I’m the one of hosts of a Coding Dojo in my city called Katayunos. Katayunos is the mix of the word Kata (coding kata) and “Desayuno” (breakfast in Spanish). A group of brave programmers meet together one Saturday morning and after having breakfast we pick one coding kata and we practise TDD and pair programming. It’s something difficult to explain to non-geek people (why the hell we wake up early one Saturday morning to do this) but if you are reading this post probably it sounds good:).
My work as host is basically pick the place and encourage people to join to the Coding Dojo. One way of doing this (besides twitter buzz) is take my address book and send one bulk email to all of them inviting to join us. I don’t like this kind of mails. They look like spam, so I prefer to send a personalized email. This email has a common part (the place location, the hour, the event description, …) and the personalized part. I can do it manually, the list isn’t so huge, but definitely that’s not cool. Because of that I have done a little script to perform this operation. I can do a simple PHP script but we are speaking about announcing a event about TDD, SOLID and things like that, so I must use the “right way”. Let’s start.
I manage my list of contacts within a spreadsheet. In this spreadsheet I have the name, the email and a one paragraph with the personalized part to each one of my contact. I can easily export this spreadsheet to a csv document like this:
Peter Parker, spiderman@gmail.com, "Lorem ipsum dolor sit amet, ..." Clark Kent, superman@gmail.com, "consectetur adipisicing elit, ..." Juan López Fernández, superlopez@gmail.com, "sed do eiusmod tempor incididunt .."
So first of all I need to parse this file.
class Parser
{
private $data;
public function createFromCsvFile($path)
{
$handle = fopen($path, "r");
while (($data = fgetcsv($handle)) !== false) {
$this->data[] = [
'name' => trim($data[0]),
'email' => trim($data[1]),
'body' => isset($data[2]) ? trim($data[2]) : null,
];
}
}
public function getData()
{
return $this->data;
}
}
Easy. Now I want to send this parsed array by email. Because of that I will include Swiftmailer in my composer.json file.
My email will also be one template and one personalized part. We will use Twig to manage the template.
"require": {
"swiftmailer/swiftmailer": "v5.0.2",
"twig/twig": "v1.13.2",
}
Now we will create a class to wrap the needed code to send emails
class Mailer
{
private $swiftMailer;
private $swiftMessage;
function __construct(Swift_Mailer $swiftMailer, Swift_Message $swiftMessage)
{
$this->swiftMailer = $swiftMailer;
$this->swiftMessage = $swiftMessage;
}
public function sendMessage($to, $body)
{
$this->swiftMessage->setTo($to);
$this->swiftMessage->setBody(strip_tags($body));
$this->swiftMessage->addPart($body, 'text/html');
return $this->swiftMailer->send($this->swiftMessage);
}
}
Our Mailer class sends mails. Our Parser class parses one csv file. Now we need something to join those two classes: the Spammer class. Spammer class will take one parsed array and it will send one by one the mails using Mailer class.
class Spammer
{
private $twig;
private $mailer;
function __construct(Twig_Environment $twig, Mailer $mailer)
{
$this->twig = $twig;
$this->mailer = $mailer;
}
public function sendEmails($data)
{
foreach ($data as $item) {
$to = $item['email'];
$this->mailer->sendMessage($to, $this->twig->render('mail.twig', $item));
}
}
}
Ok with this three classes I can easily send my emails. This script is a console script and we also want pretty console colours and this kind of stuff. symfony/console to the rescue. But I’ve a problem now. I want to write one message when one mail is sent and another one when something wrong happens. If I want to do that I need to change my Spammer class. But my Spammer class does’t know anything about my console Command. If I inject the console command into my Spammer class I will violate the Demeter law, and that’s a sin. What can we do? Easy: The mediator pattern. We can write one implementation of mediator pattern but we also can use symfony/event-dispatcher, a well done implementation of this pattern. We change our Spammer class to:
use Symfony\Component\EventDispatcher\EventDispatcher;
class Spammer
{
private $twig;
private $mailer;
private $dispatcher;
function __construct(Twig_Environment $twig, Mailer $mailer, EventDispatcher $dispatcher)
{
$this->twig = $twig;
$this->mailer = $mailer;
$this->dispatcher = $dispatcher;
}
public function sendEmails($data)
{
foreach ($data as $item) {
$to = $item['email'];
try {
$this->mailer->sendMessage($to, $this->twig->render('mail.twig', $item));
$this->dispatcher->dispatch(MailEvent::EVENT_MAIL_SENT, new MailEvent\Sent($to));
} catch (\Exception $e) {
$this->dispatcher->dispatch(MailEvent::EVENT_SENT_ERROR, new MailEvent\Error($to, $e));
}
}
}
}
Now can easily build of console command class:
use Symfony\Component\Console\Command\Command;
use Symfony\Component\Console\Input\InputArgument;
use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Input\InputOption;
use Symfony\Component\Console\Output\OutputInterface;
use Symfony\Component\EventDispatcher\EventDispatcher;
class SpamCommand extends Command
{
private $parser;
private $dispatcher;
protected function configure()
{
$this->setName('spam:run')
->setDescription('Send Emails');
}
protected function execute(InputInterface $input, OutputInterface $output)
{
$output->writeln("Sending mails ...");
$this->dispatcher->addListener(MailEvent::EVENT_MAIL_SENT, function (MailEvent\Sent $event) use ($output) {
$output->writeln("<info>Mail sent to</info>: <fg=black;bg=cyan>{$event->getTo()}</fg=black;bg=cyan>");
}
);
$this->dispatcher->addListener(MailEvent::EVENT_SENT_ERROR, function (MailEvent\Error $event) use ($output) {
$output->writeln("<error>Error sending mail to</error>: <fg=black;bg=cyan>{$event->getTo()}</fg=black;bg=cyan> Error: " . $event->getException()->getMessage());
}
);
$this->spammer->sendEmails($this->parser->getData());
$output->writeln("End");
}
public function setSpammer(Spammer $spammer)
{
$this->spammer = $spammer;
}
public function setParser(Parser $parser)
{
$this->parser = $parser;
}
public function setDispatcher(EventDispatcher $dispatcher)
{
$this->dispatcher = $dispatcher;
}
}
With all this parts we can build our script. Our classes are decoupled. That’s good but setting up the dependencies properly can be hard. Because of that we will use symfony/dependency-injection. With symfony DIC we can set up our dependency tree within a yaml file:
Our main services.yml
imports:
- resource: conf.yml
- resource: mail.yml
- resource: twig.yml
parameters:
base.path: .
services:
parser:
class: Parser
calls:
- [createFromCsvFile, [%mail.list%]]
mailer:
class: Mailer
arguments: [@swift.mailer, @swift.message]
spam.command:
class: SpamCommand
calls:
- [setParser, [@parser]]
- [setDispatcher, [@dispatcher]]
- [setSpammer, [@spammer]]
spammer:
class: Spammer
arguments: [@twig, @mailer, @dispatcher]
dispatcher:
class: Symfony\Component\EventDispatcher\EventDispatcher
I like to separate the configuration files to reuse those files between projects and to make them more readable.
One for twig:
parameters:
twig.path: %base.path%/templates
twig.conf:
auto_reload: true
services:
twigLoader:
class: Twig_Loader_Filesystem
arguments: [%twig.path%]
twig:
class: Twig_Environment
arguments: [@twigLoader, %twig.conf%]
another one for swiftmailer:
services:
swift.message:
class: Swift_Message
calls:
- [setSubject, [%mail.subject%]]
- [setFrom, [%mail.from.mail%: %mail.from.name%]]
swift.transport:
class: Swift_SmtpTransport
arguments: [%mail.smtp.host%, %mail.smtp.port%, %mail.smtp.encryption%]
calls:
- [setUsername, [%mail.smtp.username%]]
- [setPassword, [%mail.smtp.password%]]
swift.mailer:
class: Swift_Mailer
arguments: [@swift.transport]
and the last one for the configuration parameters:
parameters: mail.do.not.send.mails: false mail.list: %base.path%/mailList.csv mail.subject: mail subject mail.from.name: My Name mail.from.mail: my_email@mail.com mail.smtp.username: my_smtp_username mail.smtp.password: my_smtp_password mail.smtp.host: smtp.gmail.com mail.smtp.port: 465 mail.smtp.encryption: ssl
Now we can build our script.
use Symfony\Component\Console\Application;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\Config\FileLocator;
use Symfony\Component\DependencyInjection\Loader\YamlFileLoader;
$container = new ContainerBuilder();
$loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/conf'));
$loader->load('services.yml');
$container->setParameter('base.path', __DIR__);
$application = new Application();
$application->add($container->get('spam.command'));
$application->run();
n
And that’s all. My colleagues of the next Katayuno will be invited in a “SOLID” way :).
Source code is available in my github account.
BTW: Do you want to organize one Katayuno in your city? It’s very easy. Feel free to contact me for further information.
Gonzalo Ayuso - Web Architect 