可捕获致命错误：类Zend \ Form \ View \ Helper \ FormLabel [关闭]的对象

Catchable fatal error: Object of class Zend\Form\View\Helper\FormLabel could not be converted to string in (...)\module\Application\view\application\produtos\form.phtml on line 2

form.phtml

<?php echo $this->form()->openTag($form);?>
<?php echo $this->formLabel($form->get('nome_produto'));?>
<?php echo $this->formElement($form->get('nome_produto'));?>
<?php echo $this->formErrors($form->get('nome_produto'));?>
<?php echo $this->form()->closeTag($form);?>

ProdutosController.php

public function novoAction()
{
    $form = new ProdutoForm();

    $view = new ViewModel(array(
            'form' => $form
    ));
    $view->setTemplate('application/produtos/form.phtml');
    return $view;
}

ProdutoForm.php

    <?php

namespace Application\Form;

use Zend\Form\Form;
use Zend\Form\Element\Text;

class ProdutoForm extends Form
{
public function __construct($name = null) {
    parent::__construct('produto');

    $nome = new Text('nome_produto');
    $nome->setLabel('Nome: ')
         ->setAttributes(array(
            'class' => 'input-mediun'
         ));
    $this->add($nome);

...

Yeah those form view helpers should really have better error detection. I'm guessing $form->get('nome_produto') is returning null. As a result the FormLabel view helper is simply returning itself since it has nothing to actually render. The echo command is then trying to cast the view helper to a string.

Double check the element name and make sure you're getting the right item from the form.