added caching functionnality

lib/abstract-class.js

@@ -37,6 +37,13 @@ AbstractClass.prototype._initProperties = function (data, applySetters) {
     var properties = ds.properties;
     data = data || {};
 
+    Object.defineProperty(this, '__cachedRelations', {
+        writable: true,
+        enumerable: false,
+        configurable: true,
+        value: {}
+    });
+
     Object.defineProperty(this, '__data', {
         writable: true,
         enumerable: false,
@@ -723,15 +730,32 @@ AbstractClass.belongsTo = function (anotherClass, params) {
     };
 
     this.prototype[methodName] = function (p) {
+        var self = this;
+        var cachedValue = null;
+        if (this.__cachedRelations && this.__cachedRelations[methodName]) {
+            cachedValue = this.__cachedRelations[methodName];
+        }
         if (p instanceof AbstractClass) { // acts as setter
             this[fk] = p.id;
+            this.__cachedRelations[methodName] = p;
         } else if (typeof p === 'function') { // acts as async getter
-            this.__finders__[methodName](this[fk], p);
-            return this[fk];
+            if (cachedValue === null) {
+                this.__finders__[methodName](this[fk], function(err, inst) {
+                    if (!err) {
+                        self.__cachedRelations[methodName] = inst;
+                    }
+                    p(err, inst);
+                });
+                return this[fk];
+            } else {
+                p(null, cachedValue);
+                return cachedValue;
+            }
         } else if (typeof p === 'undefined') { // acts as sync getter
-            return this[fk];
+            return cachedValue || this[fk];
         } else { // setter
             this[fk] = p;
+            this.__cachedRelations[methodName] = p;
         }
     };
 
@@ -766,18 +790,34 @@ function defineScope(cls, targetClass, name, params, methods) {
         enumerable: false,
         configurable: true,
         get: function () {
-            var f = function caller(cond, cb) {
-                var actualCond;
+            var f = function caller(condOrRefresh, cb) {
+                var actualCond = {};
+                var actualRefresh = false;
                 if (arguments.length === 1) {
-                    actualCond = {};
-                    cb = cond;
+                    cb = condOrRefresh;
                 } else if (arguments.length === 2) {
-                    actualCond = cond;
-                } else {
-                    throw new Error('Method only can be called with one or two arguments');
+                    if (typeof condOrRefresh === 'boolean') {
+                        actualRefresh = condOrRefresh;
+                    } else {
+                        actualCond = condOrRefresh;
+                    }
+                } else if (arguments.length > 2) {
+                    throw new Error('Method only can\'t be called with more than two arguments');
                 }
 
-                return targetClass.all(mergeParams(actualCond, caller._scope), cb);
+                if (!this.__cachedRelations || !this.__cachedRelations[name] || actualRefresh) {
+                    var self = this;
+                    return targetClass.all(mergeParams(actualCond, caller._scope), function(err, data) {
+                        self.__cachedRelations[name] = data;
+                        cb(err, data);
+                    });
+                } else {
+                    if (cb) {
+                        cb(null, this.__cachedRelations);
+                    } else {
+                        return this.__cachedRelations[name];
+                    }
+                }
             };
             f._scope = typeof params === 'function' ? params.call(this) : params;
             f.build = build;