php.md

PHP

Logic

The null coalescing operator lets you say succinctly "Use $a if it exists, otherwise use $b." Like this:

$x = $a ?? 'b'; // same as $x = isset($a) ? $a : 'b'
$build_file = $_REQUEST["build"] ?? $_REQUEST["file"] ?? "index.html";

Forms

<form action="processForm.php" method="post">
    <label>Name <input type="text" name="name" placeholder="John Smith"></label>
    <label>Comment <textarea name="comment" placeholder="What's up?"></textarea></label>
    <input type="submit" name="submit" />
</form>

<?php // processForm.php
    if (isset($_POST['submit'])) {
        echo "It works!";
    }
?>

Databases

<?php
    $connection = mysqli_connect($serverAddress, $username, $password, $dbName);
    if ($connection) {
        echo 'Logged in';
    } else {
        die('Database connection failed');
    }
?>

Passwords

<?php

$connection = mysqli_connect($serverAddress, $username, $password, $dbName);
if (!$connection) die('Database connection failed');

if(isset($_POST['submit'])) {
    $username = $_POST['username'];
    $password = $_POST['password'];
    $username = mysqli_real_escape_string($connection, $username);
    $password = mysqli_real_escape_string($connection, $password);
    $password = password_hash($password, PASSWORD_DEFAULT);

    $query = "INSERT INTO users(username, password) VALUES ('$username', '$password')";
    $result = mysqli_query($connection, $query);
    if (!$result) {
        die('Query failed ' . mysqli_error()); 
    } else {
        echo "Record created";
    }
}

?>

Cookies

Setting cookies

$minute = 60;
$hour = $minute * 60;
$day = $hour * 24;
$year = $day * 365;
$expiration = time() + $year * 2;
setcookie($cookieName, $cookieValue, $expiration);

Reading cookies

$myCookie = $_COOKIE["NameOfCookie"];
if (isset($myCookie)) {
    echo $myCookie;
}

File I/O

Reading

$file = fopen('filename.txt', 'r'); // 'r' for 'read'
echo fread($file, 10); // read first 10 characters
echo fread($file, filesize('filename.txt')); // read entire file
fclose($file);

Writing

$file = fopen('filename.txt', 'w'); // 'w' for 'write'. Warning: entire file will be overwritten.
fwrite($file, 'Write this text to the file');
fclose($file);

See the "mode" flags in the fopen() documentation.

Erasing

unlink("doomed-file.txt");

Secrets

<?php // includes/db.php

$secretsFile = file_get_contents('../secrets.json');
$secretsJson = json_decode($secretsFile, true);
$dbSecrets = $secretsJson['db'];

$connection = mysqli_connect($dbSecrets['ip'], $dbSecrets['username'], $dbSecrets['password'], $dbSecrets['name']);

if (!$connection) { die("Database connection failed"); }

?>

// .gitignore
secrets.json