Document.prototype.getChanges()

Returns:

• «Object»

Returns the changes that happened to the document in the format that will be sent to MongoDB.

Example:

const userSchema = new Schema({
  name: String,
  age: Number,
  country: String
});
const User = mongoose.model('User', userSchema);
const user = await User.create({
  name: 'Hafez',
  age: 25,
  country: 'Egypt'
});
// returns an empty object, no changes happened yet
user.getChanges(); // { }
user.country = undefined;
user.age = 26;
user.getChanges(); // { $set: { age: 26 }, { $unset: { country: 1 } } }
await user.save();
user.getChanges(); // { }

Modifying the object that getChanges() returns does not affect the document’s change tracking state. Even if you delete user.getChanges().$set, Mongoose will still send a $set to the server.