Zend_Form decorators: Unable to view error messages (validation)

Question

When we add decorators to the form elements in zend, the validation message doesn't shows why ?

Code Example :

$this->addElement('Text', 'Last_Name',array(
        //'decorators' => $this->elementDecoratorsTr,
        'label' => 'Last Name:',
        'required' => false,
        'filters' => array('StringTrim'),
            'validators' => array(array('validator' => 'StringLength','validator' => 'Alpha')) 
        ));

Answer 1

Here is Zend_Form_Element source code:

$decorators = $this->getDecorators();
if (empty($decorators)) {
    $this->addDecorator('ViewHelper')
        ->addDecorator('Errors')   // notice Errors decorator
        ->addDecorator('Description', array('tag' => 'p', 'class' => 'description'))
        ->addDecorator('HtmlTag', array('tag' => 'dd', 
                                        'id'  => $this->getName() . '-element'))
        ->addDecorator('Label', array('tag' => 'dt'));
}

If you set your own decorators then the default ones are not loaded.

In order to see validation messages you need to have an Errors decorator among the decorators you set.