How to create modular MVC components in Zend Frame

Question

I've been having problems created modular reusable components in my Zend Framework app. In this case I'm not referring to Zend Framework modules but rather the ability to have a reusable MVC widgety thing if you like. The problems I'm having may be very particular to my implementation, but I'm completely happy to throw it out and start again if someone can point me in the right direction. Anyway, specifics and code will hopefully explain things better and even if what I'm doing is not the best way it should show what I'm trying to achieve:

A simple example is a Mailing List sign up form. I want to include this on several pages of the site which use different Controllers and this presents a few problems in how to process the data and return relevant messages. I don't want to do either of the following as they really smell:

1. Create a base controller with the form processing in and extend (Bad)
2. Duplicate form processing code in relevant controllers (Even worse!)

The clean way to go feels to me to create a new Controller to process the mailing list form data, use a View Helper to easily output the form and relevant markup into the desired pages and then redirect back to the page where signup occurred once the form has been processed. However, I'd like to use the form validation provided by Zend_Form, which means I'd need to pass the form object back to the view helper somehow if validation fails but in the same request. I'm currently doing this by setting it as a variable on the view and then forwarding back to the previous page rather than redirecting, which is ok(ish). If validation is ok then I'd prefer to use a redirect back to the original page. I'm having trouble doing this though as I'd like to pass messages back to the component about the state of signup. Normally I'd use the FlashMessenger Action Helper, I could namespace it in this case so messages didn't clash with other page data, but I can't access it from within a View Helper. So currently I'm forwarding in this case too. I'd much prefer a redirect to prevent form resubmissions if a user refreshes the page and to keep the URL clean. I realise I essentially want to have a mini MVC dispatch process within a page and I think that's what the action stack is for? I really don't know much about this though and any pointers would be greatly appreciated. Here's my current code:

Controller:

<?php
class MailingListController extends Zend_Controller_Action {

    public function insertAction() {
        $request = $this->getRequest();
        $returnTo = $request->getParam('return_to');

        if(!$request->isPost() || (!isset($returnTo) || empty($returnTo))) {
            $this->_redirect('/');
        }

        $mailingList = new Model_MailingList();
        $form = new Form_MailingList();

        $returnTo = explode('/', $returnTo);

        if($form->isValid($_POST)) {
            $emailAddress = $form->getValue('email_address');

            $mailingList->addEmailAddress($emailAddress);

            $this->view->mailingListMessages = $mailingList->getMessages();
            $this->view->mailingListForm = "";
        }
        else {
            $this->view->mailingListForm = $form;
        }

        $this->_forward($returnTo[2], $returnTo[1], $returnTo[0]);
    }
}

return_to is a string containing the current URI (module/controller/action), which is generated in the View Helper. I'd prefer to redirect inside the $form->isValid($_POST) block.

View Helper:

<?php
class Zend_View_Helper_MailingList extends Zend_View_Helper_Abstract {

    public function mailingList($form, $messages = "") {
        if(!isset($form)) {
            $request = Zend_Controller_Front::getInstance()->getRequest();
            $currentPage = $request->getModuleName() . '/' . $request->getControllerName() . '/' . $request->getActionName();

            $form = new Form_MailingList();
            $form->setAction('/mailing-list/insert');
            $form->setCurrentPage($currentPage);
        }

        $html = '<div class="mailingList"><h2>Join Our Mailing List</h2>' . $form;
        $html .= $messages;
        $html .= '</div>';

        return $html;
    }

}

Getting an instance of the Front Controller in the View Helper isn't ideal but I'd prefer to encapsulate as much as possible.

If I have a form object where validation has failed I can pass it back into the helper to output with error messages. If I have some messages to render I can also pass them into the helper.

In my view scripts I'm using the helper like so:

<?=$this->mailingList($this->mailingListForm, $this->mailingListMessages);?>

If neither mailingListForm or mailingListMessages has been set on the view by MailingListController, it will output a new form with no messages.

Any help is greatly appreciated!

Answer 1

I think the way you've done it is pretty close to what I would do. If you set aside the requirement of wanting to display the Zend_Form error messages in the page, then what you do instead is:

• The view helper just displays the form (it doesn't need to take the form object or messages as parameters)
• The form submits to your other controller as it does now
• The mailing list controller redirects (instead of forwarding) back to the return URL on success
• The mailing list controller redisplays the form on its own, along with errors on failure

This makes everything much simpler, the only issue is that if there are any validation errors then the user loses their context and gets a plain old page with the form on instead of where they were. You can then address this (either now or at a later date) by changing the form to submit via. Ajax instead, and rendering the errors via. JS. But this would be a fair amount of work.

Answer 2

Using ajax seems to be an optimal way. View Action Helper is used only for the first load of the mailing form.

Controller

class MailingListController extends Zend_Controller_Action {

public function insertAction() {
    $request = $this->getRequest();

    $form = new Form_MailingList();

    if ($request->isPost()) {
        if ($form->isValid($request->getPost())) {
            $mailingList = new Model_MailingList();
            $emailAddress = $form->getValue('email_address');
            $mailingList->addEmailAddress($emailAddress);
            $form = $mailingList->getMessages();
        }
    }

    $this->view->form = $form;
}

}

view script insert.phtml

<?php echo $this->form; ?>

Form class

class Form_MailingList extends Zend_Form {

public function init() {
    //among other things
    $this->setAttrib('id', 'mailing-list-form');
    $this->setAction('/mailing-list/insert');
}

}

View Helper

class Zend_View_Helper_MailingList extends Zend_View_Helper_Abstract {

public function mailingList() {
    $this->view->headScript()->appendFile('/js/mailing-list.js');
    return '<div id="mailing-list-wrap">' . $this->view->action('insert', 'mailing-list') . '</div>';
}

}

JS file mailing-list.js

$(document).ready(function() {
    $('#mailing-list-form').submit(function() {
        var formAction = $(this).attr('action');
        var formData = $(this).serialize();

        $.post(formAction, formData, function(data) {
            //response going in form's parent container
            $(this).parent().html(data);
        });

        return false;
    });
});

Answer 3

OK, I've come up with a solution that I feel happier about and solves some of the problems I was facing. Hopefully, this might help someone out who's facing similar issues. The only downside now is that I'm referencing the Model inside the View Helper. Not loose coupling I know but I've seen this done several times before and it's even recommended in the ZF docs as a way to avoid using the 'action' view helper (which will create a new MVC dispatch loop). On the whole, I think the DRYness and encapsulation is worth it, there's probably some other suitable lingo too.

In order to be able to use a redirect back from my MailingListController but maintain the messages from my model and any form validation errors I need to store them in the session. For messages I'd normally use the FlashMessenger action helper, but as getting hold of this in a View Helper is not best practice, it won't handle my form errors and all it's really doing is saving stuff to the session anyway it's unnecessary. I can implement my own session storage in the Model_MailingList, which I can also use for the form errors. I can then repopulate the form with the errors after the redirect and print out any relevant messages. Anyway, here's the code:

Controller:

<?php

class MailingListController extends Zend_Controller_Action {

    public function insertAction() {
        $request = $this->getRequest();
        $returnTo = $request->getParam('return_to');

        if(!$request->isPost() || (!isset($returnTo) || empty($returnTo))) {
            $this->_redirect('/');
        }

        $mailingList = new Model_MailingList();
        $form = new Form_MailingList();

        if($form->isValid($_POST)) {
            $emailAddress = $form->getValue('email_address');
            $mailingList->addEmailAddress($emailAddress);
        }
        else {
            $mailingList->setFormErrors($form->getMessages());
        }

        $redirect = rtrim($request->getBaseUrl(), '/') . $returnTo;
        $this->_redirect($redirect);
    }
}

I've added a method to my Model_MailingList class; setFormErrors($errors) that I pass the error messages from the form if it fails validation. This saves the error array to the session.

I normally use a base model class that has addMessage and getMessages methods. These just access a protected array of messages. In my Model_MailingList I override these methods to store the messages in the session instead. In the addEmailAddress($emailAddress) method I'm already calling addMessage to say whether inserting the email address to the db has been successful.

Model:

<?php

class Model_MailingList extends Thinkjam_Model_DbAbstract {

    private $_session;

    public function __construct() {
        $this->_session = new Zend_Session_Namespace(__CLASS__);
    }

    public function setFormErrors($errors) {
        $this->_session->formErrors = $errors;
    }

    public function getFormErrors() {
        $errors = array();

        if(isset($this->_session->formErrors)) {
            $errors = $this->_session->formErrors;
            unset($this->_session->formErrors);
        }

        return $errors;
    }

    // override addMessage and getMessages

    protected function addMessage($message) {
        if(!isset($this->_session->messages)) {
            $this->_session->messages = array();
        }
        $this->_session->messages[] = $message;
    }

    public function getMessages() {
        if(isset($this->_session->messages)) {
            $this->_messages = $this->_session->messages;
            unset($this->_session->messages);
        }

        return $this->_messages;
    }

    …

    public function addEmailAddress($emailAddress) {
        ...

        // I call this if db insert was successful: 
        $this->addMessage("Thank you. You have been successfully added to the mailing list.")
    }
}

I now don't need to pass any params to the view helper as it can query it's state from the Model directly. $this->view->messenger is just another view helper that converts an array to an unordered list.

View Helper:

<?php

class Zend_View_Helper_MailingList extends Zend_View_Helper_Abstract {

    private $_mailingList;

    public function MailingList() {
        $this->_mailingList = new Model_MailingList();
        return $this;
    }

    public function getForm() {
        $request = Zend_Controller_Front::getInstance()->getRequest();
        $currentPage = '/' . $request->getModuleName() . '/' . $request->getControllerName() . '/' . $request->getActionName();

        $form = new Form_MailingList();
        $form->setAction('/mailing-list/insert');
        $form->setCurrentPage($currentPage);
        $form->setErrors($this->_mailingList->getFormErrors());

        $html = '<div class="mailingList"><h2>Join Our Mailing List</h2>' . $form;
        $html .= $this->view->messenger($this->_mailingList->getMessages());
        $html .= '</div>';

        return $html;
    }

}

Then in the Form_MailingList class I just need to add an additional method to repopulate the error messages. Although getMessages() is a method of Zend_Form there doesn't appear to be any corresponding setMessages(). You can do this on a Zend_Form_Element however, so I've added the following function to the Form_MailingList class:

Form:

<?php

class Form_MailingList extends Thinkjam_Form_Abstract {

    ...

    public function setErrors(array $errors) {
        foreach($errors as $key => $value) {
            $this->getElement($key)->setErrors($value);
        }
    }

}

I can now add a signup form on any page of my site using the MailingList view helper:

<?=$this->MailingList()->getForm();?>

I realise a lot of the problems I was facing was down to a very specific set of circumstances, but hopefully this can help some other people out in some way!

Cheers, Alex