MongoDb.js / Mongoose find() translate a String in ObjectId

I have two schemas utilizing Mongoose

Schema 1 var schema = mongoose.Schema({

    name: {
        type: String,
        required: true
    }
});
return mongoose.model('User', schema);

Schema 2

var schema = mongoose.Schema({

    name: {
        type: String,
        required: true
    },
    user: {
        type: mongoose.Schema.ObjectId,
        ref: 'User',
        required: true
    }
});
return mongoose.model('Page', schema);

My Data in Page Collection

_id

551b0cdf63dc96e9c39de0f8

551b0d1563dc96e9c39de0f9

551b0d2d63dc96e9c39de0fa

551b0d4363dc96e9c39de0fb

551daae0f4cb312c62dcbc1e

name

Cazaquistao

Russia

China

Australia

El Salvador

user

5515c7aaaf6d59fea26d7185

5515c7aaaf6d59fea26d7185

5515c7aaaf6d59fea26d7185

5515c7aaaf6d59fea26d7185

5515c7c9af6d59fea26d7186

when i search in schema 2 by user, I dont find any results.

The mongoose translate the mongoose converts the query erroneously.

Query

var test = Page.find().select("_id").where({"user" : "5515c7aaaf6d59fea26d7185"}).exec()                  
 .then(function (t) {                
   console.log("hi", t);                
   });

Query Translated erroneously

db.pages.find({ user: ObjectId("5515c7aaaf6d59fea26d7185") })

no results

Query as it should be

db.pages.find({ user: "5515c7aaaf6d59fea26d7185" })

4 results

Any suggestions of what to do to work around this?