Editing and Deleting Data

In the previous chapter we've come to learn how we can use the zend-form and zend-db components for creating new data-sets. This chapter will focus on finalizing the CRUD functionality by introducing the concepts for editing and deleting data.

Binding Objects to Forms

The one fundamental difference between our "add post" and "edit post" forms is the existence of data. This means we need to find a way to get data from our repository into the form. Luckily, zend-form provides this via a data-binding feature.

In order to use this feature, you will need to retrieve a Post instance, and bind it to the form. To do this, we will need to:

We'll begin by updating the WriteController:

The final result will look like the following:

<?php
// In module/Blog/src/Controller/WriteController.php:

namespace Blog\Controller;

use Blog\Form\PostForm;
use Blog\Model\Post;
use Blog\Model\PostCommandInterface;
use Blog\Model\PostRepositoryInterface;
use InvalidArgumentException;
use Zend\Mvc\Controller\AbstractActionController;
use Zend\View\Model\ViewModel;

class WriteController extends AbstractActionController
{
    /**
     * @var PostCommandInterface
     */
    private $command;

    /**
     * @var PostForm
     */
    private $form;

    /**
     * @var PostRepositoryInterface
     */
    private $repository;

    /**
     * @param PostCommandInterface $command
     * @param PostForm $form
     * @param PostRepositoryInterface $repository
     */
    public function __construct(
        PostCommandInterface $command,
        PostForm $form,
        PostRepositoryInterface $repository
    ) {
        $this->command = $command;
        $this->form = $form;
        $this->repository = $repository;
    }

    public function addAction()
    {
        $request   = $this->getRequest();
        $viewModel = new ViewModel(['form' => $this->form]);

        if (! $request->isPost()) {
            return $viewModel;
        }

        $this->form->setData($request->getPost());

        if (! $this->form->isValid()) {
            return $viewModel;
        }

        $post = $this->form->getData();

        try {
            $post = $this->command->insertPost($post);
        } catch (\Exception $ex) {
            // An exception occurred; we may want to log this later and/or
            // report it to the user. For now, we'll just re-throw.
            throw $ex;
        }

        return $this->redirect()->toRoute(
            'blog/detail',
            ['id' => $post->getId()]
        );
    }

    public function editAction()
    {
        $id = $this->params()->fromRoute('id');
        if (! $id) {
            return $this->redirect()->toRoute('blog');
        }

        try {
            $post = $this->repository->findPost($id);
        } catch (InvalidArgumentException $ex) {
            return $this->redirect()->toRoute('blog');
        }

        $this->form->bind($post);
        $viewModel = new ViewModel(['form' => $this->form]);

        $request = $this->getRequest();
        if (! $request->isPost()) {
            return $viewModel;
        }

        $this->form->setData($request->getPost());

        if (! $this->form->isValid()) {
            return $viewModel;
        }

        $post = $this->command->updatePost($post);
        return $this->redirect()->toRoute(
            'blog/detail',
            ['id' => $post->getId()]
        );
    }
}

The primary differences between addAction() and editAction() are that the latter needs to first fetch a Post, and this post is bound to the form. By binding it, we ensure that the data is populated in the form for the initial display, and, once validated, the same instance is updated. This means that we can omit the call to getData() after validating the form.

Now we need to update our WriteControllerFactory. First, add a new import statement to it:

// In module/Blog/src/Factory/WriteControllerFactory.php:
use Blog\Model\PostRepositoryInterface;

Next, update the body of the factory to read as follows:

// In module/Blog/src/Factory/WriteControllerFactory.php:
public function __invoke(ContainerInterface $container, $requestedName, array $options = null)
{
    $formManager = $container->get('FormElementManager');

    return new WriteController(
        $container->get(PostCommandInterface::class),
        $formManager->get(PostForm::class),
        $container->get(PostRepositoryInterface::class)
    );
}

The controller and model are now wired together, so it's time to turn to routing.

Adding the edit route

The edit route is identical to the blog/detail route we previously defined, with two exceptions:

Update the 'blog' child_routes to add the new route:

// In module/Blog/config/module.config.php:

use Zend\Router\Http\Segment;

return [
    'service_manager' => [ /* ... */ ],
    'controllers'     => [ /* ... */ ],
    'router'          => [
        'routes' => [
            'blog' => [
                /* ... */

                'child_routes' => [
                    /* ... */

                    'edit' => [
                        'type' => Segment::class,
                        'options' => [
                            'route'    => '/edit/:id',
                            'defaults' => [
                                'controller' => Controller\WriteController::class,
                                'action'     => 'edit',
                            ],
                            'constraints' => [
                                'id' => '[1-9]\d*',
                            ],
                        ],
                    ],
                ],
            ],
        ],
    ],
    'view_manager'    => [ /* ... */ ],
];

Creating the edit template

Rendering the form remains essentially the same between the add and edit templates; the only difference between them is the form action. As such, we will create a new partial script for the form, update the add template to use it, and create a new edit template.

Create a new file, module/Blog/view/blog/write/form.phtml, with the following contents:

<?php
$form = $this->form;
$fieldset = $form->get('post');

$title = $fieldset->get('title');
$title->setAttribute('class', 'form-control');
$title->setAttribute('placeholder', 'Post title');

$text = $fieldset->get('text');
$text->setAttribute('class', 'form-control');
$text->setAttribute('placeholder', 'Post content');

$submit = $form->get('submit');
$submit->setValue($this->submitLabel);
$submit->setAttribute('class', 'btn btn-primary');

$form->prepare();

echo $this->form()->openTag($form);
?>

<fieldset>
<div class="form-group">
    <?= $this->formLabel($title) ?>
    <?= $this->formElement($title) ?>
    <?= $this->formElementErrors()->render($title, ['class' => 'help-block']) ?>
</div>

<div class="form-group">
    <?= $this->formLabel($text) ?>
    <?= $this->formElement($text) ?>
    <?= $this->formElementErrors()->render($text, ['class' => 'help-block']) ?>
</div>
</fieldset>

<?php
echo $this->formSubmit($submit);
echo $this->formHidden($fieldset->get('id'));
echo $this->form()->closeTag();

Now, update the add template, module/Blog/view/write/add.phtml to read as follows:

<h1>Add a blog post</h1>

<?php
$form = $this->form;
$form->setAttribute('action', $this->url());
echo $this->partial('blog/write/form', [
    'form' => $form,
    'submitLabel' => 'Insert new post',
]);

The above retrieves the form, sets the form action, provides a context-appropriate label for the submit button, and renders it with our new partial view script.

Next in line is the creation of the new template, blog/write/edit:

<h1>Edit blog post</h1>

<?php
$form = $this->form;
$form->setAttribute('action', $this->url('blog/edit', [], true));
echo $this->partial('blog/write/form', [
    'form' => $form,
    'submitLabel' => 'Update post',
]);

The three differences between the add and edit templates are:

Because the URI requires the identifier, we need to ensure the identifier is passed. The way we've done this in the controllers is to pass the identifier as a parameter: $this->url('blog/edit/', ['id' => $id]). This would require that we pass the original Post instance or the identifier we pull from it to the view, however. zend-router allows another option, however: you can tell it to re-use currently matched parameters. This is done by setting the last parameter of the view-helper to true: $this->url('blog/edit', [], true).

If you try and update the post, it'll be successful, but you'll notice that no edits were saved! Why? Because we have not yet implemented the functionality in our command class. Let's do that now.

Edit the file module/Blog/src/Model/ZendDbSqlCommand.php, and update the updatePost() method to read as follows:

public function updatePost(Post $post)
{
    if (! $post->getId()) {
        throw new RuntimeException('Cannot update post; missing identifier');
    }

    $update = new Update('posts');
    $update->set([
            'title' => $post->getTitle(),
            'text' => $post->getText(),
    ]);
    $update->where(['id = ?' => $post->getId()]);

    $sql = new Sql($this->db);
    $statement = $sql->prepareStatementForSqlObject($update);
    $result = $statement->execute();

    if (! $result instanceof ResultInterface) {
        throw new RuntimeException(
            'Database error occurred during blog post update operation'
        );
    }

    return $post;
}

This looks very similar to the insertPost() implementation we did earlier. The primary difference is the usage of the Update class; instead of calling a values() method on it, we call:

Additionally, we test for the presence of an identifier before performing the operation, and, because we already have one, and the Post submitted to us contains all the edits we submitted to the database, we return it verbatim on success.

Implementing the delete functionality

Last but not least, it's time to delete some data. We start this process by implementing the deletePost() method in our ZendDbSqlCommand class:

// In module/Blog/src/Model/ZendDbSqlCommand.php:

public function deletePost(Post $post)
{
    if (! $post->getId()) {
        throw new RuntimeException('Cannot update post; missing identifier');
    }

    $delete = new Delete('posts');
    $delete->where(['id = ?' => $post->getId()]);

    $sql = new Sql($this->db);
    $statement = $sql->prepareStatementForSqlObject($delete);
    $result = $statement->execute();

    if (! $result instanceof ResultInterface) {
        return false;
    }

    return true;
}

The above uses Zend\Db\Sql\Delete to create the SQL necessary to delete the post with the given identifier, which we then execute.

Next, let's create a new controller, Blog\Controller\DeleteController, in a new file module/Blog/src/Controller/DeleteController.php, with the following contents:

<?php
namespace Blog\Controller;

use Blog\Model\Post;
use Blog\Model\PostCommandInterface;
use Blog\Model\PostRepositoryInterface;
use InvalidArgumentException;
use Zend\Mvc\Controller\AbstractActionController;
use Zend\View\Model\ViewModel;

class DeleteController extends AbstractActionController
{
    /**
     * @var PostCommandInterface
     */
    private $command;

    /**
     * @var PostRepositoryInterface
     */
    private $repository;

    /**
     * @param PostCommandInterface $command
     * @param PostRepositoryInterface $repository
     */
    public function __construct(
        PostCommandInterface $command,
        PostRepositoryInterface $repository
    ) {
        $this->command = $command;
        $this->repository = $repository;
    }

    public function deleteAction()
    {
        $id = $this->params()->fromRoute('id');
        if (! $id) {
            return $this->redirect()->toRoute('blog');
        }

        try {
            $post = $this->repository->findPost($id);
        } catch (InvalidArgumentException $ex) {
            return $this->redirect()->toRoute('blog');
        }

        $request = $this->getRequest();
        if (! $request->isPost()) {
            return new ViewModel(['post' => $post]);
        }

        if ($id != $request->getPost('id')
            || 'Delete' !== $request->getPost('confirm', 'no')
        ) {
            return $this->redirect()->toRoute('blog');
        }

        $post = $this->command->deletePost($post);
        return $this->redirect()->toRoute('blog');
    }
}

Like the WriteController, it composes both our PostRepositoryInterface and PostCommandInterface. The former is used to ensure we are referencing a valid post instance, and the latter to perform the actual deletion.

When a user requests the page via the GET method, we will display a page containing details of the post, and a confirmation form. When submitted, we'll check to make sure they confirmed the deletion before issuing our delete command. If any conditions fail, or on a successful deletion, we redirect to our blog listing page.

Like the other controllers, we now need a factory. Create the file module/Blog/src/Factory/DeleteControllerFactory.php with the following contents:

<?php
namespace Blog\Factory;

use Blog\Controller\DeleteController;
use Blog\Model\PostCommandInterface;
use Blog\Model\PostRepositoryInterface;
use Interop\Container\ContainerInterface;
use Zend\ServiceManager\Factory\FactoryInterface;

class DeleteControllerFactory implements FactoryInterface
{
    /**
     * @param ContainerInterface $container
     * @param string $requestedName
     * @param null|array $options
     * @return DeleteController
     */
    public function __invoke(ContainerInterface $container, $requestedName, array $options = null)
    {
        return new DeleteController(
            $container->get(PostCommandInterface::class),
            $container->get(PostRepositoryInterface::class)
        );
    }
}

We'll now wire this into the application, mapping the controller to its factory, and providing a new route. Open the file module/Blog/config/module.config.php and make the following edits.

First, map the controller to its factory:

'controllers' => [
    'factories' => [
        Controller\ListController::class => Factory\ListControllerFactory::class,
        Controller\WriteController::class => Factory\WriteControllerFactory::class,
        // Add the following line:
        Controller\DeleteController::class => Factory\DeleteControllerFactory::class,
    ],
],

Now add another child route to our "blog" route:

'router' => [
    'routes' => [
        'blog' => [
            /* ... */

            'child_routes' => [
                /* ... */

                'delete' => [
                    'type' => Segment::class,
                    'options' => [
                        'route' => '/delete/:id',
                        'defaults' => [
                            'controller' => Controller\DeleteController::class,
                            'action'     => 'delete',
                        ],
                        'constraints' => [
                            'id' => '[1-9]\d*',
                        ],
                    ],
                ],
            ],
        ],
    ],
],

Finally, we'll create a new view script, module/Blog/view/blog/delete/delete.phtml, with the following contents:

<h1>Delete post</h1>

<p>Are you sure you want to delete the following post?</p>

<ul class="list-group">
    <li class="list-group-item"><?= $this->escapeHtml($this->post->getTitle()) ?></li>
</ul>

<form action="<?php $this->url('blog/delete', [], true) ?>" method="post">
    <input type="hidden" name="id" value="<?= $this->escapeHtmlAttr($this->post->getId()) ?>" />
    <input class="btn btn-default" type="submit" name="confirm" value="Cancel" />
    <input class="btn btn-danger" type="submit" name="confirm" value="Delete" />
</form>

This time around, we're not using zend-form; as it consists of just a hidden element and cancel/confirm buttons, there's no need to provide an OOP model for it.

From here, you can now visit one of the existing blog posts, e.g., http://localhost:8080/blog/delete/1 to see the form. If you choose Cancel, you should be taken back to the list; if you choose Delete, it should delete the post and then take you back to the list, and you should see the post is no longer present.

Making the list more useful

Our blog post list currently lists everything about all of our blog posts; additionally, it doesn't link to them, which means we have to manually update the URL in our browser in order to test functionality. Let's update the list view to be more useful; we'll:

In a real-world application, we'd probably use some sort of access controls to determine if the edit and delete links will be displayed; we'll leave that for another tutorial, however.

Open your module/Blog/view/blog/list/index.phtml file, and update it to read as follows:

<h1>Blog Posts</h1>

<div class="list-group">
<?php foreach ($this->posts as $post): ?>
  <div class="list-group-item">
    <h4 class="list-group-item-heading">
      <a href="<?= $this->url('blog/detail', ['id' => $post->getId()]) ?>">
        <?= $post->getTitle() ?>
      </a>
    </h4>

    <div class="btn-group" role="group" aria-label="Post actions">
      <a class="btn btn-xs btn-default" href="<?= $this->url('blog/edit', ['id' => $post->getId()]) ?>">Edit</a>
      <a class="btn btn-xs btn-danger" href="<?= $this->url('blog/delete', ['id' => $post->getId()]) ?>">Delete</a>
    </div>
  </div>    
<?php endforeach ?>
</div>

<div class="btn-group" role="group" aria-label="Post actions">
  <a class="btn btn-primary" href="<?= $this->url('blog/add') ?>">Write new post</a>
</div>

At this point, we have a far more functional blog, as we can move around between pages using links and buttons.

Summary

In this chapter we've learned how data binding within the zend-form component works, and used it to provide functionality for our update routine. We also learned how this allows us to de-couple our controllers from the details of how a form is structured, helping us keep implementation details out of our controller.

We also demonstrated the use of view partials, which allow us to split out duplication in our views and re-use them. In particular, we did this with our form, to prevent needlessly duplicating the form markup.

Finally, we looked at two more aspects of the Zend\Db\Sql subcomponent, and learned how to Update and Delete operations.

In the next chapter we'll summarize everything we've done. We'll talk about the design patterns we've used, and we'll cover several questions that likely arose during the course of this tutorial.