Problem getting session in nodejs from mongodb?

Question

MongoDB

A session is created using the express-session module . I use mongodb as storage.
The following entry appears in the database

. session was created with id PmIBbN8NWAaxBUEW8J6ban4P . Everything is good here. Then a websocket connection is established using the ws module between the client and the server, but before establishing the connection, you need to check that the user has a session and that he is registered. Here comes the problem. Can't get session content by id.
To work with mongodb I use mongoose
I created the following model:

var Schema = mongoose.Schema;

var schema = new Schema({
    session:{
        type: String
    },
    expires:{
        type: Date
    }
});

exports.Session = mongoose.model('Session', schema);

But when executing such a query, it does not find anything

Session.findById("PmIBbN8NWAaxBUEW8J6ban4P", function(err, session){
      ...
})

What is the problem?

Answer 1

The problem was solved by changing the Session model

var Schema = mongoose.Schema;

var schema = new Schema({
    _id:{
        type: String
    },
    session:{
        type: String
    },
    expires:{
        type: Date
    }
});

exports.Session = mongoose.model('Session', schema);

The _id field must also be described.