tokland

_.mixin({
  /* Like extend but get key/values object->key_names */ 
  extend_from: function(object, source_object, key_names) {   
    return _(object).extend(_(source_object).slice(key_names));
  },
  
  /* Return a new object with the merged properties of all objects in arguments */
  merge: function() {
    var objects = arguments;
    return _.reduce(_.rest(objects), function(obj, o) {

madhums

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

// map function
var map = function(){
  emit(this.field_to_group_by, {
    other_fields: this.other_fields
    // list other fields like above to select them
  })
}