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PHP Foundations -- Oct 2023

Last: http://localhost:8881/#/5/17

TODO

Homework

Homework for Fri 17 Nov 2023

VM Notes

Expanded VM Instructions

Info

  • Username: vagrant
  • Password: vagrant

Do Not Accept the Update or Upgrade Prompts

  • Once you login it's important to wait a few seconds for the system to come fully up.
  • At this point you'll see two prompts: one to update, one to upgrade. Be sure to decline both of these options! Confirm that no unattended upgrades are in progress:
ps -ax |grep unattended

If you see any listed (except for the last one which is the grep command):

  • Make a note of the "process ID" (PID)
  • Kill the process as follows:
sudo kill [PID]

Now you can do the full update/upgrade

  • This doesn't upgrade the OS, just the packages
  • Open a command terminal and run these commands.
sudo dpkg --configure -a
sudo apt -y update && sudo apt -f -y install && sudo apt -y full-upgrade

It will take several hours to complete so it's best to let it run overnight.

Accept New Configuration

  • At some point you will be asked if you wish to retain the original php.ini configuration or accept the new. Go ahead and accept the new configuration.

Update Apache PHP Module

  • So far PHP from the command line (PHP-CLI) has been updated. You'll still need to update the PHP Apache module using these commands. Please note that "8.0" is the old version, and "8.2" is the new version. You may have to change these two values as more recent versions become available.
sudo apt-add-repository ppa:ondrej/apache2
sudo apt install libapache2-mod-php8.2
sudo a2dismod php8.0
sudo systemctl restart apache2
sudo a2enmod php8.2
sudo systemctl restart apache2

Installing Adminer database administration tool:

  • From the VM using its browser, download the desired version (e.g. adminer-4.8.1-mysql-en.php)
  • Move from the Downloads folder to /var/www/html
# example:
sudo cp adminer-4.8.1-mysql-en.php /var/www/html/adminer.php
  • Access from your browser: http://localhost/adminer.php

Class Notes

php.ini settings:

Example of type juggling with comparison operators:

<?php
ini_set('display_errors', 1);
error_reporting(E_ALL);

$a = '111';
$b = 111;
echo ($a == $b) ? 'Equal' : 'Not Equal';
// Equal

$a = ' 111 '; // recommended: use trim($a)
$b = 111;
echo ($a == $b) ? 'Equal' : 'Not Equal';
// Equal

$a = ' 111 x';
$b = 111;
echo ($a == $b) ? 'Equal' : 'Not Equal';
// Not Equal

$a = 'x111x';
$b = 111;
echo ($a == $b) ? 'Equal' : 'Not Equal';
// Not Equal

$a = 'ABC';
$b = 111;
echo ($a == $b) ? 'Equal' : 'Not Equal';
// Not Equal

// this causes a Fatal Error because PHP might lose precision
echo $a + $b;
// Fatal error:  Uncaught TypeError: Unsupported operand types: string + int in /home/vagrant/Zend/workspaces/DefaultWorkspace/sandbox/public/test.php:31

For comparison logicals, you can use words instead of symbols:

<?php
$foo = 10;
$bar = 5;
echo ($foo == 10 && $bar == 5); // 1

$foo = 5;
$bar = 10;
echo ($foo != $bar || $foo > $bar); // 1
echo ($foo != $bar ^ $foo > $bar); // 1

$foo = 10;
$bar = 5;
echo ($foo == 10 and $bar == 5); // 1

$foo = 5;
$bar = 10;
echo ($foo != $bar or $foo > $bar); // 1
echo ($foo != $bar xor $foo > $bar); // 1

If you want to publish PHP code to the http://sandbox/xxx.php

  • Just create the code in this directory in the VM:
/home/vagrant/Zend/workspaces/DefaultWorkspace/sandbox/public

Docblocks

Useful string functions:

  • substr()
  • str_replace()
  • strpos()

How PHP actually works:

Pre-assigning default values that match the data type:

<?php
$a = '';	// string
$b = 0;		// int
$c = 0.0;	// float
$d = TRUE;	// bool

var_dump($a, $b, $c, $d);

Pre-defined constants

Mixing HTML and PHP:

  • If you do this you need the closing tags!
<?php $name = 'Steven'; ?>
<h1><?= $name; ?></h1>

Example using the modulus operator to determine remaining minutes:

<?php
$min = 795;
$hours = (int) ($min / 60);
$remain = $min % 60;
echo '$min is $hours hours and $remain minutes\n';

Determining the datatype at runtime

<?php
// use is_* functions to check the data type
$astronaut = ['Mark', 'Watney', 'Botanist'];
if (is_array($astronaut)) {
	print_r($astronaut);
} elseif (is_string($astronaut)) {
	echo $astronaut;
} else {
	echo 'Unknown';
}
// use gettype() to reveal the data type
echo gettype($astronaut);

Using the spread operator to flatten two sub-arrays

<?php
$business = ['Mon','Tue','Wed','Thu','Fri'];
$weekend  = ['Sat','Sun'];
$days     = [$business, $weekend];
var_dump($days);
// actual output:
/*
 * array(2) {
  [0]=>
  array(5) {
    [0]=>
    string(3) 'Mon'
    [1]=>
    string(3) 'Tue'
    [2]=>
    string(3) 'Wed'
    [3]=>
    string(3) 'Thu'
    [4]=>
    string(3) 'Fri'
  }
  [1]=>
  array(2) {
    [0]=>
    string(3) 'Sat'
    [1]=>
    string(3) 'Sun'
  }
}
*/

// the spread op (variadics) flattens the 2 sub-arrays into a single linear array
$days     = [...$business, ...$weekend];
var_dump($days);
// actual output:
/*
 * array(7) {
  [0]=>
  string(3) 'Mon'
  [1]=>
  string(3) 'Tue'
  [2]=>
  string(3) 'Wed'
  [3]=>
  string(3) 'Thu'
  [4]=>
  string(3) 'Fri'
  [5]=>
  string(3) 'Sat'
  [6]=>
  string(3) 'Sun'
*/

Packing arguments

<?php
// example using ... to pack an array

function test(...$a)
{
	return array_sum($a);
}

echo test(1,2,3,4,5);
echo PHP_EOL;
echo test(6,7,8,8,10,11,12,13,14,15);
// output: 15
//         104

Difference between define() and const regarding constants:

<?php
define('PATH', __DIR__);

class Test
{
	const PATH = '/var/www/html';
	public function getInternalPath()
	{
		return self::PATH;
	}
	public function getExternalPath()
	{
		return PATH;
	}
}

echo PATH;			// current dir
echo PHP_EOL;
echo Test::PATH;	// /var/www/html
echo PHP_EOL;

$test = new Test();
echo $test->getExternalPath();	// current dir
echo PHP_EOL;
echo $test->getInternalPath();	// /var/www/html
echo PHP_EOL;

Adding elements to a multi-dimensional array

<?php
$mission = [
    'STS395' => [
        ['firstName' => 'Mark', 'lastName' => 'Watney', 'specialty' => 'Botanist'],
        ['firstName' => 'Melissa', 'lastName' => 'Lewis', 'specialty' => 'Commander'],
        ['firstName' => 'Beth', 'lastName' => 'Johanssen', 'specialty' => 'Computer Specialist 2'],s
        // here's how to add as part of the initial assignment
        ['firstName' => 'Fernanda', 'lastName' => 'Fernandes', 'specialty' => 'Computer Specialist 1'],
    ]
];

// here's how to add *after* the initial assignment
$mission['STS395'][] = ['firstName' => 'William', 'lastName' => 'Hodge', 'specialty' => 'Drupal Specialist'];

// here's how to make specific direct assignments
$mission['STS395'][5]['firstName'] = 'William';
$mission['STS395'][5]['lastName']  = 'Hodge';
$mission['STS395'][5]['specialty'] = 'Drupal Specialist';

// overwrite existing values
$mission['STS395'][2]['specialty'] = 'WordPress Specialist';

print_r($mission);

Another multi-dim array example:

<?php
$mission = [
    'STS395' => [
        ['firstName' => 'Mark', 'lastName' => 'Watney', 'specialty' => 'Botanist'],
        ['firstName' => 'Melissa', 'lastName' => 'Lewis', 'specialty' => 'Commander'],
        ['firstName' => 'Beth', 'lastName' => 'Johanssen', 'specialty' => 'Computer Specialist']
		// adds right here
    ]
];

$mission['STS395'][] = ['firstName' => 'Fred', 'lastName' => 'Flintstone', 'specialty' => 'Caveman'];
$mission['STS396'][] = ['firstName' => 'Barney', 'lastName' => 'Rubble', 'specialty' => 'Caveman Neighbor'];

$mission['STS396'][0]['firstName'] = 'Betty';

print_r($mission);

// actual output:
/*
Array
(
    [STS395] => Array
        (
            [0] => Array
                (
                    [firstName] => Mark
                    [lastName] => Watney
                    [specialty] => Botanist
                )

            [1] => Array
                (
                    [firstName] => Melissa
                    [lastName] => Lewis
                    [specialty] => Commander
                )

            [2] => Array
                (
                    [firstName] => Beth
                    [lastName] => Johanssen
                    [specialty] => Computer Specialist
                )

            [3] => Array
                (
                    [firstName] => Fred
                    [lastName] => Flintstone
                    [specialty] => Caveman
                )

        )

    [STS396] => Array
        (
            [0] => Array
                (
                    [firstName] => Betty
                    [lastName] => Rubble
                    [specialty] => Caveman Neighbor
                )

        )

)
*/

Example using the ternary operator to establish a default value when accessing URL params

<?php
$name = (!empty($_GET['name'])) ? strip_tags($_GET['name']) : 'Default';
echo '<h1>' . $name . '</h1>';

Another example using the ternary operator + input and output sanitization:

<?php
// sanitize inputs using "strip_tags()"
$first = (isset($_GET['first'])) ? strip_tags($_GET['first']) : 'Default';
$last  = (isset($_GET['last'])) ? strip_tags($_GET['last']) : 'Default';

// output escaping:
echo htmlspecialchars($first . ':' . $last);

This is the same thing as above, but uses the ?? instead:

<?php
// sanitize inputs using "strip_tags()"
$first = strip_tags($_GET['first'] ?? 'Default');
$last  = strip_tags($_GET['last'] ?? 'Default');

// output escaping:
echo htmlspecialchars($first . ':' . $last);

You can use the '??' in place of a series of if/elseif

<?php
$status = (int) ($_REQUEST['status'] ?? $_SESSION['status'] ?? $_COOKIE['status'] ?? 1);
// same thing but using if/elseif:
if (!empty($_REQUEST['status'])) {
	$status = $_REQUEST['status'];
} elseif (!empty($_SESSION['status'])) {
	$status = $_SESSION['status'];
} elseif (!empty($_COOKIE['status'])) {
	$status = $_COOKIE['status'];
} else {
	$status = 1;
}

You can also add a 'default' option to match expressions:

<?php
// NOTE: match does a *strict* comparison (checks data type first)
$result = match ('1') {
    0 => 'Foo',
    1 => 'Bar',
    2 => 'Baz',
    default => 'None of the above'
};
echo $result; // None of the above

Iterating through nested foreach() loops

  • NESTING_LEVEL -1 == the number of foreach() loops needed to get to the lowest level of information
<?php
// Build the crew
$missions = [
	'STS395' => [
		['firstName' => 'Mark', 'lastName' => 'Watney', 'specialty' => 'Botanist'],
		['firstName' => 'Melissa', 'lastName' => 'Lewis', 'specialty' => 'Commander'],
		['firstName' => 'Beth', 'lastName' => 'Johanssen', 'specialty' => 'Computer Specialist'],
	]
];

foreach($missions as $mission => $astronauts) {
	echo $mission . PHP_EOL;
    foreach ($astronauts as $row) {
		echo '{$row['specialty']} {$row['lastName']} on board' . PHP_EOL;
    }
}

Using for() to count backwards

<?php
$max = 100;
$min = 50;
for ( $i = $max; $i >= $min; $i--) {
    echo 'Count to $i' . '<br>' . PHP_EOL;
}

Break out sub-arrays in a foreach() loop using list() (or alternatively [])

<?php
$arr = [
	['Fred','Flintstone','Caveman'],
	['Wilma','Flintstone','Cavewoman'],
	['George','Slate','Boss'],
];

foreach ($arr as [$first,$last,$role]) {
	echo '$first $last is a $role\n';
}

// NOTE: you could also write the foreach() loop as follows:
// foreach ($arr as list($first,$last,$role)) {

// actual output:
/*
Fred Flintstone is a Caveman
Wilma Flintstone is a Cavewoman
George Slate is a Boss
*/

Example of "Fail Early"

<?php
// trivial example of fail early
$fn = __DIR__ . '/people.txt';

function countLines(string $fn)
{
	// check to see if the file exists
	// if not, no point to continue
	if (!file_exists($fn)) return 0;
	return count(file($fn));
}

echo 'The file ' . basename($fn) . ' has ' . countLines($fn) . ' lines' . PHP_EOL;

Example using list() to break out arrays into their components:

<?php
$data = [
	['Fred','Flintstone','Caveman'],
	['Wilma','Flintstone','Cavewoman'],
	['Barney','Rubble','Neighbor'],
	['Betty','Rubble','Neighbor Wife'],
];

foreach ($data as list($first,$last,$role)) {
	echo "$first $last has the role of $role\n";
}

// actual output:
/*
Fred Flintstone has the role of Caveman
Wilma Flintstone has the role of Cavewoman
Barney Rubble has the role of Neighbor
Betty Rubble has the role of Neighbor Wife
*/

When working with International customers, the declare(encoding=xxx) is limited to that file

  • For more flexibility consider using mb_convert_encoding()
  • For that to work the mbstring extension must be enabled
    • For example, on Ubuntu, you can do this: sudo apt install php8.2-mstring
    • Alternatively, activate manually in the php.ini file

You should provide a data type hint for functions with components that are sensitive to the wrong data type

  • Protects the function from abuse
  • Makes the real source of the error quite clear
function searchForError(array $messages) : int
{
	$found = 0;
	$search = 'ERROR';
	foreach ($messages as $item) {
		if (str_contains($item, $search)) {
			$found++;
			break;
		}
	}
	return $found;
}
$messages = [
	'Operation succeeded',
	'ERROR 402',
	'Parse ERROR',
	'Everything OK',
];

echo (searchForError('WHATEVER'))
	? 'ERROR found'
	: 'All OK';

If you allow for NULL and pass it as a value, it overrides the default assignment:

<?php
// allows "string" as a type hint
function welcome(string|null $arg = 'JavaScript') :string {
    return "Welcome to the wonderful world of $arg coding\n";
}

$type = 'Python';

echo welcome();
echo welcome('PHP');
echo welcome($type);
echo welcome(NULL);

// actual output:
/*
Welcome to the wonderful world of JavaScript coding
Welcome to the wonderful world of PHP coding
Welcome to the wonderful world of Python coding
Welcome to the wonderful world of  coding
*/

Producing an HTML list from an array using the "splat" operator to allow unlimited args

<?php
function arrayToHtml(...$args)
{
    $output = '<ul>' . PHP_EOL;
    // $args = func_get_args();
    if(count($args)){
        foreach($args as $arg){
            $output .= '<li>' . $arg . '</li>' . PHP_EOL;
        }
    }
    $output .= '</ul>' . PHP_EOL;
    return $output;
}

echo arrayToHtml('Mark', 'Watney', 'Botanist', 'Doctor of Philosophy');

// output:
/*
<ul>
<li>Mark</li>
<li>Watney</li>
<li>Botanist</li>
<li>Doctor of Philosophy</li>
</ul>
*/

Use declare(strict_types=1) to enforce all type hints for that file

<?php
// if the following line is omitted, the type-hint acts like a filter (type-cast)
declare(strict_types=1);
// Example of function using 'type hinting'
function add(int $a, int $b) : int
{
	return $a + $b;
}

echo 'The sum of 2 and 2 is ' . add(2, 2) . '\n';
echo 'The sum of 33.33 and 22.22 is ' . add(33.33, 22.22) . '\n';

Nullable type: ?string === string|null

<?php
// union types were introduced in PHP 8

function get_full_name(string $first, string $last, string|null $middle = NULL)
{
	return ($middle) ? '$first $middle $last\n' : '$first $last\n';
}

echo get_full_name('Fred', 'Flintstone', 'John');
echo get_full_name('Barney', 'Rubble');

// prior to PHP 8, a hybrid type:
// ?string === string|null

function get_full_name2(string $first, string $last, ?string $middle = NULL)
{
	return ($middle) ? '$first $middle $last\n' : '$first $last\n';
}

echo get_full_name2('Fred', 'Flintstone', 'John');
echo get_full_name2('Barney', 'Rubble');

Union types can go overboard:

<?php
// a bit ridiculous:
function dump(int|float|string|bool|array|object $whatever)
{
	var_dump($whatever);
}

dump(new ArrayObject());
dump([1,2,3,4,5]);

// this makes more sense:
function dump2(mixed $whatever)
{
	var_dump($whatever);
}

dump(new ArrayObject());

// another example of ridiculous:
// dump(true|false|bool $yesNo) {}

Array navigation functions example with while() loop

<?php
$invoiceItems = [
  ['invoiceNumber' => 123, 'invoiceAmount' => 100],
  ['invoiceNumber' => 124, 'invoiceAmount' => 50],
  ['invoiceNumber' => 125, 'invoiceAmount' => 150],
  ['invoiceNumber' => 126, 'invoiceAmount' => 55],
];

$tax = 0.10;

while ($items = current($invoiceItems)) {
    $amountWithTax =  $items['invoiceAmount'] + ($items['invoiceAmount'] * $tax);
    echo 'invoice #' . $items['invoiceNumber'] . ' with invoice amount ' . $items['invoiceAmount'] . ' has the final amount of ' .  $amountWithTax . ' after adding the tax';
    echo '\n';
    next($invoiceItems);
    // might need to add a check to make sure you're not at the end of the array
    // maybe keep a count using "++" and use the count() function to see how many elements are in the array
}

Using assignment by reference to alias an array element:

<?php
$config = [
    'router' => [
        'routes' => [
            'market' => [
                'type' => 'literal',
                'options' => [
                    'route' => '/market',
                    'defaults' => [
                        'controller' => 'IndexController',
                        'action'     => 'index',
                    ],
                ],
            ],
        ],
    ],
];
$action = &$config['router']['routes']['market']['options']['defaults']['action'];

$action = 'TEST';
var_dump($config);

// actual output:
/*
 * array(1) {
  ["router"]=>
  array(1) {
    ["routes"]=>
    array(1) {
      ["market"]=>
      array(2) {
        ["type"]=>
        string(7) "literal"
        ["options"]=>
        array(2) {
          ["route"]=>
          string(7) "/market"
          ["defaults"]=>
          array(2) {
            ["controller"]=>
            string(15) "IndexController"
            ["action"]=>
            &string(4) "TEST"
          }
        }
      }
    }
  }
}
*/

Using named parameters

<?php
// PHP 7 and below:
setcookie('Test', 1, 0, '', '', false, TRUE);
// PHP 8 allows you to use "named parameters"
setcookie('Test', 1, httponly:TRUE);

Using reference to alias an array element:

<?php
$config = [
    'router' => [
        'routes' => [
            'market' => [
                'type' => 'literal',
                'options' => [
                    'route' => '/market',
                    'defaults' => [
                        'controller' => 'IndexController',
                        'action'     => 'index',
                    ],
                ],
            ],
        ],
    ],
];
// now $action is an alias for this array element
$action = &$config['router']['routes']['market']['options']['defaults']['action'];
echo $action . PHP_EOL;
$action = 'test';
print_r($config);

Functions should have 1 entrance and 1 exit (as per the rules of Structured Programming)

<?php
function formatCurrency(float $value, string $arg='$') {
    switch (strtolower($arg)) {
        case 'euro' :
        case '€' :
            $result = number_format($value, 2, ',', ' ') . '€'; break;
        case 'pound' :
        case '£' :
            $result = '£' . number_format($value, 2, '.', ','); break;
        case 'dollar' :
        case '$' :
            $result = '$' . number_format($value, 2, '.', ','); break;
        default :
			$result = '';
    }
    return $result;
}
echo formatCurrency(9999, 'euro') ?? 'Unknown'; // 9 999,00€
echo PHP_EOL;
echo formatCurrency(9999, '$') ?? 'Unknown';    // $9,999.00
echo PHP_EOL;

Example using substr()

<?php
$url = 'http://training.zend.com/';
$scheme = substr($url, 0, 5);
if ($scheme === 'https') {
	echo 'Secure URL';
	$path = substr($url, 7);
} else {
	echo 'Insecure URL';
	$path = substr($url, 6);
}
echo PHP_EOL;
echo 'This is the path: ' . $path . PHP_EOL;

// output:
/*
Insecure URL
This is the path: /training.zend.com/
*/

Example using negative offset with substr()

<?php
$fn = __FILE__;
$ext = substr($fn, -3);
echo $fn . ' is a ' . $ext . ' file';
echo PHP_EOL;

$breakdown = explode('/', $fn);
var_dump($breakdown);
// actual output:
/*
 * /home/vagrant/Zend/workspaces/DefaultWorkspace/sandbox/public/test.php is a php file
array(9) {
  [0]=>
  string(0) ""
  [1]=>
  string(4) "home"
  [2]=>
  string(7) "vagrant"
  [3]=>
  string(4) "Zend"
  [4]=>
  string(10) "workspaces"
  [5]=>
  string(16) "DefaultWorkspace"
  [6]=>
  string(7) "sandbox"
  [7]=>
  string(6) "public"
  [8]=>
  string(8) "test.php"
}
*/

Example using stripos() and substr()

<?php
$str = file_get_contents('https://www.zend.com/');
$pos = stripos($str, 'Migrations');
if ($pos !== FALSE) {
	$start = $pos - 20;
	$end   = $pos + 12;
	echo substr($str, $start, 40);
}

// actual output:
// ration" data-title="Migrations" data-dru

Sorting examples

<?php
$arr = ['A' => 111, 'C' => 333, 'E' => 555, 'B' => 222, 'D' => 444];
var_dump($arr);
ksort($arr);
var_dump($arr);

// NOTE: using sort() is fast, but you lose the keys
$arr = ['A' => 111, 'C' => 333, 'E' => 555, 'B' => 222, 'D' => 444];
sort($arr);
var_dump($arr);

// NOTE: asort() is very very slightly slower, but keys are retained
$arr = ['A' => 111, 'C' => 333, 'E' => 555, 'B' => 222, 'D' => 444];
asort($arr);
var_dump($arr);

Similar to above with output:

<?php
$arr = ['A' => 111, 'C' => 222, 'E' => 666, 'B' => 555, 'D' => 444, 'F' => 333];

$test = $arr;
sort($test);
var_dump($test);

$test = $arr;
asort($test);
var_dump($test);

$test = $arr;
ksort($test);
var_dump($test);

$test = $arr;
arsort($test);
var_dump($test);

// actual output:
/*
 * array(6) {
  [0]=>
  int(111)
  [1]=>
  int(222)
  [2]=>
  int(333)
  [3]=>
  int(444)
  [4]=>
  int(555)
  [5]=>
  int(666)
}
array(6) {
  ["A"]=>
  int(111)
  ["C"]=>
  int(222)
  ["F"]=>
  int(333)
  ["D"]=>
  int(444)
  ["B"]=>
  int(555)
  ["E"]=>
  int(666)
}
array(6) {
  ["A"]=>
  int(111)
  ["B"]=>
  int(555)
  ["C"]=>
  int(222)
  ["D"]=>
  int(444)
  ["E"]=>
  int(666)
  ["F"]=>
  int(333)
}
array(6) {
  ["E"]=>
  int(666)
  ["B"]=>
  int(555)
  ["D"]=>
  int(444)
  ["F"]=>
  int(333)
  ["C"]=>
  int(222)
  ["A"]=>
  int(111)
}
*/

Reading a CSV file and echoing the results:

<?php
// Open and test for success
if (!$fh = fopen(__DIR__ . '/bitcoin.csv', 'r')) exit('Unable to open file');

$data = [];
while (!feof($fh)) {
    $data[] = fgetcsv($fh);
}

// Iterate the retrieved contents and output
foreach ($data as $row) {
	if (empty($row) || !is_array($row)) continue;
    echo implode("\t", $row);
    echo '<br>' . PHP_EOL;
}

// Close the resource when finished
fclose($fh);

Example using file_put_contents() and file_get_contents()

<?php
$file = 'target.txt';
$contents = 'This is a text file' . PHP_EOL;
// NOTE: file_put_contents doesn't add a linefeed
$bytes = file_put_contents( $file, $contents, FILE_APPEND);
echo "$bytes bytes written to the file: $file" . PHP_EOL;
echo file_get_contents($file);
echo PHP_EOL;

Redirect to another web page:

<?php
// this is how you redirect to another web page:
header('Location: https://training.zend.com/');
exit;

Example of HTML form + security measures

<?php
$item = '';
$priority = 0;
if(!empty($_POST)) {
    $item = $_POST['item'] ?? '';
    $priority = $_POST['priority'] ?? '';
    if(!empty($item) && !empty($priority)) {
        $item = filter_var(strip_tags($item), FILTER_SANITIZE_STRING);
        $priority = (int) $priority;
        echo 'Data is validated and sanitized, handle it ...';
    } else {
        echo 'Invalid input';
        exit;
    }
} else {
    // no form data has been posted
    echo 'No form data has been posted';
}
?>
<form action="test.php" method="post">
    <fieldset>
        <legend>Add Checklist Item</legend>
        <label for="item">Enter the checklist item</label>
        <input type="text" name="item" id="item" value="<?= htmlspecialchars($item); ?>">
        <label for="priority">Enter the priority</label>
        <input type="text" name="priority" id="priority" value="<?= htmlspecialchars($priority); ?>" >
        <input type="submit" value="Submit">
    </fieldset>
</form>

Example of a callback tree that produces output in different formats

  • Uses anonymous functions
<?php
$arr = ['A' => 111,'B' => 222,'C' => 333];

$callbacks = [
	// arrow function works well here
	'json' => fn(array $data) => json_encode($data, JSON_PRETTY_PRINT),
	// needs multiple lines of code, so we use an anonymous function
	'html' => function (array $data) {
		$out = '<table>';
		foreach ($data as $key => $value)
			$out .= '<tr><th>' . $key . '</th><td>' . $value . '</td></tr>';
		$out .= '</table>';
		return $out; }
];

echo $callbacks['json']($arr);
echo "\n";
echo $callbacks['html']($arr);
echo "\n";

Anonymous functions examples:

  • This example "stores" an SQL query for later use:
<?php
function get_select(string $table, string $where, PDO $pdo)
{
	$sql = 'SELECT * FROM ' . $table . ' WHERE ' . $where;
	return function () use ($sql) {
		$stmt = $pdo->query($sql);
		$result = [];
		while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
			$result[] = $row;
		}
		return $result;
	};
}
$select = get_select('orders', 'id = 1', $pdo);

// do something
// ...
// do something

foreach ($select() as $row) {
	// display the row
	// maybe using printf()
}

Typical production settings:

<?php
// start session and define key global constants
define('BASE_DIR', __DIR__);
define('HTML_DIR', BASE_DIR . '/templates/site');
define('SRC_DIR', BASE_DIR . '/src');
// set up error handling
error_reporting(E_ALL);
ini_set('display_errors', 0);   // change this to "1" during website development
ini_set('error_log', BASE_DIR . '/logs/error.log');
// uses Composer autoloader
require BASE_DIR . '/vendor/autoload.php';
// start session
session_start();
return require SRC_DIR . '/config/config.php';

Example reading / writing to a CSV file

<?php
if (!$fh = fopen('people.csv', 'r+')) exit('Unable to open file');

$data = [];
while (!feof($fh)) {
    $data[] = fgetcsv($fh);
}
fclose($fh);

if (!$fh = fopen('people.csv', 'a')) exit('Unable to open file');
fputcsv($fh, ['Fred', 'M']);
readfile('people.csv');

You can use readfile() to output a PDF

Example of a web script that searches a text file for a given string:

<?php
// Example using `file()` to search a text file for an item
// Returns the line number
$fn = __DIR__ . '/example.txt';
$list = file($fn);
// use `strip_tags()` to sanitize the input
$search = strip_tags($_GET['search'] ?? 'Default');
$found = 0;
foreach ($list as $num => $item) {
	if (str_contains(strtolower($item), $search)) {
		echo htmlspecialchars($search) . ' was found in ' . basename($fn) . ' on line ' . ++$num . "\n";
		$found++;
		break;
	}
}
if ($found === 0) {
	// use `htmlspecialchars()` to "escape" the output
	echo htmlspecialchars($search) . ' was not found in ' . basename($fn) . "\n";
}
?>
<form>Search For: <input type"text" name="search" /><input type="submit" /></form>

Example of a web script that records user selection and then does a redirect

<?php
if (!empty($_GET)) {
	// get input info
	$ip = $_SERVER['REMOTE_ADDR'] ?? 'Unknown';
	$lang = $_SERVER['HTTP_ACCEPT_LANGUAGE'] ?? 'en';
	$agent = $_SERVER['HTTP_USER_AGENT'] ?? 'Unknown';
	$fh = fopen('test.csv', 'a');
	// determine target
	$target = match($_GET['target']) {
		'zend' => 'https://zend.com',
		'unlikely' => 'https://unlikelysource.com',
		'ibm' => 'https://ibm.com',
		default => ''
	};
	// record user select
	fputcsv($fh, [$ip, $target, $lang, $agent, date('Y-m-d H:i:s')]);
	fclose($fh);
	// redirect to target
	if (!empty($target)) {
		header('Location: ' . $target);
		exit;
	}
}
?>
<h1>Destinations</h1>
<a href="/test.php?target=zend">Zend</a>
<br />
<a href="/test.php?target=unlikely">Unlikelysource.com</a>
<br />
<a href="/test.php?target=ibm">IBM</a>

Example of output escaping:

<?php
if (!empty($_POST)) {
	// strip_tags() here would actually alter the input data
	// $name = strip_tags($_POST['item']);
	$name = $_POST['item'];
}
?>
<form action="test.php" method="post">
    <fieldset>
        <legend>Add Checklist Item</legend>
        <label for="item">Enter the checklist item</label>
        <input type="text" name="item" id="item">
        <label for="priority">Enter the priority</label>
        <input type="text" name="priority" id="priority">
        <input type="submit" value="Submit">
    </fieldset>
</form>
<!-- this safeguards output, but doesn't remove characters -->
<?= 'The item you entered is: ' . htmlspecialchars($name); ?>

If you need to adjust the amount of data to send on your server:

Example using cookies:

Database

Sample SQL query for use in the VM:

SELECT c.id, c.firstname, c.lastname, o.id AS order_id, o.date, o.status, o.amount, o.description
FROM customers AS c
JOIN orders AS o ON c.id = o.customer
WHERE c.id = 3;
  • output:
id	firstname	lastname	order_id	date	status	amount	description
3	J	Flores	2	1359062345	invoiced	9800
3	J	Flores	4	1359500400	open	34	Paper
3	J	Flores	7	1360796400	open	300	A big box of chocolates.
3	J	Flores	8	1685102423	open	400	office chair
3	J	Flores	9	1685102435	open	400	office chair

Example retrieving results from the VM database:

$config = [
    //The database access credentials
    'db' => [
        'dsn' => '127.0.0.1',
        'username' => 'vagrant',
        'password' => 'vagrant',
        'database' => 'phpcourse'
    ]
];
$conn = mysqli_connect($config['db']['dsn'], $config['db']['username'],
        $config['db']['password'], $config['db']['database']);

$sql = 'SELECT * FROM customers AS c JOIN orders AS o On c.id = o.customer';
$query = mysqli_query($conn, $sql);
while ($row = mysqli_fetch_assoc($query)) {
	echo implode("\t", $row);
}

Example collecting data from a form and inserting into the database:

<?php
$item = '';
$priority = 0;
if(!empty($_POST)) {
    $item = $_POST['item'] ?? '';
    $id   = $_POST['id'] ?? '';
    $qty  = $_POST['qty'] ?? '';
    if(!empty($item) && !empty($id) && !empty($qty)) {
        $item = filter_var(strip_tags($item), FILTER_SANITIZE_STRING);
        $id = (int) $id;
        $qty = (int) $qty;
        echo 'Data is validated and sanitized, handle it ...';
		$config = [
			//The database access credentials
			'db' => [
				'dsn' => '127.0.0.1',
				'username' => 'vagrant',
				'password' => 'vagrant',
				'database' => 'phpcourse'
			]
		];
		$conn = mysqli_connect($config['db']['dsn'], $config['db']['username'],
				$config['db']['password'], $config['db']['database']);

		$sql = 'INSERT INTO orders (date, status, amount, description, customer) '
		     . 'VALUES (' . time() . ',\'open\',' . $qty . ',\'' . $item . '\',' . $id . ')';
		echo '<br />';
		echo (mysqli_query($conn, $sql)) ? 'Success' : 'Failed';

    } else {
        echo 'Invalid input';
        exit;
    }
} else {
    // no form data has been posted
    echo 'No form data has been posted';
}
?>
<form action="test.php" method="post">
    <fieldset>
        <legend>Order</legend>
        <label for="item">Item</label>
        <input type="text" name="item" id="item">
        <label for="id">Customer ID</label>
        <input type="text" name="id" id="id">
        <label for="qty">Quantity</label>
        <input type="text" name="qty" id="qty">
        <input type="submit" value="Submit">
    </fieldset>
</form>

Tools

To facilitate debugging at runtime:

error_log(__FILE__ . ':' . __LINE__ ':' . var_export($variable, TRUE));

Update/Upgrade the VM

sudo dpkg --configure -a
sudo apt -y update && sudo apt -f -y install && sudo apt -y full-upgrade
  • Apache reconfig:
sudo apt-add-repository ppa:ondrej/apache2
sudo apt install libapache2-mod-php8.2
sudo a2dismod php8.0
sudo systemctl restart apache2
sudo a2enmod php8.2
sudo systemctl restart apache2

Q & A

Resources

Automatic documentation generation

Errata