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PHP II - Aug 2022

TODO

Locate URL for PHP 5 to 7 converter

Homework

For Tue 16 Aug 2022

VM Notes

Info

  • Username: vagrant
  • Password: vagrant

Update everything!

  • Open a terminal window and run this command:
sudo apt update
sudo apt -y upgrade
  • NOTE: this task might take some time

Install phpMyAdmin

  • Download the latest version from https://www.phpmyadmin.net
  • Make note of the version number (e.g. 5.2.0)
cd
VER=5.2.0
unzip Downloads/phpMyAdmin-$VER-all-languages.zip
sudo cp -r phpMyAdmin-$VER-all-languages/* /usr/share/phpmyadmin
sudo cp /usr/share/phpmyadmin/config.sample.inc.php /usr/share/phpmyadmin/config.inc.php
  • Create the "blowfish secret"
sudo -i
export SECRET=`php -r "echo md5(date('Y-m-d-H-i-s') . rand(1000,9999));"`
echo "\$cfg['blowfish_secret']='$SECRET';" >> /usr/share/phpmyadmin/config.inc.php
exit

Set permissions

sudo chown -R www-data /usr/share/phpmyadmin

Snapshot

  • Be sure to take a snapshot of the VM before you start any of the labs!

System Problem

  • If you see this message: System program problem detected
  • Do this:
sudo rm -r /var/crash*

Resources

Code examples: https://github.com/dbierer/classic_php_examples PHP Road Map: https://wiki.php.net/rfc Where it all started:

Class Notes

Namespaces

Autoloader Examples:

Class example:

<?php
namespace My\Different\Space;

// you can identify PHP classes like this:
use ArrayObject;
class Test
{
    public function test()
    {
        return __NAMESPACE__;
    }
    public function getArrayObject(array $arr)
    {
        // or: use leading backslash:
        return new \ArrayObject($arr);
    }
}

Calling program:

<?php
include __DIR__ . '/Test.php';
use My\Different\Space\Test;

// alternatively, you can do this:
// $test = new \My\Different\Space\Test();

$test = new Test();
echo $test->test();

$arr = [1,2,3,4,5];
$obj = $test->getArrayObject($arr);
var_dump($obj);

Call methods from inside a class: use $this

<?php
class Test
{
        protected string $first = 'fred';
        protected string $last  = 'flintstone';
        public function getFirst()
        {
                return ucfirst($this->first);
        }
        public function getLast()
        {
                return ucfirst($this->last);
        }
        public function getName()
        {
                return $this->getFirst() . ' ' . $this->getLast();
        }
}
$test = new Test();
echo $test->getName();

Example using __construct()

<?php
class UserEntity {
    protected string $firstName;
    protected string $lastName;
    public function __construct($firstName, $lastName) {
        $this->firstName = $firstName ;
        $this->lastName = $lastName ;
    }
    public function getName()
    {
                return $this->firstName . ' ' . $this->lastName;
        }
}

$user[] = new UserEntity('Jack' , 'Ryan');
$user[] = new UserEntity('Monte' , 'Python');
foreach ($user as $obj)
        echo $obj->getName() . "\n";

Constructor argument promotion example:

<?php
class Test
{
        // contructor argument promotion
        // only in PHP 8.0 and above
        public function __construct(public string $first = '', public string $last = '')
        {
                // do nothing
        }
        public function getFirst()
        {
                return ucfirst($this->first);
        }
        public function getLast()
        {
                return ucfirst($this->last);
        }
        public function getName()
        {
                return $this->getFirst() . ' ' . $this->getLast() . "\n";
        }
}
$test1 = new Test('Fred', 'Flintstone');
echo $test1->getName();

$test2 = new Test('Wilma', 'Flintstone');
echo $test2->getName();

var_dump($test1, $test2);

Practical anonymous class example:

Magic Methods

Example of __destruct()

<?php
class UserEntity
{
        public $status = ['A','B','C'];
    public function __construct(
        protected string $firstName,
        protected string $lastName,
        protected float $balance,
        protected int $id
    ) {}
        public function getFullName()
        {
                return $this->firstName . ' ' . $this->lastName;
        }
}
$user = new UserEntity('Fred', 'Flintstone', 999.99, 101);
$text = serialize($user);
//$text = json_encode($user);
echo $text . "\n";
$obj = unserialize($text);
//$obj = json_decode($text);
echo $obj->getFullName() . "\n";
var_dump($obj);

Example of __sleep() and __wakeup()

<?php
class UserEntity {
        public $hash = '';
    public function __construct(
        protected string $firstName,
        protected string $lastName)
    {
                $this->hash = bin2hex(random_bytes(8));
    }
    public function __sleep()
    {
                return ['firstName','lastName'];
        }
        public function __wakeup()
        {
                $this->hash = bin2hex(random_bytes(8));
        }
        public function getFullName()
        {
                return $this->firstName . ' ' . $this->lastName;
        }
    public function getNativeString(): string {
        return serialize($this);
    }
}
$userEntity = new UserEntity('Mark', 'Watney');
var_dump($userEntity);
echo PHP_EOL;

$native = $userEntity->getNativeString();
$obj  = unserialize($native);
echo $native;
echo PHP_EOL;
var_dump($obj);

Example of __serialize() and __unserialize()

<?php
class UserEntity {
        public $hash = '';
    public function __construct(
        protected string $firstName,
        protected string $lastName)
    {
                $this->hash = bin2hex(random_bytes(8));
    }
    public function __serialize()
    {
                return [
                        'firstName' => $this->firstName,
                        'lastName' => $this->lastName,
                        'sleep_date' => date('Y-m-d H:i:s')];
        }
        public function __unserialize($array)
        {
                // $array contains values restored from the serialization
                $this->hash = bin2hex(random_bytes(8));
                $this->firstName = $array['firstName'];
                $this->lastName = $array['lastName'];
        }
        public function getFullName()
        {
                return $this->firstName . ' ' . $this->lastName;
        }
    public function getNativeString(): string {
        return serialize($this);
    }
}
$userEntity = new UserEntity('Mark', 'Watney');
var_dump($userEntity);
echo PHP_EOL;

$native = $userEntity->getNativeString();
$obj  = unserialize($native);
echo $native;
echo PHP_EOL;
var_dump($obj);

Example of when getters and setters are useful:

class Test
{
    protected $date;
    const DEFAULT_FMT = 'Y-m-d H:i:s';
    // use getters and setters if there's a need for further processing
    public function setDate(string $str) : void
    {
                $this->date = new DateTime($str);
        }
        public function getDate(string $fmt = self::DEFAULT_FMT) : string
        {
                return $this->date->format($fmt);
        }
}

Example of controlled unlimited properties

<?php
class Test
{
        public const FIELDS = ['fname','lname','balance'];
        public $vars = [];
    // Returns an inaccessible property
    public function __set($key, $value) {
        if (in_array($key, self::FIELDS)) {
                        $this->vars[$key] = $value;
                }
    }
    public function __get($key) {
        return $this->vars[$key] ?? '';
    }
}

$test = new Test();
$test->fname = 'Fred';
$test->lname = 'Flintstone';
$test->balance = 999.99;
$test->doesNotExist = 'TEST';
echo $test->fname . ' ' . $test->lname
         . ' has a balance of ' . $test->balance
         . ' and ' . $test->doesNotExist;

Allows direct access to protected properties

class UserEntity {
    public function __construct(
        protected string $firstName,
        protected string $lastName
    ) {}

    // Returns an inaccessible property
    public function __get($value) {
        return $this->$value ?? NULL;
    }
}

$userEntity = new UserEntity('Mark', 'Watney');
echo $userEntity->firstName;
// outputs: "Mark" even though property is protected

Other examples of magic methods:

Example of Abstract class with abstract method:

<?php
interface Foo {
    public function test(array $input);
}

class Bar implements Foo {
    // type omitted for $input
    public function test(iterable $input) {
                $text = '';
                foreach($input as $item) $text .= ' ' . $item;
        return 'You requested ' . trim($text);
    }
}

$bar = new Bar();
echo $bar->test(['A','B','C']);
echo $bar->test(new ArrayIterator(['A','B','C']));
  • Using static to get an instance of the lowest level in inheritance tree
<?php
class Foo
{
        public function whatever()
        {
                return 'Whatever';
        }
        public function getInstance() : static
        {
                // this returns an error:
                // return new self();
                return new static();
        }
}
class Bar extends Foo {}

$foo = new Foo();
$bar = new Bar();
var_dump($foo->getInstance());  // Foo
var_dump($bar->getInstance());  // Bar

Exception / Error example:

<?php
try {
        $pdo = new PDO('sqlite://xyz');
} catch (PDOException $a) {
        // catches PDOException
        echo __LINE__ . ':' . get_class($a) . ':' . $a . "\n";
} catch (Exception $a) {
        echo __LINE__ . ':' . get_class($a) . ':' . $a . "\n";
} catch (Error $a) {
        echo __LINE__ . ':' . get_class($a) . ':' . $a . "\n";
}

try {
        $pdo = new PDO();
} catch (PDOException $a) {
        echo __LINE__ . ':' . get_class($a) . ':' . $a . "\n";
} catch (Exception $a) {
        echo __LINE__ . ':' . get_class($a) . ':' . $a . "\n";
} catch (Error $a) {
        // catches Error
        echo __LINE__ . ':' . get_class($a) . ':' . $a . "\n";
}
// actual output:
/*
6:PDOException:PDOException: SQLSTATE[HY000] [14] unable to open database file in C:\Users\ACER\Repos\classic_php_examples\oop\test.php:3
Stack trace:
#0 C:\Users\ACER\Repos\classic_php_examples\oop\test.php(3): PDO->__construct()
#1 {main}
21:ArgumentCountError:ArgumentCountError: PDO::__construct() expects at least 1 argument, 0 given in C:\Users\ACER\Repos\classic_php_examples\oop\test.php:14
Stack trace:
#0 C:\Users\ACER\Repos\classic_php_examples\oop\test.php(14): PDO->__construct()
#1 {main}
*/

Using static functionality to get a singleton instance

PDO

Adding options as 4th argument:

try {
    // Get the connection instance
    $opts = [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION];
    $pdo = new PDO('mysql:host=localhost;dbname=phpcourse', 'vagrant', 'vagrant', $opts);
    // Statements ...
} catch (PDOException $e ){
    // Handle exception...
}

To find the exact DSN for a given database in PDO, look at the Driver class documentation

try {
    // Execute a one-off SQL statement and get a statement object
    $stmt = $pdo->query('SELECT * FROM orders');

    // Returns an associative array indexed by column name
    while ($row = $stmt->fetch(PDO::FETCH_ASSOC) {
                // do something with the resulting row
        }

} catch (PDOException $e){
    //Handle error
}

Alternative way to execute without using bindParam()

$data = [
        'eventTitle' => 'Wagner, Bryant',
        'eventURL' => 'http://bryant.prestosports.com/sports/bsb/2021-22/schedule#6irpaohben8y4ati',
        'eventDescription' => 'Baseball on May 21, 2022 at 3:00 PM: Wagner, Bryant, Conaty Park',
        'eventCategory' => 'Baseball',
        'eventDateString' => 'Sat, 21 May 2022 19:00:00 GMT',
        'eventGUID' => 'http://bryant.prestosports.com/sports/bsb/2021-22/schedule#6irpaohben8y4at',
        'eventOpponent' => 'Wagner',
];
$stmt->execute($data);

Example of PDO::FETCH_CLASS mode:

Output Buffering

To start output buffering automatically, in the php.ini file:

// sets buffer size to 4K + activates it
output_buffering=4096

Email

Headers can include any valid headers as per RFC 2822

Regex

Alternatives to finding chars at beginning or end of a string:

<?php
$str = '/home/doug/whatever/';

// Any PHP above 4
echo ($str[0] ==='/') ? 'Y' : 'N';
echo ($str[-1] ==='/') ? 'Y' : 'N';

// PHP 8
echo (str_starts_with($str,'/')) ? 'Y' : 'N';
echo (str_ends_with($str,'/')) ? 'Y' : 'N';

Examples using sub-patterns

<?php
$str = '<p>One</p><p>Two</p><p>Three</p>';
$pat = '/<p>(.*?)<\/p>/';
preg_match_all($pat, $str, $match);
var_dump($match);


$str = 'Click here to go to <a target="_blank" href="http://zend.com/">Zend</a>!';
$pat = '/<a.*?href=("|\')(.*?)("|\').*?>/';
preg_match_all($pat, $str, $match);
var_dump($match);

Composer

Example of advanced usage including scripts

Web Services

Example of SOAP Client

<?php
$data = array ('foo' => 'bar', 'bar' => 'baz');
$data = http_build_query($data);
$context_options = array (
        'http' => array (
            'method' => 'POST',
            'header'=> "Content-type: application/x-www-form-urlencoded\r\n"
                . "Content-Length: " . strlen($data) . "\r\n",
            'content' => $data
            )
        );

$context = stream_context_create($context_options)
$fp = fopen('https://url', 'r', false, $context);

Study by Oracle that compares SOAP and REST

Output Control

Example using output buffering to create inner content

<?php
ob_start ();

$values = ['TH'=>'Thailand','GB'=>'Great Britain','FR'=>'France'];
foreach ($values as $key => $val)
        echo '<tr><th>' . $key . '</th><td>' . $val . '</td></tr>';

$contents = ob_get_clean();

echo '<h1>My Cool Webpage</h1>';
echo '<table>';
echo $contents;
echo '</table>';

Regex

Misc examples

<?php
$data = [
        '/^[A-Z].*/'     => ['The quick brown fox', '12345'],
        '/.*(jpg|png)$/' => ['image.png', 'info.php'],
        '/\bERROR\b/'    => ['ERROR 309: undefined error','This contains ERROR_REPORTING'],
        '/^[A-Za-z ]*$/'  => ['The quick brown fox', '9977 quick brown foxes'],
        '/^[^A-Za-z]*$/' => ['997799989887777','The quick brown fox'],
        '!^http(s)?://\w*!i' => ['https://zend.com','http://sandbox','ftp://whatever.com'],
];

foreach ($data as $pattern => $value) {
        foreach ($value as $item) {
                echo "Testing $item\n";
                echo (preg_match($pattern, $item)) ? 'MATCH' : 'NO MATCH';
                echo PHP_EOL;
        }
}

PHP 5 to PHP 7 code converter using preg_replace_callback_array()

Q & A