This is a story about investigating how to use only createdAt with Mongoose’s timestamp options, but finding that I had to implement it in pre hooks myself.

options.timestamps Enables Both createdAt and updatedAt

First, at the time of Mongoose version 4.8.5, from reading the source code, options.timestamps doesn’t have an option to use only either createdAt or updatedAt.

• option: timestamps - Mongoose Schemas v4.8.5

Below is a partial excerpt from Mongoose’s source code:

/**
 * Setup updatedAt and createdAt timestamps to documents if enabled
 *
 * @param {Boolean|Object} timestamps timestamps options
 * @api private
 */
Schema.prototype.setupTimestamp = function(timestamps) {
  if (timestamps) {
    var createdAt = timestamps.createdAt || 'createdAt';
    var updatedAt = timestamps.updatedAt || 'updatedAt';
// ...
  }
};

• Source: lib/schema.js#L800-L809 at 4.8.5 · Automattic/mongoose

Sample Code to Enable Only createdAt

So here’s sample code that adds options.timestamps-like hooks to .pre(“save”), .pre(“findOneAndUpdate”), .pre(“update”), etc.

var yourSchema = new Schema({
  createdAt: {
    type: Date
  }
});

yourSchema.pre("save", function(next) {
  var now = new Date;
  if (this.isNew) {
    this.createdAt = now;
  }
  return next();
});

yourSchema.pre("findOneAndUpdate", function(next) {
  var now = new Date;
  this.findOneAndUpdate({}, {
    $setOnInsert: {
      createdAt: now
    }
  });
  return next();
});

yourSchema.pre("update", function(next) {
  var now = new Date;
  this.update({}, {
    $setOnInsert: {
      createdAt: now
    }
  });
  return next();
});

Finally, as a side note, there’s an issue about removing timestamp options, so checking that, it might be removed in version 4.11 milestone.

• Remove timestamp from mongoose options · Issue #3649 · Automattic/mongoose

That’s all from the Gemba.