diff --git a/lib/abstract-class.js b/lib/abstract-class.js
index a8cb79a5..5d4a36a4 100644
--- a/lib/abstract-class.js
+++ b/lib/abstract-class.js
@@ -58,6 +58,10 @@ AbstractClass.prototype._initProperties = function (data, applySetters) {
         value: {}
     });
 
+    if (data['__cachedRelations']) {
+        this.__cachedRelations = data['__cachedRelations'];
+    }
+
     for (var i in data) this.__data[i] = this.__dataWas[i] = data[i];
 
     if (applySetters && ctor.setter) {
@@ -384,6 +388,202 @@ AbstractClass.count = function (where, cb) {
     this.schema.adapter.count(this.modelName, cb, where);
 };
 
+/**
+ *
+ *
+ * @param objects
+ * @param include
+ */
+AbstractClass.include = function (objects, include, callback, preprocessDataCallback) {
+    var self = this;
+
+    if ((include.constructor.name == 'Array' && include.length == 0) || (include.constructor.name == 'Object' && Object.keys(include).length == 0)) {
+        callback(null, objects);
+        return;
+    }
+
+    console.log('******************* OLD INCLUDE', include);
+    include = processIncludeJoin(include);
+    console.log('******************* NEW INCLUDE', include);
+
+    var keyVals = {};
+    var objsByKeys = {};
+
+    var nbCallbacks = 0;
+    for (var i = 0; i < include.length; i++) {
+        var cb = processIncludeItem(objects, include[i], keyVals, objsByKeys);
+        if (cb !== null) {
+            nbCallbacks++;
+            cb(function() {
+                nbCallbacks--;
+                if (nbCallbacks == 0) {
+                    callback(null, objects);
+                }
+            });
+        }
+    }
+
+
+
+      /*
+    async.parallel(callbacks, function(err, results) {
+        callback(null, objs);
+    });
+    */
+
+    function processIncludeJoin(ij) {
+        if (typeof ij === 'string') {
+            ij = [ij];
+        }
+        if (ij.constructor.name === 'Object') {
+            var newIj = [];
+            for (var key in ij) {
+                var obj = {};
+                obj[key] = ij[key];
+                newIj.push(obj);
+            }
+            return newIj;
+        }
+        return ij;
+    }
+
+    function processIncludeItem(objs, include, keyVals, objsByKeys) {
+        var relations = self.relations;
+
+        if (include.constructor.name === 'Object') {
+            var relationName = Object.keys(include)[0];
+            var subInclude = include[relationName];
+        } else {
+            var relationName = include;
+            var subInclude = [];
+        }
+        var relation = relations[relationName];
+
+        var req = {'where': {}};
+        var keysToBeProcessed = {};
+        if (!keyVals[relation.keyFrom]) {
+            objsByKeys[relation.keyFrom] = {};
+            for (var j = 0; j < objs.length; j++) {
+                keysToBeProcessed[objs[j][relation.keyFrom]] = true;
+                if (!objsByKeys[relation.keyFrom][objs[j][relation.keyFrom]]) {
+                    objsByKeys[relation.keyFrom][objs[j][relation.keyFrom]] = [];
+                }
+                objsByKeys[relation.keyFrom][objs[j][relation.keyFrom]].push(objs[j]);
+            }
+            keyVals[relation.keyFrom] = Object.keys(objsByKeys[relation.keyFrom]);
+        }
+
+        if (keyVals[relation.keyFrom].length > 0) {
+            // deep clone is necessary since inq seems to change the processed array
+            var inValues = [];
+            for (var j = 0; j < keyVals[relation.keyFrom].length; j++) {
+                if (keyVals[relation.keyFrom][j] !== 'null') {
+                    inValues.push(keyVals[relation.keyFrom][j]);
+                }
+            }
+
+            req['where'][relation.keyTo] = {inq: inValues};
+            req['include'] = subInclude;
+
+            return function(cb) {
+                relation.modelTo.all(req, function(err, dataIncluded) {
+                    var objsIncluded = preprocessDataCallback(relation.modelTo.modelName, dataIncluded);
+                    for (var i = 0; i < objsIncluded.length; i++) {
+                        delete keysToBeProcessed[objsIncluded[i][relation.keyTo]];
+                        var objectsFrom = objsByKeys[relation.keyFrom][objsIncluded[i][relation.keyTo]];
+                        for (var j = 0; j < objectsFrom.length; j++) {
+                            if (!objectsFrom[j].__cachedRelations) {
+                                objectsFrom[j].__cachedRelations = {};
+                            }
+                            if (relation.multiple) {
+                                if (!objectsFrom[j].__cachedRelations[relationName]) {
+                                    objectsFrom[j].__cachedRelations[relationName] = [];
+                                }
+                                objectsFrom[j].__cachedRelations[relationName].push(objsIncluded[i]);
+                            } else {
+                                objectsFrom[j].__cachedRelations[relationName] = objsIncluded[i];
+                            }
+                        }
+                    }
+
+                    // No relation have been found for these keys
+                    for (var key in keysToBeProcessed) {
+                        var objectsFrom = objsByKeys[relation.keyFrom][key];
+                        for (var j = 0; j < objectsFrom.length; j++) {
+                            if (!objectsFrom[j].__cachedRelations) {
+                                objectsFrom[j].__cachedRelations = {};
+                            }
+                            objectsFrom[j].__cachedRelations[relationName] = relation.multiple ? [] : null;
+                        }
+                    }
+                    cb(err, objsIncluded);
+                });
+            };
+        }
+
+
+        return null;
+    }
+
+
+
+    /*
+    function processIncludeItem(model, objs, include, keyVals, objsByKeys) {
+        var relations = model.relations;
+
+        if (include.constructor.name === 'Object') {
+            var relationName = Object.keys(include)[0];
+            var relation = relations[relationName];
+            var subInclude = include[relationName];
+        } else {
+            var relationName = include;
+            var relation = relations[relationName];
+            var subInclude = [];
+        }
+
+        var req = {'where': {}};
+        if (!keyVals[relation.keyFrom]) {
+            objsByKeys[relation.keyFrom] = {};
+            for (var j = 0; j < objs.length; j++) {
+                if (!objsByKeys[relation.keyFrom][objs[j][relation.keyFrom]]) {
+                    objsByKeys[relation.keyFrom][objs[j][relation.keyFrom]] = [];
+                }
+                objsByKeys[relation.keyFrom][objs[j][relation.keyFrom]].push(objs[j]);
+            }
+            keyVals[relation.keyFrom] = Object.keys(objsByKeys[relation.keyFrom]);
+        }
+        req['where'][relation.keyTo] = {inq: keyVals[relation.keyFrom]};
+        req['include'] = subInclude;
+        return function(cb) {
+            relation.model.all(req, function(err, dataIncluded) {
+
+                var objsIncluded = dataIncluded.map(function (obj) {
+                    return self.fromDatabase(relation.model.modelName, obj);
+                });
+
+                for (var i = 0; i < objsIncluded.length; i++) {
+                    var objectsFrom = objsByKeys[relation.keyFrom][objsIncluded[i][relation.keyTo]];
+                    for (var j = 0; j < objectsFrom.length; j++) {
+                        if (!objectsFrom[j].__cache) {
+                            objectsFrom[j].__cache = {};
+                        }
+                        if (relation.type == 'hasMany') {
+                            if (!objectsFrom[j].__cache[relationName]) {
+                                objectsFrom[j].__cache[relationName] = [];
+                            }
+                            objectsFrom[j].__cache[relationName].push(objsIncluded[i]);
+                        } else {
+                            objectsFrom[j].__cache[relationName] = objsIncluded[i];
+                        }
+                    }
+                }
+                cb(err, dataIncluded);
+            });
+        };
+    }
+    */
+}
+
 /**
  * Return string representation of class
  *
@@ -671,6 +871,7 @@ AbstractClass.hasMany = function hasMany(anotherClass, params) {
         type: 'hasMany',
         keyFrom: 'id',
         keyTo: params['foreignKey'],
+        modelTo: anotherClass,
         multiple: true
     };
     // each instance of this class should have method named
@@ -744,6 +945,7 @@ AbstractClass.belongsTo = function (anotherClass, params) {
         type: 'belongsTo',
         keyFrom: params['foreignKey'],
         keyTo: 'id',
+        modelTo: anotherClass,
         multiple: false
     };
 
@@ -751,6 +953,10 @@ AbstractClass.belongsTo = function (anotherClass, params) {
     this.prototype['__finders__'] = this.prototype['__finders__'] || {};
 
     this.prototype['__finders__'][methodName] = function (id, cb) {
+        if (id === null) {
+            cb(null, null);
+            return;
+        }
         anotherClass.find(id, function (err,inst) {
             if (err) return cb(err);
             if (!inst) return cb(null, null);
diff --git a/lib/adapters/mysql.js b/lib/adapters/mysql.js
index 5d464029..f57977da 100644
--- a/lib/adapters/mysql.js
+++ b/lib/adapters/mysql.js
@@ -224,9 +224,20 @@ MySQL.prototype.all = function all(model, filter, callback) {
         if (err) {
             return callback(err, []);
         }
-        callback(null, data.map(function (obj) {
-            return self.fromDatabase(model, obj);
-        }));
+        var preprocessDataCallback = function(model, data) {
+            data.map(function (obj) {
+                return self.fromDatabase(model, obj);
+            });
+            return data;
+        };
+
+        var objs = preprocessDataCallback(model, data);
+        if (filter && filter.include) {
+            this._models[model].model.include(objs, filter.include, callback, preprocessDataCallback);
+        } else {
+            callback(null, objs);
+        }
+
     }.bind(this));
 
     return sql;