Mongoose/Mongo find in array of objectIds

With Mongoose you have to force cast your string as an ID in some cases. Usually it automatically does this for you, but in your specific case, it doesn't. The following snippet of code will get all connections that contain the passed ID.

var mongoose = require('mongoose');
Node.find({ connections: mongoose.Types.ObjectId("535c5c1b8aa6dc5f021e8a98") }, function (err, results) { 
    console.log(results); 
});