diff --git a/core/lib/Thelia/Form/CartAdd.php b/core/lib/Thelia/Form/CartAdd.php
new file mode 100644
index 000000000..3522d8f83
--- /dev/null
+++ b/core/lib/Thelia/Form/CartAdd.php
@@ -0,0 +1,134 @@
+<?php
+/*************************************************************************************/
+/*                                                                                   */
+/*      Thelia	                                                                     */
+/*                                                                                   */
+/*      Copyright (c) OpenStudio                                                     */
+/*      email : info@thelia.net                                                      */
+/*      web : http://www.thelia.net                                                  */
+/*                                                                                   */
+/*      This program is free software; you can redistribute it and/or modify         */
+/*      it under the terms of the GNU General Public License as published by         */
+/*      the Free Software Foundation; either version 3 of the License                */
+/*                                                                                   */
+/*      This program is distributed in the hope that it will be useful,              */
+/*      but WITHOUT ANY WARRANTY; without even the implied warranty of               */
+/*      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the                */
+/*      GNU General Public License for more details.                                 */
+/*                                                                                   */
+/*      You should have received a copy of the GNU General Public License            */
+/*	    along with this program. If not, see <http://www.gnu.org/licenses/>.         */
+/*                                                                                   */
+/*************************************************************************************/
+namespace Thelia\Form;
+
+use Propel\Runtime\ActiveQuery\Criteria;
+use Symfony\Component\Validator\Constraints;
+use Symfony\Component\Validator\ExecutionContextInterface;
+use Thelia\Action\Exception\CombinationNotFoundException;
+use Thelia\Action\Exception\ProductNotFoundException;
+use Thelia\Model\Base\StockQuery;
+use Thelia\Model\ProductQuery;
+
+class CartAdd extends BaseForm
+{
+
+    /**
+     *
+     * in this function you add all the fields you need for your Form.
+     * Form this you have to call add method on $this->formBuilder attribute :
+     *
+     * $this->formBuilder->add("name", "text")
+     *   ->add("email", "email", array(
+     *           "attr" => array(
+     *               "class" => "field"
+     *           ),
+     *           "label" => "email",
+     *           "constraints" => array(
+     *               new \Symfony\Component\Validator\Constraints\NotBlank()
+     *           )
+     *       )
+     *   )
+     *   ->add('age', 'integer');
+     *
+     * @return null
+     */
+    protected function buildForm()
+    {
+        $this->formBuilder
+            ->add("product", "hidden", array(
+                "constraints" => array(
+                    new Constraints\NotBlank(),
+                    new Constraints\Callback(array(
+                        "methods" => array($this, "checkProduct")
+                    ))
+                )
+            ))
+            ->add("combination", "hidden", array(
+                "constraints" => array(
+                    new Constraints\Callback(array(
+                        "methods" => array($this, "checkCombination")
+                    ))
+                )
+
+            ))
+            ->add("quantity", "text", array(
+                "constraints" => array(
+                    new Constraints\NotBlank(),
+                    new Constraints\Callback(array(
+                        "methods" => array($this, "checkStock")
+                    ))
+                )
+            ))
+            ->add("append", "hidden")
+            ->add("newness", "hidden")
+        ;
+    }
+
+    protected function checkProduct($value, ExecutionContextInterface $context)
+    {
+        $product = ProductQuery::create()->findPk($value);
+
+        if (is_null($product)) {
+            throw new ProductNotFoundException(sprintf("this product id does not exists : %d", $value));
+        }
+    }
+
+    protected function checkCombination($value, ExecutionContextInterface $context)
+    {
+        if ($value) {
+            $data = $context->getRoot()->getData();
+
+            $stock = StockQuery::create()
+                ->filterByProductId($data["product"])
+                ->filterByCombinationId($value, Criteria::EQUAL)
+                ->findOne();
+
+            if (is_null($stock)) {
+                throw new CombinationNotFoundException(sprintf("This combination id does not exists for this product : %d", $value));
+            }
+        }
+    }
+
+    protected function checkStock($value, ExecutionContextInterface $context)
+    {
+        $data = $context->getRoot()->getData();
+
+        $product = ProductQuery::create()->findPk($data["product"]);
+
+        if ($product) {
+             if(false === $product->stockIsValid($value, $data["combination"])) {
+                $context->addViolation("quantity value is not valid");
+             }
+        }
+
+    }
+
+    /**
+     * @return string the name of you form. This name must be unique
+     */
+    public function getName()
+    {
+        return "thelia_cart_add";
+    }
+}
\ No newline at end of file