Why am I still getting MongoExpiredSessionError even though I'm parsing the json in my azure function?

Question

With regards to my Azure function, I cannot for the life of me figure out why I'm getting MongoExpiredSessionError: Cannot use a session that has ended error when trying to do an extremely simple insertion. I've tried JSON.parse(result); and JSON.stringify(result); but still getting the same error.

I've also tried removing the finally block, tried adding await in front of collection() but still getting the same error. I've pretty much done all the I can that I've found on the web to troubleshoot but to no avail.

What am I doing wrong?

Here's my code:

const mongo = require('mongodb');
const MongoClient = require('mongodb').MongoClient;
const uri = "myUri"

module.exports = async function (context, req) {
    const client = await MongoClient.connect(uri, {useNewUrlParser:true}).catch(err => {context.log(err); });

    let result = null;
    let callerEntityProfile = req.body.CallerEntityProfile;
    let packIdInput = callerEntityProfile.Entity.PackIdInput;
    let userId = callerEntityProfile.Entity.UserID;

    try {
        const db = await client.db("myDB");
        let collection = await db.collection("myCollection");
        let query = { userId : userId };
        result = await collection.findOne(query);

        let insertPack = {
          "PackId" : packIdInput
        };

        result.packsOwned.push(insertPack);

        JSON.parse(result);

        collection.insertOne(result, function(err, r) {
          console.log('inside insertOne')
          console.log(err); // this is where it's showing the error message
        });

    }
    catch (err) {
        context.log(err);
    }
    finally {
        client.close();
    }

   
}

score 0 · Answer 1 · answered May 05 '22 at 05:53

Since it does not wait until the end of the asynchronous function, the close action is faster than insertMany action. You can try the following:

const DB = client.db(databasename);

const myAsyncFunction = async() => {
  const collection = await DB.collection(nameofcollection); // do this INSIDE async function

  await collection.insertMany(details); // similarly inside async
};

client.close();

Alternatively, you may try something like this:

client.connect(err => {
  if(err) return console.log(err);

  client.db(databasename).collection(nameofcollection)
      .then(collection => collection.insertMany(details))
      .then(() => client.close());
});

You can refer to these similar SO threads -
How to fix MongoError: Cannot use a session that has ended
MongoError: Cannot use a session that has ended
Node js throws MongoError
MongoError

Why am I still getting MongoExpiredSessionError even though I'm parsing the json in my azure function?

1 Answers1