mongodb: How to create _id for each array element?

Question

Is there a way that whenever I $push a new element in monodb array, a normal _id is added to it? I remember that mongoose was doing something like that automatically but now I am using mongodb's native js and it seems to be not inserting any _id.

Example:

chats.updateOne({_id: chat_id},
            {$push: {messages: 
                    {
                        message: data.message,
                        date: new Date(),
                    }}},
            function(err, response){}
)};

On executing, messages array should have regular _id field, message and date. Currently it only creates message and date.

You need to create schema for messages

Vicky Gonsalves
– Vicky Gonsalves

2016-01-28 14:49:05 +00:00
Commented Jan 28, 2016 at 14:49 — Vicky Gonsalves
– Vicky Gonsalves, Commented Jan 28, 2016 at 14:49

Alex Blex · Accepted Answer · 2016-01-28 15:08:00Z

3

You can use ObjectId():

chats.updateOne({_id: chat_id},
            {$push: {messages: 
                    {
                        message: data.message,
                        date: new Date(),
                        _id: ObjectId()
                    }}},
            function(err, response){}
)};

answered Jan 28, 2016 at 15:08

Alex Blex

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1 Comment

Cashif Ilyas Over a year ago

ObjectId() is not the same function in NodeJS driver as in mongo Shell. Alternative is ObjectID.createFromTime(time). Just to help the future visitors. Docs: mongodb.github.io/node-mongodb-native/api-bson-generated/…

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