Mongoose $lookup where localField is a string of an ObjectId in foreignField

Question

I want to do a $lookup where the localField is a String representation of an ObjectId and the foreign field is an actual ObjectId.

Any idea if this is possible with MongoDB 3.2 if items is a String value but _id is an ObjectId?

[{
    "$lookup": {
        "from": "videos",
        "localField": "items",
        "foreignField": "_id",
        "as": "appendedItems"
    }
}]

to use `$lookup` data type should be same for `localField` and `foreignField` — Shaishab Roy, Feb 13 '17 at 10:10
@ShaishabRoy, so is it possible if both are ObjectID types (and not strings)? — Yuval A., May 26 '18 at 14:01

score 2 · Accepted Answer · answered Feb 14 '17 at 09:25

It is not possible to match string with ObjectId in $lookup in mongodb version 3.2, there are some tickets opened for this issue, you can follow these issue and also vote for them.

https://jira.mongodb.org/browse/SERVER-22781

https://jira.mongodb.org/browse/SERVER-24947

Mongoose $lookup where localField is a string of an ObjectId in foreignField

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