Zend - New Record (DbAdapter)

<?php
$db          = Zend_Db_Table::getDefaultAdapter();
$entityTable = new Model_{name}();
$form        = new Backend_Form_{name}();

if ($this->_request->isPost()) {
    if ($form->isValid($this->_request->getPost())) {
        Zend_Db_Table::getDefaultAdapter()->beginTransaction();

        $entity = $entityTable->fetchNew();
        $entity->field1 = $form->getValue('field_name');
        .....
        $entity->save(); // insert

        //
        $entity->save(); // update

        Zend_Db_Table::getDefaultAdapter()->commit();
    } else
        $form->populate($this->_request->getPost());
} else {
    $form->populate ($entity->toArrayy());
}

/**
 * Entity ClassA
 */
class Model_EntityA extends Application_Db_Table_Abstract {
    protected $_name     = 'table_name';
    protected $_primary  = 'id';
    protected $_rowClass = 'Application_Db_Table_Row';
    protected $_dependentTables = array(
        'Model_EntityA',
        'Model_EntityM'
    );
}

/*
 * Class to handle ManyToMany
 */
class Model_EntityM extends Application_Db_Table_Abstract {
    protected $_name     = 'table_name';
    protected $_primary  = 'id';
    protected $_rowClass = 'Application_Db_Table_Row';
    protected $_referenceMap = array(
        'boutique' => array(
        'columns'       => 'a_id',
        'refTableClass' => 'Model_EntityA',
        'refColumns'    => 'id'
        ),
        'produit' => array(
            'columns'       => 'b_id',
            'refTableClass' => 'Model_EntityB',
            'refColumns'    => 'id'
        )
    );
}