mongooseでSchema定義してないpropertyに値をセットする ref: http://qiita.com/bells17/items/cafe8f0b3e285e9e8ab4

file0.txt

var somethingSchema = new Schema({
  field: String
});
var Something = mongoose.model('Something', somethingSchema);

var something = new Something();

something.not_defined_field = 'Not defined field value';
something('not_defined_field'); // -> undefined
something.not_defined_field; // -> undefined


something.set('not_defined_field', 'Not defined field value', { strict: false });
something('not_defined_field'); // -> 'Not defined field value'
something.not_defined_field; // -> undefined