Category Archives: PHP

Setting up PHP & MySQL on OS X Yosemite

It's that time again; Apple has shipped a new version of OS X, 10.10 Yosemite. Apple ships PHP 5.5.14 with Yosemite and this is how to set it up from a clean install.

However, if you don't want to use the built-in PHP or want to use version 5.6, then these are some alternatives:

Let's get started… Continue reading

Alias for the PHP built-in server

I keep forgetting the correct command line syntax for the PHP build-in server, so I've now made an alias for it in my .profile:

alias phps='php -S 0.0.0.0:8888'

Now I can simply type: phps public/index.php to start the built-in web server.

Throw an exception when simplexml_load_string fails

I keep having to look up how to stop the warning that are emitted when simplexml_load_string & simplexml_load_file fail, so this time I've written the world's simplest little class to take care of it for me from now on:

<?php

namespace Rka;

use UnexpectedValueException;

class Xml
{
    /**
     * Load an XML String and convert any warnings to an exception
     *
     * @param string  $string
     * @param string $class_name
     * @param int $options
     * @param string $ns
     * @param bool $is_prefix
     *
     * @throws UnexpectedValueException
     *
     * @return SimpleXMLElement
     */
    public static function loadXMLString(
        $string,
        $class_name = "SimpleXMLElement",
        $options = 0,
        $ns = "",
        $is_prefix = false
    ) {
        $previous = libxml_use_internal_errors(true);

        $xml = simplexml_load_string($string, $class_name, $options, $ns,
                 $is_prefix);

        if (!$xml) {
            $errors = self::getXMLErrorString();
            libxml_use_internal_errors($previous);
            throw new UnexpectedValueException($errors);
        }

        libxml_use_internal_errors($previous);
        return $xml;
    }

    /**
     * Load an XML File and convert any warnings to an exception
     *
     * @param string  $string
     * @param string $class_name
     * @param int $options
     * @param string $ns
     * @param bool $is_prefix
     *
     * @throws UnexpectedValueException
     *
     * @return SimpleXMLElement
     */
    public static function loadXMLFile(
        $string,
        $class_name = "SimpleXMLElement",
        $options = 0,
        $ns = "",
        $is_prefix = false
    ) {
        $previous = libxml_use_internal_errors(true);

        $xml = simplexml_load_file($string, $class_name, $options, $ns,
                 $is_prefix);

        if (!$xml) {
            $errors = self::getXMLErrorString();
            libxml_use_internal_errors($previous);
            throw new UnexpectedValueException($errors);
        }

        libxml_use_internal_errors($previous);
        return $xml;
    }

    /**
     * Helper method to format the XML errors into a string.
     *
     * @return string
     */
    protected static function getXMLErrorString()
    {
        $message = '';
        foreach (libxml_get_errors() as $error) {
            $message .= trim($error->message)
              . " on line: $error->line, column: $error->column.\n";
        }
        libxml_clear_errors();
        return trim($message);
    }
}

Update: The code has been updated based on the comments below. Thanks!

Redirecting in Slim Middleware

I recently ran into a problem with calling redirect() in a Slim framework middleware class, so I thought I'd better document the solution so that I remember in future!

The authentication middleware looks roughly like this:

class Authentication extends \Slim\Middleware
{
    public function call()
    {
        if (!$this->isLoggedIn()) {
            $app = \Slim\Slim::getInstance();
            $app->redirect($app->urlFor('login'));
        }

        $this->next->call();
    }

    // other methods...
}

The problem is that you can't call $app->redirect() in Middleware as redirect() is designed to only run in application route callbacks and Middleware should only act on the request and response objects.

This is because the app's redirect() method calls through to stop() which throws a Stop exception which is intended to be caught by the app's call() method. However, if this exception is thrown in middleware, then it isn't caught by call() and the redirect doesn't work. What's weird is that it works on some (most?) web servers but not all.

The correct way to redirect in middleware, use the Response's redirect() method instead like this:

class Authentication extends \Slim\Middleware
{
    public function call()
    {
        if (!$this->isLoggedIn()) {
            $app = \Slim\Slim::getInstance();
            return $app->response()->redirect($app->urlFor('login'));
        }

        $this->next->call();
    }

    // other methods...
}

Note that we return the result of $response->redirect() so that the next item in the chain isn't called.

Speaking at DPC & OSCON

Two conferences are coming up that I'm speaking at:

I'm speaking at DPC 2014

The Dutch PHP Conference takes place in Amsterdam and this year is between June 26th and 28. I'm giving a tutorial with Matthew Weier O'Phinney on Apigility which will provide you with a full day's teaching on creating web APIs with Apigility. I'm also giving a talk called Creating Models discussing the options available when creating the model layer of a typical MVC PHP application.

DPC is a fantastic conference full of great content and people and if you can get to Amsterdam at the end of June, it's well worth your time to attend.

I'm speaking at OSCON 2014

The following month, I'm coming to the US to speak at OSCON which runs from the 20th to 24th July in Portland. OSCON is a massive conference that covers the entire spectrum of Open Source and I'm excited to be presenting Creating Models in the PHP track. There's a lot on the schedule and I expect to learn a lot and meet lots of people from communities that I haven't interacted with much before. I've never been to Portland before, so it'll be interesting to see what the city has to offer too.

If you attend either of these conferences, please come and say hello!

Immutable entities

I've been thinking recently about using immutable objects for some of my model-layer entities. That is, an object that cannot be changed once it is created.

Immutable objects have a number of benefits including the fact that they are much easier to understand, simple to use and very easy to test. The main motivation for me is that an immutable object is very predictable as it's state doesn't change. This means that any calculated properties can be done once on creation. This is interesting as one application that I'm currently working on has a lot of calculated properties and it's a source of bugs when one property changes and all the dependent calculations aren't always done.
Continue reading

Use statements

I was having a discussion on IRC about use statements and whether they improved code readability or not.

The choices

Consider this hypothetical code:

$cache = new \User\Service\Cache();
$mapper = new \User\Mapper\User($cache)
$form = new \User\Form\Registration($mapper);
$form->process($request->getPost());

vs

use User\Service\Cache;
use User\Mapper\User;
use User\Form\Registration;

// other code

$cache = new Cache();
$db = new User($cache)
$form = new Registration($mapper);
$form->process($request->getPost());

The first snippet is completely unambiguous at the expense of verbosity. Those longer class names make it a little hard to quickly parse what it going on. The second is clearly less cluttered, but is at the expense of ambiguity. Exactly what class is User? I would have to go to the top of the file to find out. Should I use aliases? If so, how should I name them?
Continue reading

Using PHP's NumberFormatter to format currencies

I've been using number_format() for a very long time, but recently discovered that within the intl extension there's a NumberFormatter class available too. This is quite a clever class as it is Locale aware and handles formatting currency, including the correct symbol.

You can check if you have the intl extension installed using php -m | grep intl and if you don't then you can install it with apt-get install php5-intl or yum install php-intl assuming you use your distro's stock PHP. (If you compile your own, then --enable-intl is the switch you need.)

Consider this scenario where I want to display a price in Euros for both the UK and the German markets:

$amount = '12345.67';

$formatter = new NumberFormatter('en_GB',  NumberFormatter::CURRENCY);
echo 'UK: ' . $formatter->formatCurrency($amount, 'EUR') . PHP_EOL;

$formatter = new NumberFormatter('de_DE',  NumberFormatter::CURRENCY);
echo 'DE: ' . $formatter->formatCurrency($amount, 'EUR') . PHP_EOL;

The constructor takes the locale to use along with the type of formatting you want to do, CURRENCY in this case. Then, when you call formatCurrency(), the second parameter is the 3-letter alphabetic ISO 4217 code for the currency you want to display.

The output of the code above is:

UK: €12,345.68
DE: 12.345,68 €

You can see the locale at work here as in the UK we expect to see the currency symbol before the number and use comma to separate thousands, whereas in Germany, the currency symbol is (usually!) at the end of the number and the decimal point is used to separate the thousands.

The ISO 4217 currency code determines which currency symbol is returned. Obviously, for EUR, we get the € symbol. For GBP, we'd get £, etc.

Finally, if you use ZF2, this is all wrapped up into the currencyFormat view helper for you.