diff --git a/lib/dao.js b/lib/dao.js
index e7d08012..1c18853c 100644
--- a/lib/dao.js
+++ b/lib/dao.js
@@ -230,7 +230,7 @@ DataAccessObject.upsert = DataAccessObject.updateOrCreate = function upsert(data
         this.dataSource.connector.updateOrCreate(Model.modelName, inst.toObject(true), function (err, data) {
             var obj;
             if (data) {
-                inst._initProperties(data, true);
+                inst._initProperties(data, false);
                 obj = inst;
             } else {
                 obj = null;
@@ -327,7 +327,7 @@ DataAccessObject.findById = function find(id, cb) {
                 setIdValue(this, data, id);
             }
             obj = new this();
-            obj._initProperties(data, true);
+            obj._initProperties(data, false);
         }
         cb(err, obj);
     }.bind(this));
@@ -426,7 +426,7 @@ DataAccessObject.find = function find(params, cb) {
             data.forEach(function (d, i) {
                 var obj = new constr();
 
-                obj._initProperties(d, true, params.fields);
+                obj._initProperties(d, false, params.fields);
                 
                 if (params && params.include && params.collect) {
                     data[i] = obj.__cachedRelations[params.collect];
@@ -620,7 +620,7 @@ DataAccessObject.prototype.save = function (options, callback) {
                     if (err) {
                         return callback(err, inst);
                     }
-                    inst._initProperties(data, true);
+                    inst._initProperties(data, false);
                     updateDone.call(inst, function () {
                         saveDone.call(inst, function () {
                             callback(err, inst);
diff --git a/lib/model-builder.js b/lib/model-builder.js
index bf6995c6..a449bebf 100644
--- a/lib/model-builder.js
+++ b/lib/model-builder.js
@@ -267,7 +267,9 @@ ModelBuilder.prototype.define = function defineClass(className, properties, sett
             return this.__dataWas && this.__dataWas[attr];
         });
 
-        Object.defineProperty(ModelClass.prototype, '_' + attr, {
+        // FIXME: [rfeng] Do we need to keep the raw data?
+        // Use $ as the prefix to avoid conflicts with properties such as _id
+        Object.defineProperty(ModelClass.prototype, '$' + attr, {
             get: function () {
                 return this.__data && this.__data[attr];
             },
diff --git a/lib/model.js b/lib/model.js
index 3c228e39..9c7f48f3 100644
--- a/lib/model.js
+++ b/lib/model.js
@@ -100,7 +100,16 @@ ModelBaseClass.prototype._initProperties = function (data, applySetters) {
 
     if (applySetters === true) {
         Object.keys(data).forEach(function (attr) {
-            if((attr in properties) || (attr in ctor.relations) || strict === false) {
+            if((attr in properties) || (attr in ctor.relations)) {
+                self[attr] = self.__data[attr] || data[attr];
+            }
+        });
+    }
+
+    // Set the unknown properties as properties to the object
+    if(strict === false) {
+        Object.keys(data).forEach(function (attr) {
+            if(!(attr in properties)) {
                 self[attr] = self.__data[attr] || data[attr];
             }
         });