Question

Is there a way to delete objects from multiple collections? Like delete everything in this 5 collections command in MongoDB?

It is kind of time consuming to go and manually delete from each collection in a Mongo database.

Answer 1

As Andrew mentioned, there is no built in way to do this, but you can use Javascript to get what you want. For example, if I wanted to drop a list of databases quickly (and dirtily, this is just a proof-of-concept code sample!):

var deletelist = ["deleteme1", "deleteme2", "deleteme3"]
deletelist.forEach(
    function deletedbs(name) {
        db = db.getMongo().getDB( name );
        db.dropDatabase();
        print(name + " deleted");
    }
)

No error checking of course, but this kind of server side script will work for cross-collection and cross-database functionality. If you wanted to run something on all your databases, then you could construct the list like this:

var allDBs = db.getMongo().getDBNames()
for(var name in allDBs){
      db = db.getMongo().getDB( name );
      db.<command to execute on each DB>;
 }

Of course, you need to be very, very careful when running things like this so you avoid destroying your database, so test extensively and use judiciously 🙂

For more on server side JS, check out the MongoDB docs here:

http://www.mongodb.org/display/DOCS/Server-side+Code+Execution