tmp.js

var mongoose = require('mongoose')
var Schema = mongoose.Schema

console.error('mongoose version %s', mongoose.version);

var s = new Schema({ name: String })
s.pre('init', function (next, doc) {
  console.error('pre', arguments);
  var changed = { name: doc.first + ' ' + doc.last };
  next(changed);
});

var P = mongoose.model('Person', s);

var p = new P;
p.init({ first: 'aaron', last: 'heckmann'});

console.error('p is %j', p);