Zend Framework 2

---

Now that we have the Album module set up with controller action 
methods and view scripts, it is time to look at the model section of 
our application. Remember that the model is the part that deals with 
the application’s core purpose (the so-called “business rules”) and, 
in our case, deals with the database. We will make use of the Zend 
Framework class Zend\Db\TableGateway\TableGateway which is 
used to find, insert, update and delete rows from a database table.
We are going to use MySQL, via PHP’s PDO driver, so create a 
database called zf2tutorial, and run these SQL statements to create 
the album table with some data in it.
	 CREATE TABLE album (
   id int(11) NOT NULL auto_increment,
   artist varchar(100) NOT NULL,
   title varchar(100) NOT NULL,
   PRIMARY KEY (id)
 );
 INSERT INTO album (artist, title)
     VALUES  ('The  Military  Wives',  'In  My  Dreams');
 INSERT INTO album (artist, title)
     VALUES  ('Adele',  '21');
 INSERT INTO album (artist, title)
     VALUES  ('Bruce  Springsteen',  'Wrecking Ball (Deluxe)');
 INSERT INTO album (artist, title)
     VALUES  ('Lana  Del  Rey',  'Born  To  Die');
 INSERT INTO album (artist, title)
     VALUES  ('Gotye',  'Making  Mirrors');
(The test data chosen happens to be the Bestsellers on Amazon UK 
at the time of writing!)
We now have some data in a database and can write a very simple 
model for it.
The model files
Zend Framework does not provide a Zend\Model component because
 the model is your business logic and it’s up to you to decide how you 
want it to work. There are many components that you can use for this
 depending on your needs. One approach is to have model classes
 represent each entity in your application and then use mapper objects 
that load and save entities to the database. Another is to use an 
Object-relational mapping (ORM) technology, such as Doctrine or Propel.
For this tutorial, we are going to create a very simple model by creating 
an AlbumTable class that uses the Zend\Db\TableGateway\TableGateway 
class in which each album object is an Album object (known as an entity). 
This is an implementation of the Table Data Gateway design pattern to 
allow for interfacing with data in a database table. Be aware though that the 
Table Data Gateway pattern can become limiting in larger systems. There is 
also a temptation to put database access code into controller action methods 
as these are exposed by Zend\Db\TableGateway\AbstractTableGateway. 
Don’t do this!
Let’s start by creating a file called Album.php under module/Album/src/Album/Model:
	 namespace Album\Model;

 class Album
 {
     public $id;
     public $artist;
     public $title;

     public function exchangeArray($data)
     {
         $this->id     = (!empty($data['id'])) ? $data['id'] : null;
         $this->artist = (!empty($data['artist'])) ? $data['artist'] : null;
         $this->title  = (!empty($data['title'])) ? $data['title'] : null;
     }
 }
Our Album entity object is a simple PHP class. In order to work with
 Zend\Db’s TableGateway class, we need to implement the exchangeArray() 
method. This method simply copies the data from the passed in array to our 
entity’s properties. We will add an input filter for use with our form later.
Next, we create our AlbumTable.php file in module/Album/src/Album/Model 
directory like this:
	 namespace Album\Model;

 use Zend\Db\TableGateway\TableGateway;

 class AlbumTable
 {
     protected $tableGateway;

     public function __construct(TableGateway $tableGateway)
     {
         $this->tableGateway = $tableGateway;
     }

     public function fetchAll()
     {
         $resultSet = $this->tableGateway->select();
         return $resultSet;
     }

     public function getAlbum($id)
     {
         $id  = (int) $id;
         $rowset = $this->tableGateway->select(array('id' => $id));
         $row = $rowset->current();
         if (!$row) {
             throw new \Exception("Could not find row $id");
         }
         return $row;
     }

     public function saveAlbum(Album $album)
     {
         $data = array(
             'artist' => $album->artist,
             'title'  => $album->title,
         );

         $id = (int) $album->id;
         if ($id == 0) {
             $this->tableGateway->insert($data);
         } else {
             if ($this->getAlbum($id)) {
                 $this->tableGateway->update($data, array('id' => $id));
             } else {
                 throw new \Exception('Album id does not exist');
             }
         }
     }

     public function deleteAlbum($id)
     {
         $this->tableGateway->delete(array('id' => (int) $id));
     }
 }
There’s a lot going on here. Firstly, we set the protected property 
$tableGateway to the TableGateway instance passed in the constructor.
 We will use this to perform operations on the database table for our albums.
We then create some helper methods that our application will use to 
interface with the table gateway. fetchAll() retrieves all albums rows from
the database as a ResultSet, getAlbum() retrieves a single row as an Album 
object, saveAlbum() either creates a new row in the database or updates a 
row that already exists and deleteAlbum() removes the row completely. The 
code for each of these methods is, hopefully, self-explanatory.
Using ServiceManager to configure the table gateway and inject into the 
AlbumTable
In order to always use the same instance of our AlbumTable, we will use the
 ServiceManager to define how to create one. This is most easily done in the
 Module class where we create a method called getServiceConfig() which is 
automatically called by the ModuleManager and applied to the ServiceManager. 
We’ll then be able to retrieve it in our controller when we need it.
To configure the ServiceManager, we can either supply the name of the class 
to be instantiated or a factory (closure or callback) that instantiates the object 
when the ServiceManager needs it. We start by implementing getServiceConfig() 
to provide a factory that creates an AlbumTable. Add this method to the bottom 
of the Module.php file in module/Album.
	 namespace Album;

 // Add these import statements:
 use Album\Model\Album;
 use Album\Model\AlbumTable;
 use Zend\Db\ResultSet\ResultSet;
 use Zend\Db\TableGateway\TableGateway;

 class Module
 {
     // getAutoloaderConfig() and getConfig() methods here

     // Add this method:
     public function getServiceConfig()
     {
         return array(
             'factories' => array(
                 'Album\Model\AlbumTable' =>  function($sm) {
                     $tableGateway = $sm->get('AlbumTableGateway');
                     $table = new AlbumTable($tableGateway);
                     return $table;
                 },
                 'AlbumTableGateway' => function ($sm) {
                     $dbAdapter = $sm->get('Zend\Db\Adapter\Adapter');
                     $resultSetPrototype = new ResultSet();
                     $resultSetPrototype->setArrayObjectPrototype(new Album());
                     return new TableGateway('album', $dbAdapter, null, $resultSetPrototype);
                 },
             ),
         );
     }
 }
This method returns an array of factories that are all merged together by the 
ModuleManager before passing them to the ServiceManager. The factory for 
Album\Model\AlbumTable uses the ServiceManager to create an 
AlbumTableGateway to pass to the AlbumTable. We also tell the ServiceManager
 that an AlbumTableGateway is created by getting a Zend\Db\Adapter\Adapter 
(also from the ServiceManager) and using it to create a TableGateway object. 
The TableGateway is told to use an Album object whenever it creates a new 
result row. The TableGateway classes use the prototype pattern for creation of 
result sets and entities. This means that instead of instantiating when required, 
the system clones a previously instantiated object. See PHP Constructor Best 
Practices and the Prototype Pattern for more details.
Finally, we need to configure the ServiceManager so that it knows how to get a 
Zend\Db\Adapter\Adapter. This is done using a factory called 
Zend\Db\Adapter\AdapterServiceFactory which we can configure within 
the merged config system. Zend Framework 2’s ModuleManager merges all 
the configuration from each module’s module.config.php file and then merges
 in the files in config/autoload (*.global.php and then *.local.php files). We’ll 
add our database configuration information to global.php which you should 
commit to your version control system. You can use local.php (outside of the 
VCS) to store the credentials for your database if you want to. 
Modify config/autoload/global.php (in the Zend Skeleton root, not inside
 the Album module) with following code:
	 return array(
     'db' => array(
         'driver'         => 'Pdo',
         'dsn'            => 'mysql:dbname=zf2tutorial;host=localhost',
         'driver_options' => array(
             PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES \'UTF8\''
         ),
     ),
     'service_manager' => array(
         'factories' => array(
             'Zend\Db\Adapter\Adapter'
                     => 'Zend\Db\Adapter\AdapterServiceFactory',
         ),
     ),
 );
You should put your database credentials in config/autoload/local.php so that 
they are not in the git repository (as local.php is ignored):
	 return array(
     'db' => array(
         'username' => 'YOUR USERNAME HERE',
         'password' => 'YOUR PASSWORD HERE',
     ),
 );
Back to the controller
Now that the ServiceManager can create an AlbumTable instance for us, we 
can add a method to the controller to retrieve it. Add getAlbumTable() to the 
AlbumController class:
	 // module/Album/src/Album/Controller/AlbumController.php:
     public function getAlbumTable()
     {
         if (!$this->albumTable) {
             $sm = $this->getServiceLocator();
             $this->albumTable = $sm->get('Album\Model\AlbumTable');
         }
         return $this->albumTable;
     }
You should also add:
1	 protected $albumTable;
to the top of the class.
We can now call getAlbumTable() from within our controller whenever we 
need to interact with our model.
If the service locator was configured correctly in Module.php, then we should 
get an instance of Album\Model\AlbumTable when calling getAlbumTable().
Listing albums
In order to list the albums, we need to retrieve them from the model and pass 
them to the view. To do this, we fill in indexAction() within AlbumController. 
Update the AlbumController’s indexAction() like this:
	 // module/Album/src/Album/Controller/AlbumController.php:
 // ...
     public function indexAction()
     {
         return new ViewModel(array(
             'albums' => $this->getAlbumTable()->fetchAll(),
         ));
     }
 // ...
With Zend Framework 2, in order to set variables in the view, we return a
ViewModel instance where the first parameter of the constructor is an array 
from the action containing data we need. These are then automatically 
assed to the view script. The ViewModel object also allows us to change 
the view script that is used, but the default is to use {controller name}/{action name}. 
We can now fill in the index.phtml view script:
	 <?php
 // module/Album/view/album/album/index.phtml:

 $title = 'My albums';
 $this->headTitle($title);
 ?>
 <h1><?php echo $this->escapeHtml($title); ?></h1>
 <p>
     <a href="<?php echo $this->url('album', array('action'=>'add'));?>">Add new album</a>
 </p>

 <table class="table">
 <tr>
     <th>Title</th>
     <th>Artist</th>
     <th> </th>
 </tr>
 <?php foreach ($albums as $album) : ?>
 <tr>
     <td><?php echo $this->escapeHtml($album->title);?></td>
     <td><?php echo $this->escapeHtml($album->artist);?></td>
     <td>
         <a href="<?php echo $this->url('album',
             array('action'=>'edit', 'id' => $album->id));?>">Edit</a>
         <a href="<?php echo $this->url('album',
             array('action'=>'delete', 'id' => $album->id));?>">Delete</a>
     </td>
 </tr>
 <?php endforeach; ?>
 </table>
The first thing we do is to set the title for the page (used in the layout) and also 
set the title for the <head> section using the headTitle() view helper which will 
display in the browser’s title bar. We then create a link to add a new album.
The url() view helper is provided by Zend Framework 2 and is used to create 
the links we need. The first parameter to url() is the route name we wish to use 
for construction of the URL, and the second parameter is an array of all the 
variables to fit into the placeholders to use. In this case we use our ‘album’
 route which is set up to accept two placeholder variables: action and id.
We iterate over the $albums that we assigned from the controller action.
 The Zend Framework 2 view system automatically ensures that these
 variables are extracted into the scope of the view script, so that we don’t
 have to worry about prefixing them with $this-> as we used to have to do 
with Zend Framework 1; however you can do so if you wish.
We then create a table to display each album’s title and artist, and provide
 links to allow for editing and deleting the record. A standard foreach: loop 
is used to iterate over the list of albums, and we use the alternate form 
using a colon and endforeach; as it is easier to scan than to try and match 
up braces. Again, the url() view helper is used to create the edit and delete links.
Note
We always use the escapeHtml() view helper to help protect ourselves from 
Cross Site Scripting (XSS) vulnerabilities (see 

 

                                    

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