How to add an error message to the form in Zend Framework 2?

Question

I have a complex Zend\Form with multiple nested Fieldsets. Now I need to implement a cross-Fieldset-validation. That means, the validation rule refers to multiple Elements from different Fieldsets. The only way I found to do that, is to implement this validation in MyForm#isValid(), since it's the single place, where I can access every Fieldset from.

MyForm extends Form
{
    public function isValid()
    {
        $isFormValid = parent::isValid();
        $isCrossFieldsetVaidationOk = // my additional validation logic
        return $isFormValid && $isCrossFieldsetVaidationOk;
    }
}

Not tested yet, but it will work. The problem is in adding of error messages.

I've tried

$this->setMessages(array_merge(
    $this->getMessages(), ['my new message'])
);

But it doesn't work.

How can I add Form error messages?

Answer 1

Errors messages are link to the form's elements, not directly to the form. So as newage said, you have to set the message for a specific element (so his answer is valid and I upvoted it :-) ).

But as you extends Form, you can set you own error messages method directly in the form :

MyForm extends Form
{

    protected $errorMessages = [];

    public function isValid()
    {
        $isFormValid = parent::isValid();
        $isCrossFieldsetValidationOk = // your additional validation logic

        if (!$isCrossFieldsetValidationOk) {
            $this->addErrorMessage('Oh oh... Cross-fieldset validation error...');
        }
        return $isFormValid && $isCrossFieldsetValidationOk;
    }

    public function addErrorMessage($text)
    {
        $this->errorMessages[] = $text ;
        return $this; // For a fluent setter
    }

    public function getErrorMessages()
    {
        return $this->errorMessages ;
    }

    public function getMessages($elementName = null)
    {
        if ($elementName) {
            $messages = parent::getMessages($elementName);
        } else {
            $messages = array_merge($this->getErrorMessages(), parent::getMessages($elementName));
        }
        return $messages;
    }

}