Let's start with Symfony's plug-in structure. In general, it consists of folders and files as follows:

sfPlugin/
  config/
    sfPluginConfiguration.class.php
    routing.yml
    doctrine/
     schema.yml
  lib/
    sfPlugin.class.php
    helper/
    filter/
    form/
    model/
    task/
  modules/
    pluginModule/
      actions/
      config/
      templates/
  web/

You can see that there is a strong similarity between this file structure and Symfony's application file structure. You don't need to create every directory, only those that you will need when making this plug-in. The /config directory contains all configuration files, such as routing.yml, that can be used for adding a module for routing. Schema and plug-in dependencies go to this folder, too. The /lib folder holds tasks, helpers, forms, models, and the main plug-in class. Inside /modules, all ready-to-use modules are kept; inside /web are all images, stylesheets, and JavaScripts.

As you want to develop your own plug-in, you will avoid the TCPDF plug-in mentioned in the introduction to this section and use an alternative: the Free PDF PHP (FPDF) general-purpose library.

For simple PDF creation, you don't have to code much; all you need is one simple helper with one exemplary function that will generate a PDF with text. You must have the FPDF library installed before creating this helper. You can download it from www.fpdf.org and copy it into the PHP libraries. Under Linux, you can also install it as a package. This helper file could look like this:

<?php
require('fpdf/fpdf.php');
function generatePDF() {
    $pdf=new FPDF();
    $pdf->AddPage();
    $pdf->SetFont('Times','B',12);
    $pdf->Cell(40,10,'Symfony FPDF Plugin');
    $pdf->Output();
}
?>
code snippet /symfony/plugins/sfFPDFPlugin-1.0.0/lib/helper/sfFPDFHelper.php

Plug-in development requires a few basic facts about the plug-in. This information is stored in the package.xml file in the root folder of the plug-in. An example is presented here:

<?xml version="1.0" encoding="UTF-8"?>
  <package xmlns="http://pear.php.net/dtd/package-2.0"
    xmlns:tasks="http://pear.php.net/dtd/tasks-1.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" packagerversion="1.8.0"
    version="2.0" xsi:schemaLocation="http://pear.php.net/dtd/tasks-1.0
    http://pear.php.net/dtd/tasks-1.0.xsd http://pear.php.net/dtd/package-2.0
    http://pear.php.net/dtd/package-2.0.xsd">
  <name>sfFPDFPlugin</name>
  <channel>pear.symfony-project.com</channel>
  <summary>Exemplary FPDF Plugin</summary>
  <description>Very short example</description>
  <lead>
    <name>Wrox</name>
    <user>Wrox</user>
    <email>foo_bar@wrox.com</email>
    <active>yes</active>
  </lead>
  <date>2011-02-27</date>
  <time>00:00:00</time>
  <version>
    <release>1.0.0</release>
    <api>1.0.0</api>
  </version>
  <stability>
    <release>stable</release>
    <api>stable</api>
  </stability>
  <license uri="http://www.symfony-project.com/license">MIT license</license>
  <notes>
    Exemplary notes
  </notes>
  <contents>
    <dir name="/">
      <file md5sum="2779dd4abdee0683069bc5ecb9721cde"

name="lib/helper/sfFPDFHelper.php" role="data"/>
    </dir>
  </contents>
  <dependencies>
    <required>
      <php>
        <min>5.3.0</min>
      </php>
      <pearinstaller>
        <min>1.4.1</min>
      </pearinstaller>
    </required>
  </dependencies>
  <phprelease/>
</package>
code snippet /symfony/plugins/sfFPDFPlugin-1.0.0/package.xml

Note that you can set the minimal version of PEAR and PHP as well as the plug-in's version and its stability. You need to supply the MD5 sum as well. This is a minimal security measure to counteract unauthorized file replacement and also helps with discovering corrupt file download.

The file structure of your plug-in should be as follows now:

sfFPDFPlugin-1.0.0\
    lib\
        helper\
            sfFPDFHelper.php
package.xml

To test your plug-in, all you have to do is to pack it into an archive and install it:

$ symfony plugin:install /home/wrox/public_html/sfFPDFPlugin-1.0.0.tar.gz

Although the directory path may differ on your machine, the output will be the same:

>> plugin installing plugin "/home/wrox/public_html/sfFPDFPlugin-1.0.0.tar.gz"
>> sfSymfonyPluginManager Installation successful for plugin
    "/home/wrox/public_html/sfFPDFPlugin-1.0.0.tar.gz"

Your helper can be now added into the configuration file of your applications. An example is presented here:

all:
    .settings:
       standard_helpers:    [Partial, Cache, sfFPDF]
code snippet /symfony/apps/frontend/config/settings.yml

And here is an example action that utilizes this helper:

public function executeIndex(sfWebRequest $request)
  {
    $response = $this->getResponse();
    $response->setContentType('application/pdf');
  }
code snippet /symfony/apps/frontend/modules/pdfexample/actions/actions.class.php

The preceding code sets the output type as PDF. You need to execute the helper in a view as follows:

<?php echo generatePDF(); ?>
code snippet /symfony/apps/frontend/modules/pdfexample/templates/indexSuccess.php

When the routing is set to call this action, you should see a PDF file like the one in Figure 11-1.

Figure 11.1. Symfony PDF plug-in output

When a copy of fpdf.php is in your /app/vendors/fpdf/ directory, you can proceed with the process of creating a CakePHP plug-in. Plug-ins in CakePHP are usually self-contained applications on their own, so the file structure for such a plug-in is nearly identical to those of a normal CakePHP application.

First you need to name your plug-in. For this example, pdfreport should be a good name. The basic plug-in file structure used for the pdfreport example plug-in looks as follows:

/pdfreport
    /app
    /plugins
    /pdfreport
    /controllers
    /models
    /views
    /pdfreport_app_controller.php
    /pdfreport_app_model.php

In the main plug-in folder, there are two important files: the pdfreport_app_controller.php file that is the plug-in's AppController and the pdfreport_app_model.php file that is the plug-in's AppModel. These files are named after plug-in's name.

To start building your plug-in, you need to create the file structure shown in the preceding section. The content of the AppController file of the plug-in in this example is a simple class extending the AppControler of your main application. The listing of this file is as follows:

<?php
    class PdfreportAppController extends AppController {
    }
?>
code snippet /cakephp/app/plugins/pdfreport/pdfreport_app_controller.php

The situation is similar with the AppModel of the plug-in. The code for this example is as follows:

<?php
    class PdfreportAppModel extends AppModel {
    }
?>
code snippet /cakephp/app/plugins/pdfreport/models/pdfreport_app_model.php

Now you have the basis of your plug-in, and it is time to create a controller that will handle all the capabilities of your plug-in. Since you want to generate PDF reports from your application, you need to create GeneratePdfController inside the /controllers folder of your plug-in. In this example, the controller file will prepare a user list that is stored in the addresses database table. To do this, you need to use the $uses variable to point out that this controller uses the Address model to read all the data. The controller file used in this example goes as follows:

<?php
class GeneratePdfController extends PdfreportAppController {

var $name = 'GeneratePdf';
    var $uses = array('Address');
    function index() {
        $this->layout = 'pdf';
        $this->set('address_list', $this->Address->find('all'));
    }
}
?>
code snippet /cakephp/app/plugins/pdfreport/controllers/pdfreport_app_controller.php

This controller file has an index() action that does two things: specify the layout file that was used to render the view file and read all data from the Address model and pass it to the view file as the address_list variable.

The layout file pdf.ctp, specified in the index action, needs to be created inside the /views/layouts folder. It will be used to render the index.ctp view file as PDF content instead of HTML content. The content of the layout file should be as follows:

<?php
    header("Content-type: application/pdf");
    echo $content_for_layout;
?>
code snippet /cakephp/app/plugins/pdfreport/views/layouts/pdf.ctp

You should create the model file and set the $useTable variable to false because this model does not use any database tables. Code for this file can go like this:

<?php
class GeneratePdf extends PdfreportAppModel {
    var $name = 'GeneratePdf';
    var $useTable = false;
}
?>
code snippet /cakephp/app/plugins/pdfreport/models/generate_pdf.php

Finally, the view file, index.ctp, needs to be created in the /app/plugins/pdfreport/views/generate_pdf folder. Here you will place all the PDF building commands, but first you need to import the FPDF library by using the App::import() command. The code used to illustrate how the PDF file is generated is listed next:

<?php
    App::import('Vendor', 'fpdf/fpdf');
    $pdf = new FPDF();
    $pdf->AddPage();
    $pdf->SetFont('Times', '', 16);
    $pdf->Write(5, 'Persons list');
    $pdf->Ln();
    $pdf->SetFontSize(10);

$pdf->Write(5, 'Report of users held in database.');
    $pdf->Ln();
    $pdf->Ln(5);
    $pdf->SetFont('Arial', 'i', 10);
    $pdf->Cell(10 ,7, 'Nr.', 1);
    $pdf->Cell(20 ,7, 'Name', 1);
    $pdf->Cell(50 ,7, 'Email', 1);
    $pdf->Cell(20 ,7, 'Phone', 1);
    $pdf->Ln();
    $pdf->SetFont('Helvetica', '', 10);
    foreach ( $address_list as $line ) {
    $address = $line['Address'];
        $pdf->Cell(10 ,7, $address['id'], 1);
        $pdf->Cell(20, 7, $address['first_name'].' '.$address['last_name'], 1);
        $pdf->Cell(50, 7, $address['email'], 1);
        $pdf->Cell(20, 7, $address['phone'], 1);
        $pdf->Ln();
    }
    $pdf->Output();
?>
code snippet /cakephp/app/views/addresses/index.ctp

If you wish to learn more on how PDF files are created, please visit http://fpdf.org/ because this example introduces only basic functions.

This concludes writing your CakePHP plug-in, and now you probably wonder how you can use it. Well, this is quite simple. Because this plug-in was designed to generate PDFs containing a user list, it would be nice to add this option to an application that has a user list already. For this example, the application from Chapter 4 will be used, but you need to add one code line at the end of the index.ctp file that is responsible for displaying the address list. It will create the Get pdf report link illustrated in Figure 11-2. The report is presented in Figure 11-3. The code line that needs to be added is as follows:

<?php echo $html->link('Get pdf report', array('plugin' => 'pdfreport',
    'controller' => 'GeneratePdf', 'action' => 'index')); ?>
code snippet /app/views/addresses/index.ctp

Figure 11.2. Address list in your application

Figure 11.3. The user list PDF report