MongoDB shell: How to remove specific elements in all the collections inside a DB

Question

I would like to remove, in all collections, all coincidences with a regex expression.

I need this, because a JSON parser failed in my app at a certain point today, and now the database is corrupted.

I could do it by hand, but I have over 100+ collections, and manually entering in mongo shell db["X"].remove({ "DateTime": { $regex : "2015-11-16" } }) for each collection would take quite a few time.

Do you know any way to perform this automatically inside mongo shell? I always access this database via package RMongo in R, and I could do it via dbRemoveQuery(rmongo.object, collection, query) but I was wondering if it could be done inside mongo shell, maybe a little quicker.

Answer 1

use yourDbName

// Get the names of all collections in the database.
var names = db.getCollectionNames();

// Iterate over every collection name.
for(i = 0; i < names.length; i++) {

    // Only issue the query if the collection is not a system collection.
    if(!names[i].startsWith("system.")) {

        // Issue the query against the collection with the name `names[i]`.
        db[names[i]].remove({ "DateTime": { $regex : "2015-11-16" } });
    }
}

Please note that I am excluding system collections from the list.