Lambda不会写入mongodb，但我可以在本地写入它

我使用的是通过服务器less部署到aws的aws lambda，并使用连接字符串写入mongodb。当在本地调用lambda时，所有这些都有效，并且我检查了一下，看我正在本地写入到lambda的数据的格式与我正在写入实时lambda的格式相同，而且确实如此。我不知道怎么了，因为我没有收到错误。

    "use strict";
    module.exports.addNewMenuItem = async event => {
        var MongoClient = require('mongodb').MongoClient;
        const options = {
            socketTimeoutMS: 30000,
            keepAlive: true,
            reconnectTries: 30000,
            useUnifiedTopology: true  , 
            useNewUrlParser: true 
        };
        ;

        console.log(process.env.MONGO_CONNECTION_STRING)
        console.log("eb", event.body)
        const { coffee_type, coffee_subtype, business_id } = event.body
        const client = new MongoClient(process.env.MONGO_CONNECTION_STRING, options);
        await client.connect(clientConnectError => {
            if (clientConnectError) {
                console.log("client connection error", clientConnectError)
            }

            client.db("Coffee2Go").collection("MenuItems").insertOne({ coffee_type, coffee_subtype, business_id }, function (writeError, result) {
                if (writeError) {
                    console.log("db error", writeError)
                }

                console.log("added the new menu item successfully")
            });
        });

        return {
            "body": "menu item added successfully",
            "headers": {
                "Access-Control-Allow-Origin": "*"
            },
            "statusCode": 200
        };
    };

如您所见，您的函数仅需要6.78毫秒即可完成，这意味着该函数没有等待查询完成，它只是立即返回一个对象。按下return时该功能将停止。

在您的本地端，当函数获得return时，Mongodb查询仍在运行。但是它在lambda端不起作用，当功能停止时，它将停止所有进程。

主要原因是您将async/await语法与callback的MongoClient语法混合。

await client.connect(clientConnectError => { // does not make sense 

作为Mongodb document，您可以将其方法用作Promises。

"use strict";
module.exports.addNewMenuItem = async event => {
  var MongoClient = require('mongodb').MongoClient;
  const options = {
    socketTimeoutMS: 30000,
    keepAlive: true,
    reconnectTries: 30000,
    useUnifiedTopology: true,
    useNewUrlParser: true
  };
  ;

  console.log(process.env.MONGO_CONNECTION_STRING)
  console.log("eb", event.body)
  const { coffee_type, coffee_subtype, business_id } = event.body
  const client = new MongoClient(process.env.MONGO_CONNECTION_STRING, options);

  try {
    await client.connect() // return Promise if no callback passed
    await client.db("Coffee2Go").collection("MenuItems").insertOne({ coffee_type, coffee_subtype, business_id })
    console.log("added the new menu item successfully")
  } catch(err) {
    console.log("db error", writeError)
    // As your original logic. The error will not effect to result of the function.
    // But, I think this is not a good flow, you need tell to your client that process get back an error in this case
    return {
      "body": JSON.stringify({
        message: "Insert item error",
        error: err.message
      }),
      "headers": {
        "Access-Control-Allow-Origin": "*"
      },
      "statusCode": 500 // instead of 200 - success
    };
  }

  return {
    "body": "menu item added successfully",
    "headers": {
      "Access-Control-Allow-Origin": "*"
    },
    "statusCode": 200
  };
};