convert a field inside an array of objects. mongodb aggregation

Question

I have a document like this:

{
    "_id" : ObjectId("5e22a400d4abfae27d173292"),
    "bundle_items" : [ 
        {
            "id" : "5e201c30d4abfae27d171851"
        }, 
        {
            "id" : "5e201c3dd4abfae27d171862"
        }, 
        {
            "id" : "5e201c4e66cb0c3ede4124d5"
        }
    ]
}

And my aggregation is:

[
        {
            $lookup : {
                from : 'product',
                localField   : 'bundle_items.id', // problem is here, i need this field to be ObjectId
                foreignField : '_id',
                as: 'bundle_items_objects'    
            }
        },{
            $project: {
                'bundle_total_regular_prices': {
                '$sum': '$bundle_items_objects.regular_price'
                },
                'bundle_items' : 1,
            }
        }
]

How can i convert bundle_items.*.id to ObjectId in my aggregation?

i can't change it on database because of some reasons.

You can use the aggregation operator $toObjectId to convert from a string "5e201c4e66cb0c3ede4124d5" to ObjectId. — prasad_
– prasad_, Commented Jan 18, 2020 at 6:50
@prasad_ thanks, i tried it but failed. the problem is bundle_items is an array, and i don't want to unWind it, bacause of performance matter. — Amin Shojaei
– Amin Shojaei, Commented Jan 18, 2020 at 6:52

Amin Shojaei · Accepted Answer · 2020-01-18 07:29:37Z

4

You can add below stage before $lookup stage

{
        "$addFields": {
        "bundle_items": {
          "$map": {
                "input": "$bundle_items",
                "in": {
                    id: {
                        "$toObjectId": "$$this.id"
                    }
                }
            }
        }
      }
  }

edited Jan 18, 2020 at 7:29

Amin Shojaei

6,7882 gold badges44 silver badges51 bronze badges

answered Jan 18, 2020 at 6:53

Ashh

46.6k16 gold badges111 silver badges137 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

convert a field inside an array of objects. mongodb aggregation

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related