PHP: removing zero values from an array

If you call array_filter without a callback function, it’ll remove all array elements that evaluate to false (including zeroes).

$numbers = array(0, 1, 2, 0);
echo array_filter($numbers);

Produces:

array(1,2);

PHP: returning an array of single attributes from an array of objects

I miss Ruby’s shorthand collect method to return an array of single attributes:

animals.collect(&:name)

…so I’ve created a (less elegant) equivalent for PHP.

class ArrayExtensions
{
    /**
     * From an array of objects, create a new array containing only 
     * a single attribute of each object
     * 
     * Similar to array.collect(&:attribute) in Ruby
     */
    public static function collect_by_attribute($attribute, $array_of_objects)
    {
        if (!is_array($array_of_objects))
        {
            return array();
        }

        $output = array();

        foreach ($array_of_objects as $object)
        {
            if (is_object($object) && isset($object->$attribute))
            {
                $output[] = $object->$attribute;
            }
        } 
        
        return $output;
    }
}

Use it like this:

$colours = ArrayExtensions::collect_by_attribute('colour', $animals);

…and you’ll get a simple array containing just the attribute you’ve specified:

array('brown', 'blue', 'green')

Update

If you happen to be using PHP ActiveRecord, they have a function called collect that will accomplish the same thing.

$colours = ActiveRecord\collect($animals, 'colour');

PHP: check if a PEAR class is installed

You can’t use file_exists because it doesn’t search the include path.

fopen has a third argument that will check the include path, though:

if (@fopen('Log.php', 'r', true)) 
{   
  echo 'It exists!'; 
}

Regular expression to validate yyyy-mm-dd dates

if(!preg_match('/^(\d{4})-((0[1-9])|(1[0-2]))-(0[1-9]|[12][0-9]|3[01])$/', $date)) {
  throw new sfException('Date must be in yyyy-mm-dd format');
}

Symfony: accessing the request

The commonly used

$this->getRequestParameter('blah')

is a shortened version of

$this->getRequest()->getRequestParameter('blah')

All sorts of other goodies are available using $this->getRequest(), including for example:

$this->getRequest()->getPathInfo()

Symfony: current module name

$moduleName = sfContext::getInstance()->getModuleName();

Case insensitivity in regular expressions

Use the letter i after the ending delimiter. For example:

preg_match("/^TMG-[A-Z]-([0-9]+)/i",$itemNumber)

PHP: adding zero-padding

Use str_pad().

str_pad(42, 5, '0', STR_PAD_LEFT); // produces "00042"

PHP: sessions that work across subdomains

The solution is to use session_set_cookie_params() to allow any subdomain to access the session:

session_set_cookie_params (86400,'','.yourdomain.co.uk');
session_start();

Note the dot before the domain name. session_set_cookie_params() must be called before session_start(), and must be called on every request.

PHPMyAdmin 2.6.x bug: ISNULL

The SQL parser in PHPMyAdmin 2.6.x (the version used in Plesk 7.5) falls over when confronted with an ISNULL query, for example:

SELECT ISNULL(id) FROM user

The bug is fixed in recent versions of PMA (2.9.x works fine).