Strings are encoded incorrectly in Atlas Triggered function

Inside an Atlas Triggered function, when I use JSON.stringify or console.log a property containing the curly quote character, e.g. , the output is changed to â.

What I did

Configure a Trigger function on a collection and log a property from a document, for example:

exports = async (changeEvent) => {
    const property = changeEvent && changeEvent.fullDocument &&
    console.log('the string', property)
    console.log('the json', JSON.stringify({ name: property }))

Create a document in the collection with a curly brace in the name property, e.g. { "name": "Test’s" }

View the log entry for the create.

What I expect to happen

The log entries should show the text using the curly quote, e.g. the output should be:

the string Test’s
the json {"name":"Test’s"}

What actually happens

The log entries show some other encoding mechanism:

the string Testâs
the json {"name":"Testâs"}

Additional details

This is not just a problem of the function log itself being encoded incorrectly: our trigger function pushes the JSON.stringify of the document to SQS, and the encoding shows the incorrect Testâs as well for the message on the SQS queue.

As of now, this behavior has been corrected, e.g. curly quotes now are left as curly quotes and so on.

I initially posted this to the MongoDB Jira board, before it was suggested by support that I post here.

Since I was able to isolate this behavior to the MongoDB Atlas triggered function, I would still like follow-up on what occurred on the MongoDB side, e.g. an incident report, and will comment here if I receive it.

This issue has come back again, and I have yet to hear any reply from a MongoDB representative.

For reference, the exact encoding transform is from to â\u0080\u0099

To be more clear here, the exact steps are:

  1. Create a document in the collection with a curly brace in the name property, e.g. { "name": "Test’s" }
  2. Look in the Atlas Trigger logs for the Function execution, and view the log entry from the console.log outputs.

This appears to be an intermittent problem. The two times it happened so far are:

  • We spotted the problem March 23 at about 09:00 CDT, but by around 14:00 CDT it started working correctly.
  • Today (March 26) the problem started happening again, from a different Atlas Trigger, roughly around 10:00 CDT, but stopped happening at about 11:30 CDT.

I’ve been able to make a stopgap fix which takes care of the most visible+ugly character encoding problem, using this (not in the Realm function, it’s in an AWS post-process function):

const { get, set } = require('lodash')
const stringifyKeys = require('stringify-keys')

function fixMongoDbMangling(document) {
        .forEach(key => {
            if (typeof get(document, key) === 'string') {
                set(document, key, get(document, key).replace(/â\u0080\u0099/g, '’'))

Update on 2021-03-26 13:01:45

It has been confirmed that this is an issue on our end and we are actively working on a fix.

I have passed this information along to our Realm Engineering Team to help in their efforts in resolving this issue.

Then a later update 2021-03-29 00:47:21

My colleagues on the Realm Engineering Team believe that they fixed the issue

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