Peculiar behavior when using

i have a document with one of the fields is an array of objects.

i updated one of the objects and called .save() on the document.

the promise is resolved and the returned document shows the updates (code below) => {   

console.log(savedDoc) // THE UPDATES ARE SHOWING HERE!! All good till here!

savedDoc === doc; // true });

now here is the strange part - the updates are not written down into the database!

what am I missing??

Hello @Sangram_Chahal, welcome to the MongoDB Community forum.

You need to pass the document to be inserted to the method. For example:

    .save(doc).then(writeResult => {
        console.log(writeResult.result, writeResult.ops);

The output, in addition to inserting the document into the collection, prints:

{ n: 1, ok: 1 } [ <the inserted document> ]

Also, note the documentation says:

save is - Deprecated: use insertOne, insertMany, updateOne or updateMany

In your case, use insertOne.

Also see these topics from the NodeJS Driver documentation: