CODEWITHSUNDEEP
arraysnode.jsmongodbexpressmongoose
jack blank
jack blank

Reputation: 5203

Delete documents from collection and remove Ids from an array in another collection

I have a reviews collection and a users collection. In the users collection I have docs that have an array called reviews that contains the _ids of the review from the reviews collection. Sometimes I go to the mongo terminal and delete reviews from the reviews collection that I don't want from the reviews collection. for example I would delete all that don't have a specific field. the problem is I would also like to delete the review id in the reviews array. I do a simple db.collection.remove on the reviews collection so that is easy.(that would delete like 50 reviews). I was wondering how to remove ids in the reviews array easily. Any ideas? I use mongoose but I was wondering if there was an easy way to do in the terminal. I think the only association is the ids.

I no how to use $pull but I want to make it pull the ids every time a specific review is removed.

Upvotes: 1

Views: 1407

Answers (1)

chridam
chridam

Reputation: 103305

You certainly can't do this with a single atomic update as you have two collections to update. What you can do is carry out two operations in series i.e. the removal of the specific reviews from the reviews collection and then use the $pullAll operator to delete the values from reviews array in the users collection.

The following mongo shell example shows this:

var reviewIds = [
    ObjectId("582ebf010936ac3ba5cd00e2"),
    ObjectId("582ebf010936ac3ba5cd00e3"),
    ...
];

db.reviews.remove({ "_id": { "$in": reviewIds } });
db.users.updateMany(
    { "reviews": { "$in": reviewIds } },
    { "$pullAll": { "reviews": reviewIds } }
);

For a single review id, you can just use the $pull operator as

db.reviews.remove({ "_id": reviewId });
db.users.updateMany(
    { "reviews": reviewIds },
    { "$pull": { "reviews": reviewId } }
);

Upvotes: 2

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