Monday, September 23, 2013

phpcake - Getting Started

Getting Started

The CakePHP framework provides a robust base for your application. It can handle every aspect, from the user’s initial request all the way to the final rendering of a web page. And since the framework follows the principles of MVC, it allows you to easily customize and extend most aspects of your application.
The framework also provides a basic organizational structure, from filenames to database table names, keeping your entire application consistent and logical. This concept is simple but powerful. Follow the conventions and you’ll always know exactly where things are and how they’re organized.
The best way to experience and learn CakePHP is to sit down and build something. To start off we’ll build a simple blog application.

Blog Tutorial

Welcome to CakePHP. You’re probably checking out this tutorial because you want to learn more about how CakePHP works. It’s our aim to increase productivity and make coding more enjoyable: we hope you’ll see this as you dive into the code.
This tutorial will walk you through the creation of a simple blog application. We’ll be getting and installing Cake, creating and configuring a database, and creating enough application logic to list, add, edit, and delete blog posts.
Here’s what you’ll need:
  1. A running web server. We’re going to assume you’re using Apache, though the instructions for using other servers should be very similar. We might have to play a little with the server configuration, but most folks can get Cake up and running without any configuration at all. Make sure you have PHP 5.2.8 or greater.
  2. A database server. We’re going to be using MySQL server in this tutorial. You’ll need to know enough about SQL in order to create a database: Cake will be taking the reins from there. Since we’re using MySQL, also make sure that you have pdo_mysql enabled in PHP.
  3. Basic PHP knowledge. The more object-oriented programming you’ve done, the better: but fear not if you’re a procedural fan.
  4. Finally, you’ll need a basic knowledge of the MVC programming pattern. A quick overview can be found in Understanding Model-View-Controller. Don’t worry, it’s only a half a page or so.
Let’s get started!

Getting Cake

First, let’s get a copy of fresh Cake code.
To get a fresh download, visit the CakePHP project on GitHub: https://github.com/cakephp/cakephp/tags and download the latest release of 2.0
You can also clone the repository using git. git clone git://github.com/cakephp/cakephp.git
Regardless of how you downloaded it, place the code inside of your DocumentRoot. Once finished, your directory setup should look something like the following:
/path_to_document_root
    /app
    /lib
    /plugins
    /vendors
    .htaccess
    index.php
    README
Now might be a good time to learn a bit about how Cake’s directory structure works: check out the CakePHP Folder Structure section.

Creating the Blog Database

Next, let’s set up the underlying database for our blog. If you haven’t already done so, create an empty database for use in this tutorial, with a name of your choice. Right now, we’ll just create a single table to store our posts. We’ll also throw in a few posts right now to use for testing purposes. Execute the following SQL statements into your database:
/* First, create our posts table: */
CREATE TABLE posts (
    id INT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    title VARCHAR(50),
    body TEXT,
    created DATETIME DEFAULT NULL,
    modified DATETIME DEFAULT NULL
);

/* Then insert some posts for testing: */
INSERT INTO posts (title,body,created)
    VALUES ('The title', 'This is the post body.', NOW());
INSERT INTO posts (title,body,created)
    VALUES ('A title once again', 'And the post body follows.', NOW());
INSERT INTO posts (title,body,created)
    VALUES ('Title strikes back', 'This is really exciting! Not.', NOW());
The choices on table and column names are not arbitrary. If you follow Cake’s database naming conventions, and Cake’s class naming conventions (both outlined in CakePHP Conventions), you’ll be able to take advantage of a lot of free functionality and avoid configuration. Cake is flexible enough to accommodate even the worst legacy database schema, but adhering to convention will save you time.
Check out CakePHP Conventions for more information, but suffice it to say that naming our table ‘posts’ automatically hooks it to our Post model, and having fields called ‘modified’ and ‘created’ will be automagically managed by Cake.

Cake Database Configuration

Onward and upward: let’s tell Cake where our database is and how to connect to it. For many, this is the first and last time you configure anything.
A copy of CakePHP’s database configuration file is found in /app/Config/database.php.default. Make a copy of this file in the same directory, but name it database.php.
The config file should be pretty straightforward: just replace the values in the $default array with those that apply to your setup. A sample completed configuration array might look something like the following:
public $default = array(
    'datasource' => 'Database/Mysql',
    'persistent' => false,
    'host' => 'localhost',
    'port' => '',
    'login' => 'cakeBlog',
    'password' => 'c4k3-rUl3Z',
    'database' => 'cake_blog_tutorial',
    'schema' => '',
    'prefix' => '',
    'encoding' => 'utf8'
);
Once you’ve saved your new database.php file, you should be able to open your browser and see the Cake welcome page. It should also tell you that your database connection file was found, and that Cake can successfully connect to the database.
Note
Remember that you’ll need to have PDO, and pdo_mysql enabled in your php.ini.

Optional Configuration

There are three other items that can be configured. Most developers complete these laundry-list items, but they’re not required for this tutorial. One is defining a custom string (or “salt”) for use in security hashes. The second is defining a custom number (or “seed”) for use in encryption. The third item is allowing CakePHP write access to its tmp folder.
The security salt is used for generating hashes. Change the default salt value by editing /app/Config/core.php line 187. It doesn’t much matter what the new value is, as long as it’s not easily guessed:
/**
 * A random string used in security hashing methods.
 */
Configure::write('Security.salt', 'pl345e-P45s_7h3*S@l7!');
The cipher seed is used for encrypt/decrypt strings. Change the default seed value by editing /app/Config/core.php line 192. It doesn’t much matter what the new value is, as long as it’s not easily guessed:
/**
 * A random numeric string (digits only) used to encrypt/decrypt strings.
 */
Configure::write('Security.cipherSeed', '7485712659625147843639846751');
The final task is to make the app/tmp directory web-writable. The best way to do this is to find out what user your webserver runs as (<?php echo `whoami`; ?>) and change the ownership of the app/tmp directory to that user. The final command you run (in *nix) might look something like this:
$ chown -R www-data app/tmp
If for some reason CakePHP can’t write to that directory, you’ll be informed by a warning while not in production mode.

A Note on mod_rewrite

Occasionally a new user will run into mod_rewrite issues. For example if the CakePHP welcome page looks a little funny (no images or css styles), it probably means mod_rewrite isn’t functioning on your system. Please refer to one of the sections below about url rewriting for your webserver to get you up and running:
Now continue to Blog Tutorial - Adding a layer to start building your first CakePHP application.

Blog Tutorial - Adding a layer

Create a Post Model

The Model class is the bread and butter of CakePHP applications. By creating a CakePHP model that will interact with our database, we’ll have the foundation in place needed to do our view, add, edit, and delete operations later.
CakePHP’s model class files go in /app/Model, and the file we’ll be creating will be saved to /app/Model/Post.php. The completed file should look like this:
class Post extends AppModel {
}
Naming conventions are very important in CakePHP. By naming our model Post, CakePHP can automatically infer that this model will be used in the PostsController, and will be tied to a database table called posts.
Note
CakePHP will dynamically create a model object for you if it cannot find a corresponding file in /app/Model. This also means that if you accidentally name your file wrong (i.e. post.php or posts.php), CakePHP will not recognize any of your settings and will use the defaults instead.
For more on models, such as table prefixes, callbacks, and validation, check out the Models chapter of the Manual.

Create a Posts Controller

Next, we’ll create a controller for our posts. The controller is where all the business logic for post interaction will happen. In a nutshell, it’s the place where you play with the models and get post-related work done. We’ll place this new controller in a file called PostsController.php inside the /app/Controller directory. Here’s what the basic controller should look like:
class PostsController extends AppController {
    public $helpers = array('Html', 'Form');
}
Now, let’s add an action to our controller. Actions often represent a single function or interface in an application. For example, when users request www.example.com/posts/index (which is also the same as www.example.com/posts/), they might expect to see a listing of posts. The code for that action would look something like this:
class PostsController extends AppController {
    public $helpers = array('Html', 'Form');

    public function index() {
        $this->set('posts', $this->Post->find('all'));
    }
}
By defining function index() in our PostsController, users can now access the logic there by requesting www.example.com/posts/index. Similarly, if we were to define a function called foobar(), users would be able to access that at www.example.com/posts/foobar.
Warning
You may be tempted to name your controllers and actions a certain way to obtain a certain URL. Resist that temptation. Follow CakePHP conventions (plural controller names, etc.) and create readable, understandable action names. You can map URLs to your code using “routes” covered later on.
The single instruction in the action uses set() to pass data from the controller to the view (which we’ll create next). The line sets the view variable called ‘posts’ equal to the return value of the find('all') method of the Post model. Our Post model is automatically available at $this->Post because we’ve followed Cake’s naming conventions.
To learn more about Cake’s controllers, check out the Controllers chapter.

Creating Post Views

Now that we have our data flowing to our model, and our application logic and flow defined by our controller, let’s create a view for the index action we created above.
Cake views are just presentation-flavored fragments that fit inside an application’s layout. For most applications they’re HTML mixed with PHP, but they may end up as XML, CSV, or even binary data.
Layouts are presentation code that is wrapped around a view, and can be defined and switched between, but for now, let’s just use the default.
Remember in the last section how we assigned the ‘posts’ variable to the view using the set() method? That would hand down data to the view that would look something like this:
// print_r($posts) output:

Array
(
    [0] => Array
        (
            [Post] => Array
                (
                    [id] => 1
                    [title] => The title
                    [body] => This is the post body.
                    [created] => 2008-02-13 18:34:55
                    [modified] =>
                )
        )
    [1] => Array
        (
            [Post] => Array
                (
                    [id] => 2
                    [title] => A title once again
                    [body] => And the post body follows.
                    [created] => 2008-02-13 18:34:56
                    [modified] =>
                )
        )
    [2] => Array
        (
            [Post] => Array
                (
                    [id] => 3
                    [title] => Title strikes back
                    [body] => This is really exciting! Not.
                    [created] => 2008-02-13 18:34:57
                    [modified] =>
                )
        )
)
Cake’s view files are stored in /app/View inside a folder named after the controller they correspond to (we’ll have to create a folder named ‘Posts’ in this case). To format this post data in a nice table, our view code might look something like this
<!-- File: /app/View/Posts/index.ctp -->

<h1>Blog posts</h1>
<table>
    <tr>
        <th>Id</th>
        <th>Title</th>
        <th>Created</th>
    </tr>

    <!-- Here is where we loop through our $posts array, printing out post info -->

    <?php foreach ($posts as $post): ?>
    <tr>
        <td><?php echo $post['Post']['id']; ?></td>
        <td>
            <?php echo $this->Html->link($post['Post']['title'],
array('controller' => 'posts', 'action' => 'view', $post['Post']['id'])); ?>
        </td>
        <td><?php echo $post['Post']['created']; ?></td>
    </tr>
    <?php endforeach; ?>
    <?php unset($post); ?>
</table>
Hopefully this should look somewhat simple.
You might have noticed the use of an object called $this->Html. This is an instance of the CakePHP HtmlHelper class. CakePHP comes with a set of view helpers that make things like linking, form output, JavaScript and Ajax a snap. You can learn more about how to use them in Helpers, but what’s important to note here is that the link() method will generate an HTML link with the given title (the first parameter) and URL (the second parameter).
When specifying URLs in Cake, it is recommended that you use the array format. This is explained in more detail in the section on Routes. Using the array format for URLs allows you to take advantage of CakePHP’s reverse routing capabilities. You can also specify URLs relative to the base of the application in the form of /controller/action/param1/param2.
At this point, you should be able to point your browser to http://www.example.com/posts/index. You should see your view, correctly formatted with the title and table listing of the posts.
If you happened to have clicked on one of the links we created in this view (that link a post’s title to a URL /posts/view/some_id), you were probably informed by CakePHP that the action hasn’t yet been defined. If you were not so informed, either something has gone wrong, or you actually did define it already, in which case you are very sneaky. Otherwise, we’ll create it in the PostsController now:
class PostsController extends AppController {
    public $helpers = array('Html', 'Form');

    public function index() {
         $this->set('posts', $this->Post->find('all'));
    }

    public function view($id = null) {
        if (!$id) {
            throw new NotFoundException(__('Invalid post'));
        }

        $post = $this->Post->findById($id);
        if (!$post) {
            throw new NotFoundException(__('Invalid post'));
        }
        $this->set('post', $post);
    }
}
The set() call should look familiar. Notice we’re using findById() rather than find('all') because we only really want a single post’s information.
Notice that our view action takes a parameter: the ID of the post we’d like to see. This parameter is handed to the action through the requested URL. If a user requests /posts/view/3, then the value ‘3’ is passed as $id.
We also do a bit of error checking to ensure a user is actually accessing a record. If a user requests /posts/view, we will throw a NotFoundException and let the CakePHP ErrorHandler take over. We also perform a similar check to make sure the user has accessed a record that exists.
Now let’s create the view for our new ‘view’ action and place it in /app/View/Posts/view.ctp
<!-- File: /app/View/Posts/view.ctp -->

<h1><?php echo h($post['Post']['title']); ?></h1>

<p><small>Created: <?php echo $post['Post']['created']; ?></small></p>

<p><?php echo h($post['Post']['body']); ?></p>
Verify that this is working by trying the links at /posts/index or manually requesting a post by accessing /posts/view/1.

Adding Posts

Reading from the database and showing us the posts is a great start, but let’s allow for the adding of new posts.
First, start by creating an add() action in the PostsController:
class PostsController extends AppController {
    public $helpers = array('Html', 'Form', 'Session');
    public $components = array('Session');

    public function index() {
        $this->set('posts', $this->Post->find('all'));
    }

    public function view($id) {
        if (!$id) {
            throw new NotFoundException(__('Invalid post'));
        }

        $post = $this->Post->findById($id);
        if (!$post) {
            throw new NotFoundException(__('Invalid post'));
        }
        $this->set('post', $post);
    }

    public function add() {
        if ($this->request->is('post')) {
            $this->Post->create();
            if ($this->Post->save($this->request->data)) {
                $this->Session->setFlash(__('Your post has been saved.'));
                return $this->redirect(array('action' => 'index'));
            }
            $this->Session->setFlash(__('Unable to add your post.'));
        }
    }
}
Note
You need to include the SessionComponent - and SessionHelper - in any controller where you will use it. If necessary, include it in your AppController.
Here’s what the add() action does: if the HTTP method of the request was POST, try to save the data using the Post model. If for some reason it doesn’t save, just render the view. This gives us a chance to show the user validation errors or other warnings.
Every CakePHP request includes a CakeRequest object which is accessible using $this->request. The request object contains useful information regarding the request that was just received, and can be used to control the flow of your application. In this case, we use the CakeRequest::is() method to check that the request is a HTTP POST request.
When a user uses a form to POST data to your application, that information is available in $this->request->data. You can use the pr() or debug() functions to print it out if you want to see what it looks like.
We use the SessionComponent’s SessionComponent::setFlash() method to set a message to a session variable to be displayed on the page after redirection. In the layout we have SessionHelper::flash which displays the message and clears the corresponding session variable. The controller’s Controller::redirect function redirects to another URL. The param array('action' => 'index') translates to URL /posts i.e the index action of posts controller. You can refer to Router::url() function on the API to see the formats in which you can specify a URL for various Cake functions.
Calling the save() method will check for validation errors and abort the save if any occur. We’ll discuss how those errors are handled in the following sections.

Data Validation

Cake goes a long way in taking the monotony out of form input validation. Everyone hates coding up endless forms and their validation routines. CakePHP makes it easier and faster.
To take advantage of the validation features, you’ll need to use Cake’s FormHelper in your views. The FormHelper is available by default to all views at $this->Form.
Here’s our add view:
<!-- File: /app/View/Posts/add.ctp -->

<h1>Add Post</h1>
<?php
echo $this->Form->create('Post');
echo $this->Form->input('title');
echo $this->Form->input('body', array('rows' => '3'));
echo $this->Form->end('Save Post');
?>
Here, we use the FormHelper to generate the opening tag for an HTML form. Here’s the HTML that $this->Form->create() generates:
<form id="PostAddForm" method="post" action="/posts/add">
If create() is called with no parameters supplied, it assumes you are building a form that submits to the current controller’s add() action (or edit() action when id is included in the form data), via POST.
The $this->Form->input() method is used to create form elements of the same name. The first parameter tells CakePHP which field they correspond to, and the second parameter allows you to specify a wide array of options - in this case, the number of rows for the textarea. There’s a bit of introspection and automagic here: input() will output different form elements based on the model field specified.
The $this->Form->end() call generates a submit button and ends the form. If a string is supplied as the first parameter to end(), the FormHelper outputs a submit button named accordingly along with the closing form tag. Again, refer to Helpers for more on helpers.
Now let’s go back and update our /app/View/Posts/index.ctp view to include a new “Add Post” link. Before the <table>, add the following line:
<?php echo $this->Html->link(
    'Add Post',
    array('controller' => 'posts', 'action' => 'add')
); ?>
You may be wondering: how do I tell CakePHP about my validation requirements? Validation rules are defined in the model. Let’s look back at our Post model and make a few adjustments:
class Post extends AppModel {
    public $validate = array(
        'title' => array(
            'rule' => 'notEmpty'
        ),
        'body' => array(
            'rule' => 'notEmpty'
        )
    );
}
The $validate array tells CakePHP how to validate your data when the save() method is called. Here, I’ve specified that both the body and title fields must not be empty. CakePHP’s validation engine is strong, with a number of pre-built rules (credit card numbers, email addresses, etc.) and flexibility for adding your own validation rules. For more information on that setup, check the Data Validation.
Now that you have your validation rules in place, use the app to try to add a post with an empty title or body to see how it works. Since we’ve used the FormHelper::input() method of the FormHelper to create our form elements, our validation error messages will be shown automatically.

Editing Posts

Post editing: here we go. You’re a CakePHP pro by now, so you should have picked up a pattern. Make the action, then the view. Here’s what the edit() action of the PostsController would look like:
public function edit($id = null) {
    if (!$id) {
        throw new NotFoundException(__('Invalid post'));
    }

    $post = $this->Post->findById($id);
    if (!$post) {
        throw new NotFoundException(__('Invalid post'));
    }

    if ($this->request->is('post') || $this->request->is('put')) {
        $this->Post->id = $id;
        if ($this->Post->save($this->request->data)) {
            $this->Session->setFlash(__('Your post has been updated.'));
            return $this->redirect(array('action' => 'index'));
        }
        $this->Session->setFlash(__('Unable to update your post.'));
    }

    if (!$this->request->data) {
        $this->request->data = $post;
    }
}
This action first ensures that the user has tried to access an existing record. If they haven’t passed in an $id parameter, or the post does not exist, we throw a NotFoundException for the CakePHP ErrorHandler to take care of.
Next the action checks that the request is a POST request. If it is, then we use the POST data to update our Post record, or kick back and show the user validation errors.
If there is no data set to $this->request->data, we simply set it to the previously retrieved post.
The edit view might look something like this:
<!-- File: /app/View/Posts/edit.ctp -->

<h1>Edit Post</h1>
<?php
echo $this->Form->create('Post');
echo $this->Form->input('title');
echo $this->Form->input('body', array('rows' => '3'));
echo $this->Form->input('id', array('type' => 'hidden'));
echo $this->Form->end('Save Post');
?>
This view outputs the edit form (with the values populated), along with any necessary validation error messages.
One thing to note here: CakePHP will assume that you are editing a model if the ‘id’ field is present in the data array. If no ‘id’ is present (look back at our add view), Cake will assume that you are inserting a new model when save() is called.
You can now update your index view with links to edit specific posts:
<!-- File: /app/View/Posts/index.ctp  (edit links added) -->

<h1>Blog posts</h1>
<p><?php echo $this->Html->link("Add Post", array('action' => 'add')); ?></p>
<table>
    <tr>
        <th>Id</th>
        <th>Title</th>
        <th>Action</th>
        <th>Created</th>
    </tr>

<!-- Here's where we loop through our $posts array, printing out post info -->

<?php foreach ($posts as $post): ?>
    <tr>
        <td><?php echo $post['Post']['id']; ?></td>
        <td>
            <?php echo $this->Html->link($post['Post']['title'], array('action' => 'view', $post['Post']['id'])); ?>
        </td>
        <td>
            <?php echo $this->Html->link('Edit', array('action' => 'edit', $post['Post']['id'])); ?>
        </td>
        <td>
            <?php echo $post['Post']['created']; ?>
        </td>
    </tr>
<?php endforeach; ?>

</table>

Deleting Posts

Next, let’s make a way for users to delete posts. Start with a delete() action in the PostsController:
public function delete($id) {
    if ($this->request->is('get')) {
        throw new MethodNotAllowedException();
    }

    if ($this->Post->delete($id)) {
        $this->Session->setFlash(__('The post with id: %s has been deleted.', h($id)));
        return $this->redirect(array('action' => 'index'));
    }
}
This logic deletes the post specified by $id, and uses $this->Session->setFlash() to show the user a confirmation message after redirecting them on to /posts. If the user attempts to do a delete using a GET request, we throw an Exception. Uncaught exceptions are captured by CakePHP’s exception handler, and a nice error page is displayed. There are many built-in Exceptions that can be used to indicate the various HTTP errors your application might need to generate.
Because we’re just executing some logic and redirecting, this action has no view. You might want to update your index view with links that allow users to delete posts, however:
<!-- File: /app/View/Posts/index.ctp -->

<h1>Blog posts</h1>
<p><?php echo $this->Html->link('Add Post', array('action' => 'add')); ?></p>
<table>
    <tr>
        <th>Id</th>
        <th>Title</th>
        <th>Actions</th>
        <th>Created</th>
    </tr>

<!-- Here's where we loop through our $posts array, printing out post info -->

    <?php foreach ($posts as $post): ?>
    <tr>
        <td><?php echo $post['Post']['id']; ?></td>
        <td>
            <?php echo $this->Html->link($post['Post']['title'], array('action' => 'view', $post['Post']['id'])); ?>
        </td>
        <td>
            <?php echo $this->Form->postLink(
                'Delete',
                array('action' => 'delete', $post['Post']['id']),
                array('confirm' => 'Are you sure?'));
            ?>
            <?php echo $this->Html->link('Edit', array('action' => 'edit', $post['Post']['id'])); ?>
        </td>
        <td>
            <?php echo $post['Post']['created']; ?>
        </td>
    </tr>
    <?php endforeach; ?>

</table>
Using postLink() will create a link that uses Javascript to do a POST request deleting our post. Allowing content to be deleted using GET requests is dangerous, as web crawlers could accidentally delete all your content.
Note
This view code also uses the FormHelper to prompt the user with a JavaScript confirmation dialog before they attempt to delete a post.

Routes

For some, CakePHP’s default routing works well enough. Developers who are sensitive to user-friendliness and general search engine compatibility will appreciate the way that CakePHP’s URLs map to specific actions. So we’ll just make a quick change to routes in this tutorial.
For more information on advanced routing techniques, see Routes Configuration.
By default, CakePHP responds to a request for the root of your site (i.e. http://www.example.com) using its PagesController, rendering a view called “home”. Instead, we’ll replace this with our PostsController by creating a routing rule.
Cake’s routing is found in /app/Config/routes.php. You’ll want to comment out or remove the line that defines the default root route. It looks like this:
Router::connect('/', array('controller' => 'pages', 'action' => 'display', 'home'));
This line connects the URL ‘/’ with the default CakePHP home page. We want it to connect with our own controller, so replace that line with this one:
Router::connect('/', array('controller' => 'posts', 'action' => 'index'));
This should connect users requesting ‘/’ to the index() action of our PostsController.
Note
CakePHP also makes use of ‘reverse routing’ - if with the above route defined you pass array('controller' => 'posts', 'action' => 'index') to a function expecting an array, the resultant URL used will be ‘/’. It’s therefore a good idea to always use arrays for URLs as this means your routes define where a URL goes, and also ensures that links point to the same place too.

Conclusion

Creating applications this way will win you peace, honor, love, and money beyond even your wildest fantasies. Simple, isn’t it? Keep in mind that this tutorial was very basic. CakePHP has many more features to offer, and is flexible in ways we didn’t wish to cover here for simplicity’s sake. Use the rest of this manual as a guide for building more feature-rich applications.
Now that you’ve created a basic Cake application you’re ready for the real thing. Start your own project, read the rest of the Cookbook and API.
If you need help, there are many ways to get the help you need - please see the Where to Get Help page. Welcome to CakePHP!
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