node.js - 如何使用云功能正确连接到 MongoDB？

Question

我只想为每个运行 Cloud Functions 的实例连接一次我的 Atlas 集群。

这是我的实例代码:

const MongoClient = require("mongodb").MongoClient;

const client = new MongoClient("myUrl", {
  useNewUrlParser: true,
  useUnifiedTopology: true,
});

exports.myHttpMethod = functions.region("europe-west1").runWith({
  memory: "128MB",
  timeoutSeconds: 20,
}).https.onCall((data, context) => {
  console.log("Data is: ", data);
  client.connect(() => {
    const testCollection = client.db("myDB").collection("test");
    testCollection.insertOne(data);
  });
});

而且我想避免在每个函数调用中使用 client.connect()，这似乎真的太多了。

我想做这样的事情:

const MongoClient = require("mongodb").MongoClient;

const client = await MongoClient.connect("myUrl", {
  useNewUrlParser: true,
  useUnifiedTopology: true,
});

const db = client.db("myDB");

exports.myHttpMethod = functions.region("europe-west1").runWith({
  memory: "128MB",
  timeoutSeconds: 20,
}).https.onCall((data, context) => {
  console.log("Data is: ", data);
  const testCollection = db.collection("test");
  testCollection.insertOne(data);
});

但我不能这样等待。
在我的 AWS Lambda 函数(在 python 中运行)中，我没有这个问题，每个实例我只能连接一次，所以我想有一个等价物，但我不太了解 JS/Node JS。

Answer 1

您可以将数据库客户端存储为 global variable .从文档中，

Cloud Functions often recycles the execution environment of a previous invocation. If you declare a variable in global scope, its value can be reused in subsequent invocations without having to be recomputed.

尝试重构代码，如下所示:

import * as functions from "firebase-functions";

import { MongoClient } from "mongodb"; 

let client: MongoClient | null;

const getClient = async () => {
  if (!client) {
    const mClient = new MongoClient("[MONGODB_URI]", {});
    client = await mClient.connect();
    functions.logger.log("Connected to MongoDB");
  } else {
    functions.logger.log("Using existing MongoDB connection");
  }
  functions.logger.log("Returning client");
  return client;
};

export const helloWorld = functions.https.onRequest(
  async (request, response) => {
    const db = (await getClient()).db("[DATABASE]");
    const result = await db.collection("[COLLECTION]").findOne({});
    response.send("Hello from Firebase!");
  }
);

这应该重用该实例的连接。