Sample validation

schema.js

var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/my_database');

var Schema = mongoose.Schema
  , ObjectId = Schema.ObjectId;


var BlogPost = new Schema({
    author             : ObjectId
  , title              : String
  , body               : String
  , date               : Date
  , comments           : [Comment]
  , min_commenter_age  : Number
});

var Comment = new Schema({
    name  :  { type: String, default: 'hahaha' }
  , age   :  { type: Number, min: 18, index: true }
  , bio   :  { type: String, match: /[a-z]/ }
  , date  :  { type: Date, default: Date.now }
});

Comment.path( 'age' ).validate( function(v){
//How to get the minimum age from the blog post that contains this schema
}, "minimum age");