Timestamps

Mongoose schemas support a timestamps option. If you set timestamps: true, Mongoose will add two properties of type Date to your schema:

  1. createdAt: a date representing when this document was created
  2. updatedAt: a date representing when this document was last updated

Mongoose will then set createdAt when the document is first inserted, and update updatedAt whenever you update the document using save(), updateOne(), updateMany(), findOneAndUpdate(), update(), replaceOne(), or bulkWrite().

const userSchema = new Schema({ name: String }, { timestamps: true });
const User = mongoose.model('User', userSchema);

let doc = await User.create({ name: 'test' });

console.log(doc.createdAt); // 2022-02-26T16:37:48.244Z
console.log(doc.updatedAt); // 2022-02-26T16:37:48.244Z

doc.name = 'test2';
await doc.save();
console.log(doc.createdAt); // 2022-02-26T16:37:48.244Z
console.log(doc.updatedAt); // 2022-02-26T16:37:48.307Z

doc = await User.findOneAndUpdate({ _id: doc._id }, { name: 'test3' }, { new: true });
console.log(doc.createdAt); // 2022-02-26T16:37:48.244Z
console.log(doc.updatedAt); // 2022-02-26T16:37:48.366Z

The createdAt property is immutable, and Mongoose overwrites any user-specified updates to updatedAt by default.

let doc = await User.create({ name: 'test' });

console.log(doc.createdAt); // 2022-02-26T17:08:13.930Z
console.log(doc.updatedAt); // 2022-02-26T17:08:13.930Z

doc.name = 'test2';
doc.createdAt = new Date(0);
doc.updatedAt = new Date(0);
await doc.save();

// Mongoose blocked changing `createdAt` and set its own `updatedAt`, ignoring
// the attempt to manually set them.
console.log(doc.createdAt); // 2022-02-26T17:08:13.930Z
console.log(doc.updatedAt); // 2022-02-26T17:08:13.991Z

// Mongoose also blocks changing `createdAt` and sets its own `updatedAt`
// on `findOneAndUpdate()`, `updateMany()`, and other query operations
doc = await User.findOneAndUpdate(
  { _id: doc._id },
  { name: 'test3', createdAt: new Date(0), updatedAt: new Date(0) },
  { new: true }
);
console.log(doc.createdAt); // 2022-02-26T17:08:13.930Z
console.log(doc.updatedAt); // 2022-02-26T17:08:14.008Z

Alternate Property Names

For the purposes of these docs, we'll always refer to createdAt and updatedAt. But you can overwrite these property names as shown below.

const userSchema = new Schema({ name: String }, {
  timestamps: {
    createdAt: 'created_at', // Use `created_at` to store the created date
    updatedAt: 'updated_at' // and `updated_at` to store the last updated date
  }
});

Disabling Timestamps

save(), updateOne(), updateMany(), findOneAndUpdate(), update(), replaceOne(), and bulkWrite() all support a timestamps option. Set timestamps: false to skip setting timestamps for that particular operation.

let doc = await User.create({ name: 'test' });

console.log(doc.createdAt); // 2022-02-26T23:28:54.264Z
console.log(doc.updatedAt); // 2022-02-26T23:28:54.264Z

doc.name = 'test2';

// Setting `timestamps: false` tells Mongoose to skip updating `updatedAt` on this `save()`
await doc.save({ timestamps: false });
console.log(doc.updatedAt); // 2022-02-26T23:28:54.264Z

// Similarly, setting `timestamps: false` on a query tells Mongoose to skip updating
// `updatedAt`.
doc = await User.findOneAndUpdate({ _id: doc._id }, { name: 'test3' }, {
  new: true,
  timestamps: false
});
console.log(doc.updatedAt); // 2022-02-26T23:28:54.264Z

// Below is how you can disable timestamps on a `bulkWrite()`
await User.bulkWrite([{
  updateOne: {
    filter: { _id: doc._id },
    update: { name: 'test4' },
    timestamps: false
  }
}]);
doc = await User.findOne({ _id: doc._id });
console.log(doc.updatedAt); // 2022-02-26T23:28:54.264Z

You can also set the timestamps option to an object to configure createdAt and updatedAt separately. For example, in the below code, Mongoose sets createdAt on save() but skips updatedAt.

let doc = new User({ name: 'test' });

// Tell Mongoose to set `createdAt`, but skip `updatedAt`.
await doc.save({ timestamps: { createdAt: true, updatedAt: false } });
console.log(doc.createdAt); // 2022-02-26T23:32:12.478Z
console.log(doc.updatedAt); // undefined

Disabling timestamps also lets you set timestamps yourself. For example, suppose you need to correct a document's createdAt or updatedAt property. You can do that by setting timestamps: false and setting createdAt yourself as shown below.

let doc = await User.create({ name: 'test' });

// To update `updatedAt`, do a `findOneAndUpdate()` with `timestamps: false` and
// `updatedAt` set to the value you want
doc = await User.findOneAndUpdate({ _id: doc._id }, { updatedAt: new Date(0) }, {
  new: true,
  timestamps: false
});
console.log(doc.updatedAt); // 1970-01-01T00:00:00.000Z

// To update `createdAt`, you also need to set `strict: false` because `createdAt`
// is immutable
doc = await User.findOneAndUpdate({ _id: doc._id }, { createdAt: new Date(0) }, {
  new: true,
  timestamps: false,
  strict: false
});
console.log(doc.createdAt); // 1970-01-01T00:00:00.000Z

Timestamps on Subdocuments

Mongoose also supports setting timestamps on subdocuments. Keep in mind that createdAt and updatedAt for subdocuments represent when the subdocument was created or updated, not the top level document. Overwriting a subdocument will also overwrite createdAt.

const roleSchema = new Schema({ value: String }, { timestamps: true });
const userSchema = new Schema({ name: String, roles: [roleSchema] });

let doc = await User.create({ name: 'test', roles: [{ value: 'admin' }] });
console.log(doc.roles[0].createdAt); // 2022-02-27T00:22:53.836Z
console.log(doc.roles[0].updatedAt); // 2022-02-27T00:22:53.836Z

// Overwriting the subdocument also overwrites `createdAt` and `updatedAt`
doc.roles[0] = { value: 'root' };
await doc.save();
console.log(doc.roles[0].createdAt); // 2022-02-27T00:22:53.902Z
console.log(doc.roles[0].updatedAt); // 2022-02-27T00:22:53.902Z

// But updating the subdocument preserves `createdAt` and updates `updatedAt`
doc.roles[0].value = 'admin';
await doc.save();
console.log(doc.roles[0].createdAt); // 2022-02-27T00:22:53.902Z
console.log(doc.roles[0].updatedAt); // 2022-02-27T00:22:53.909Z

Under the Hood

For queries with timestamps, Mongoose adds 2 properties to each update query:

  1. Add updatedAt to $set
  2. Add createdAt to $setOnInsert

For example, if you run the below code:

mongoose.set('debug', true);

const userSchema = new Schema({
  name: String,
}, { timestamps: true });
const User = mongoose.model('User', userSchema);

await User.findOneAndUpdate({}, { name: 'test' });

You'll see the below output from Mongoose debug mode:

Mongoose: users.findOneAndUpdate({}, { '$setOnInsert': { createdAt: new Date("Sun, 27 Feb 2022 00:26:27 GMT") }, '$set': { updatedAt: new Date("Sun, 27 Feb 2022 00:26:27 GMT"), name: 'test' }}, {...})

Notice the $setOnInsert for createdAt and $set for updatedAt. MongoDB's $setOnInsert operator applies the update only if a new document is upserted. So, for example, if you want to only set updatedAt if the document if a new document is created, you can disable the updatedAt timestamp and set it yourself as shown below:

await User.findOneAndUpdate({}, { $setOnInsert: { updatedAt: new Date() } }, {
  timestamps: { createdAt: true, updatedAt: false }
});