MongoDB / Express - How to switch database after connecting via connect()

Question

I am using express to connect to my mongoDB:

mongodb.MongoClient.connect(mongourl, function(err, database) {

      // How would one switch to another database here?

});

I have to connect to the admin database in the first place. After the conenction has been established, i would like to switch the database.

Although i have searched through the official documentation, i was unable to find something that fits my needs.

I am aware of the MongoClient::open() method, but i would like to stick to connect().

Any help is appreciated.

Answer 1

You can switch to another database like so:

mongodb.MongoClient.connect(mongourl, function(err, database) {
  // switch to another database
  database = database.db(DATABASE_NAME);
  ...
});

(docs)

EDIT: for clarification: this also allows you to open multiple databases over the same connection:

mongodb.MongoClient.connect(mongourl, function(err, database) {
  // open another database over the same connection
  var database2 = database.db(DATABASE_NAME);

  // now you can use both `database` and `database2`
  ...
});

Answer 2

You just have to call MongoClient.connect once again, because there is one connection per database. That means, you cannot change the database of an existing connection. You have to connect a second time:

mongodb.MongoClient.connect(mongourl, function(err, database) {
    mongodb.MongoClient.connect(mongourl_to_other_database, function(err, database2) {
        // use database or database2
    });
});