[mongoose] Statics loading reference list of objects

Here is my code:

var DocSchema = new Schema({

    clauseList: [{

        type: Schema.ObjectId,

        ref: 'Clause'

    }],

    user: {

        type: Schema.ObjectId,

        ref: 'User'

    }

});

DocSchema.statics.load = function(id, cb) {

    this.findOne({

        _id: id

    }).populate('user', 'name username').exec(cb);

};

I want to automatically load clauses list like loading the user. Help me please!