CODEWITHSUNDEEP
mongodbtimestamp
xzyfer
xzyfer

Reputation: 14125

Mongo add timestamp field from existing date field

I currently have a collection with documents like the following:

{ foo: 'bar', timeCreated: ISODate("2012-06-28T06:51:48.374Z") }

I would now like to add a timestampCreated key to the documents in this collection, to make querying by time easier.

I was able to add the new column with an update and $set operation, and set the timestamp value but I appears to be setting the current timestamp using this:

db.reports.update({}, { 
    $set : { 
        timestampCreated : new Timestamp(new Date('$.timeCreated'), 0) 
    } 
}, false, true);

I however have not been able to figure out a way to add this column and set it's value to the timestamp of the existing 'timeCreated' field.

Upvotes: 5

Views: 3783

Answers (2)

chridam
chridam

Reputation: 103305

Use updateMany() which can accept aggregate pipelines (starting from MongoDB 4.2) and thus take advantage of the $toLong operator which converts a Date into the number of milliseconds since the epoch.

Also use the $type query in the update filter to limit only documents with the timeCreated field and of Date type:

db.reports.updateMany(
    { 'timeCreated': {
        '$exists': true,
        '$type': 9
    } },
    [
        { '$set': { 
            'timestampCreated': { '$toLong': '$timeCreated' } 
        } }
    ]
)

Upvotes: -1

jdi
jdi

Reputation: 92559

Do a find for all the documents, limiting to just the id and timeCreated fields. Then loop over that and generate the timestampCreated value, and do an update on each.

Upvotes: 3

Related Questions