CODEWITHSUNDEEP
mongodbmongodb-query
Ebram Shehata
Ebram Shehata

Reputation: 621

Native way to add createdAt in MongoDB

Question in short: Is there anyway to automatically add createdAt field to each document inserted in a collection in MongoDB?

Scenario: I'm using a dockerized instance of MongoDB and I want to automatically add createdAt field to every document on insertion. I want to achieve this using MongoDB itself because the database can have multiple input channels like Logstash, Python code, ..etc.

Note: I should be able to execute JavaScript code using init file in docker-entrypoint-initdb.d.

Is there a hook or something I can use to automatically achieve this ?

Upvotes: 6

Views: 7180

Answers (1)

R2D2
R2D2

Reputation: 10697

Natively the createdAt timestamp is contained inside the first 4 bytes in the default mongoDB _id field in newly inserted document , so generally you dont need one more field that will contain same data:

> db.yourCollection.findOne()._id.getTimestamp()
ISODate("2022-05-05T02:57:31Z")

But modern frameworks add this option so for example in node.js you can add something like this:

 var yourSchema = new Schema({..});
 yourSchema.set('timestamps', true);

which will add the "createdAt" and "updatedAt" fields to the document automatically on insert or update operations via the framework... or if you need only createdAt:

 var yourSchema = new Schema({..}, { timestamps: { createdAt: 'created_at' } });

There is also an option called $setOnInsert where you can add the createdAt during upsert operation:

 db.yourCollection.updateOne(
  { _id: 1 },
  {
   $set: { item: "Some item" },
    $setOnInsert: { createdAt: new Date() }
  },
  { upsert: true }
 )

Upvotes: 7

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