object.js

var fwk = require('fwk');

/**
 * Object generic
 *
 * Implements simple methods to modifiy
 * objects in database
 * @inherits events.EventEmitter
 *
 * @param {mongo, cfg, collection, uid, [obj]}
 */
var object = function(spec, my) {
  my = my || {};
  var _super = {};        

  my.cfg = spec.cfg;  
  my.mongo = spec.mongo;

  my.collection = spec.collection;
  my.uid = spec.uid;

  if(spec.obj)
    my.cache = spec.obj;
 
  // public
  var get;
  var exist;
  var remove;
  var save;
 
  var db_find;
  var db_post;

  // private
  var invalidate;

  var that = {};  
  
  /**
   * Retrieve object from database or cache if 
   * already in
   * @param cb callback function(err, objs)
   */
  get = function(cb) {
    var get_object = function(key, cb) {
      var c = my.mongo.collection(my.collection);
      c.find({uid: key}, function(err, cursor) {
        if(err) cb(err);
        else {
          cursor.toArray(function(err, items) {
            if(err) cb(err);
            else {
              if(items && items.length > 0) {
                cb(null, items[0]);
              }
              else {
                cb(null, null);
              }
            }
          });
        }
      });
    };
    
    if(my.cache) {
      cb(null, my.cache);
    }
    else {
      get_object(my.uid, function(err, obj) {
        if(err) cb(err);
        else {
          my.cache = obj;
          cb(null, obj);
        }
      });
    }
  };

  /**
   * Check if an object exists for uid
   * @param cb callback function(err, bool)
   */
  exist = function(cb) {
    get(function(err, item) {
      if(err) cb(err);
      else if(item) {
        cb(null, true);
      }
      else {
        cb(null, false);
      }
    });
  };

  
  /**
   * Remove object from database
   * @param query the request query
   * @param cb callback function(err)
   */
  remove = function(cb) {
    var c = my.mongo.collection(my.collection);
    c.remove({uid: my.uid}, {safe:true}, function(err) {
      if(err) cb(err);
      else {
        delete my.cache;
        cb();          
      }
    });
  };
  
  /**
   * Update object in database
   * @param obj the obj to update
   * @param cb callback function(err)
   */ 
  save = function(obj, cb) {
    obj.uid = my.uid;
    my.cache = obj;
 
    var c = my.mongo.collection(my.collection);
    c.update({uid: my.uid}, obj, 
             {upsert: true, multi: false, safe: true}, function(err) {
               if(err) cb(err);
               else {
                 cb();
               }
             });        
  };  

  /**
   * db helper to find elements
   * @param collection the collection to use
   * @param query a query
   */
  db_find = function(collection, query, cb) {
    var c = my.mongo.collection(collection);
    c.find(query, function(err, cursor) {
      if(err) cb(err);
      else {
        cursor.toArray(cb);
      }
    });
  };

  /**
   * db helper function to post element
   * @param collection
   */
  db_post = function(collection, obj, cb){
    var c = my.mongo.collection(collection);
    c.insert(obj, cb);
  };
  
  fwk.method(that, 'get', get, _super);
  fwk.method(that, 'exist', exist, _super);
  fwk.method(that, 'remove', remove, _super);
  fwk.method(that, 'save', save, _super);

  fwk.method(that, 'db_find', db_find, _super);
  fwk.method(that, 'db_post', db_post, _super);
  
  return that;
};

exports.object = object;