$product = Mage::getModel('catalog/product')->load(1234); // Здесь 1234 - ID существующего продукта
$product->setName('My Product')->save();
На это получаю ошибку:
Warning: Invalid argument supplied for foreach() in /usr/share/nginx/http/app/code/core/Mage/Eav/Model/Entity/Abstract.php on line 1180
#0 /usr/share/nginx/http/app/code/core/Mage/Eav/Model/Entity/Abstract.php(1180): mageCoreErrorHandler(2, 'Invalid argumen...', '/usr/share/ngin...', 1180, Array)
#1 /usr/share/nginx/http/app/code/core/Mage/Eav/Model/Entity/Abstract.php(1123): Mage_Eav_Model_Entity_Abstract->_collectSaveData(Object(Df_Catalog_Model_Product))
#2 /usr/share/nginx/http/app/code/core/Mage/Core/Model/Abstract.php(318): Mage_Eav_Model_Entity_Abstract->save(Object(Df_Catalog_Model_Product))
#3 /usr/share/nginx/http/app/design/frontend/default/default/template/catalog/product/list.phtml(134): Mage_Core_Model_Abstract->save()