Validating input created by Javascript with Zend_Form

Yes there is.

most credits go to jeremy kendall see http://www.jeremykendall.net/2009/01/19/dynamically-adding-elements-to-zend-form/

The way i solved it is by doing a jquery/ajax call to a action which adds get a form element something like:

$.ajax({
    type : "POST",
    url : "/<controller>/addfield/",
    success : function(newElements) {
        // Insert new element before the submit button
        $("#productsNew-submit-element").before(newElements);
    }
});

What this does is it call a action that generates a form element and returns the html which you can then add

public function addfieldAction()
{
    //use $ajaxContext = $this->_helper->getHelper('AjaxContext'); in the init to make it return html via ajax

    $element = new Zend_Form_Element_Text("extraElement_1");
    $element->setBelongsTo("yourForm");
    $element->setLabel('myElementName');

    /*
    set other stuff like decorators or so
    */

    //now create the html 
    $elements .= $element->__toString();

    $this->view->fields = $elements;
}

After that you will get a new element in your form via ajax

Now when you submit you have to do that again but then pre validation

1. first check if your form has extraElements if so add them again
2. fill the add element with the posted value
3. validate

public function saveAction()
{
    function findFields($field) {
        // return field names that include 'extraElement_'
        if (strpos($field, 'extraElement_') !== false) {
            return $field;
        }
    }

    //set all stuff you need especially the form

    if($this->getRequest()->isPost()) {
        $postValues = $this->getRequest()->getPost();

        //step 1 
        $extraFields = array_filter(array_keys(current($postValues)), 'findFields');

        //add the element before validation
        if(count($extraFields) !== 0) {
            foreach(extraFields as $extraField) {
                $this->addFields($postValues[$extraField]); <-- step 2 add the field(s)
            }
        }

        //step 3 validate
        if($this->_form->isValid($postValues)) {
            //do post validation stuff
        } else {
            //show errors
        }
    }       
}