MongoDB $pull syntax

Question

I\'m having a (hopefully) small syntax problem with $pull in Mongodb.

bulk.find({_id: new mongo.ObjectID(req.session._id)}).updateOne({$pull: {
  firstArray: {i         


        

Answer 1

Your "secondArray" has a nested element structure, so you must identify the outer element you want to match in your query when using a positional $ operator in the update. You basically need something like this:

bulk.find({ 
    "_id": new mongo.ObjectID(req.session._id), 
    "secondArray._id": "7423" 
}).update({
    "$pull": { 
        "firstArray": { "_id": "153" },
        "secondArray.$.firstArrayIds": 153
    }
});

So there are in fact "two" id values you need to pass in with your request in addition to the general document id. Even though this is nested it is okay since you are only matching on the "outer" level and only on one array. If you tried to match the position on more than one array then this is not possible with the positional operator.