Check if MongoDB upsert did an insert or an update

Question

Yes there is, on a safe call (or getLastError) the update function will return an array with an upsert field and a updatedExisting field.

You can read the PHP version of this here: http://php.net/manual/en/mongocollection.insert.php towards the bottom.

As it says within the documentation on upserted:

If an upsert occured, this field will contain the new record's _id field. For upserts, either this field or updatedExisting will be present (unless an error occurred).

So upserted contains the _id of the new record if a insert was done or it will increment updatedExisting if it updated a record.

I am sure a similar thing appears in all drivers.

Edit

It will actually be a boolean in the updatedExisting field of true or false

For reference only, in node.js:

collection.update( source, target, { upsert: true }, function(err, result, upserted) {
  ...
});

For reference only, in node.js using Mongoose 3.6:

model.update( findquery, updatequery, { upsert: true }, function(err, numberAffected, rawResponse) {
  ...
});

Where rawResponse looks like this when it has updated an existing document:

{ updatedExisting: true,
  n: 1,
  connectionId: 222,
  err: null,
  ok: 1 }

And it looks like this when it has created a new document:

{ updatedExisting: false,
  upserted: 51eebc080eb3e2208a630d8e,
  n: 1,
  connectionId: 222,
  err: null,

(Both cases would return numberAffected = 1)

The Answer was taken from "MongoDB Applied Design Patterns" Book !determine whether an upsert was an insert or an update

Using MongoDB driver 3.5.9 under Node.js, I found that there are these properties we are interested in after using updateOne with { upsert: true }:

{
  modifiedCount: 0,
  upsertedId: null,
  upsertedCount: 0,
  matchedCount: 1
}

When upsert inserted something, we will get upsertedCount > 0 and upsertedId will hold the newly inserted document ID. When upsert modified something, we will get modifiedCount > 0.

The tutorial for all CRUD operations is here https://mongodb.github.io/node-mongodb-native/3.6/tutorials/crud/