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Jigar
Jigar

Reputation: 1374

How to add createAt field into Mongodb using _id as timestamp

I have a user collection with already existed of 200 data and i forgot to set createAt field in schema

now i want to update all the existed field and add into database using (_id) which is already a timestamp

so all i want is a query which take the _id and convert into date and save into existed data (i am using robo 3T )

please sorry if i have asked silly question. I am new to mongodb

Upvotes: 0

Views: 1263

Answers (2)

prasad_
prasad_

Reputation: 14317

You can use any of these two queries to create the createdAt field with the date/timestamp from _id. The first one works MongoDb version 4.0+ and the second with MongoDB version 4.2.

Note these work in Mongo Shell, and not tested in robo3T.

db.test.aggregate( [
  { 
      $project: { createdAt: { $toDate: "$_id" } } 
  }
] ).forEach( doc => db.test.updateOne( { _id: doc._id }, { $set: { createdAt: doc.createdAt } } ) )


db.test.updateMany(
  { },
  [
      { $set: { createdAt: { $toDate: "$_id" } } }
  ]
)

Upvotes: 1

Alok Deshwal
Alok Deshwal

Reputation: 1126

This is robo mongo query, it won't work in mongo console. 

db.getCollection('collectionNameGoesHere').find({}, {
    _id: 1
}).forEach(function (doc) {
    db.getCollection('collectionNameGoesHere').update({
        _id: doc._id
    }, {
        $set: {
            createdAt: doc._id.getTimestamp()
        }
    }, {
        upsert: false,
        multi: true
    })
});

Upvotes: 1

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