions-test": "^3.1.0"
  },
  "private": true
}

解决方案 #

报错原因是第二代Firestore触发器的参数格式错误：第二代API要求将区域配置和文档路径合并到同一个配置对象中，而非分开传递。

修正后的代码：

const {onDocumentCreated} = require("firebase-functions/v2/firestore");
exports.totalGroup = onDocumentCreated(
  {
    region: "asia-southeast2",
    document: "tallyscan/{id}"
  }, 
  async (event)=>{
    console.log("get event data");
    const snapshot = event.data();
    const id = event.params.id;
    console.log(snapshot);
    console.log(id);
  });

说明：第二代云函数的onDocumentCreated仅接受两个参数——包含所有配置项的对象，以及触发时执行的回调函数。文档路径需要放在配置对象的document字段中，之前分开传递参数的写法会导致触发器内部无法正确解析路径，从而抛出Cannot read properties of undefined (reading 'value')错误。

内容的提问来源于stack exchange，提问作者marendra