PHP Development

Classes
Traits
File system
Form handling
Project structure
PHP MySQL

Classes

Classes are the blueprint for objects.
Objects are instances of classes.
Classes can have properties and methods.

<?php
  class Car {
    public $color;
    public $model;
  }

  $car1 = new Car();
  $car1->color = "red";
  $car1->model = "Toyota";

  echo $car1->color; // red
  echo $car1->model; // Toyota
?>

Properties

Properties are variables that hold data.
Properties are declared with the public, protected, or private keyword.
Properties can have default values.

<?php
  class Car {
    public $color = "red";
    public $model = "Toyota";
    protected $year = 2021;
    private $price = 10000;
  }

  $car1 = new Car();
  echo $car1->color; // red
  echo $car1->model; // Toyota
  echo $car1->year; // Fatal error: Uncaught Error: Cannot access protected property Car::$year
  echo $car1->price; // Fatal error: Uncaught Error: Cannot access private property Car::$price
?>

<?php
  class Car {
    private $model;

    public function setModel($model) {
      $this->model = $model;
    }

    public function getModel() {
      return $this->model;
    }
  }

  $car1 = new Car();
  $car1->setModel("Toyota");
  echo $car1->getModel(); // Toyota
?>

<?php
  class Car {
    protected $model;

    public function setModel($model) {
      $this->model = $model;
    }

    public function getModel() {
      return $this->model;
    }
  }

  class Toyota extends Car {
    public function showModel() {
      return $this->model;
    }
  }

  $toyota = new Toyota();
  $toyota->setModel("Toyota");
  echo $toyota->getModel(); // Toyota
  echo $toyota->showModel(); // Toyota
?>

The protected keyword allows the property to be accessed by the class and its subclasses.
The private keyword allows the property to be accessed only by the class.
The public keyword allows the property to be accessed by any class.

Traits

Traits are used to group functionality in a fine-grained and consistent way.
Traits are similar to classes, but they are intended to group functionality in a fine-grained way.

<?php
  trait Drivable {
    public function drive() {
      echo "Driving...";
    }
  }

  class Toyota {
    use Drivable;
  }

  $toyota = new Toyota();
  $toyota->drive(); // Driving...
?>

Form Handling

Form handling is the process of capturing user input from a web form.
The $_GET and $_POST superglobals are used to collect form data.
The $_GET method is used to collect form data after submitting an HTML form with the GET method.
The $_POST method is used to collect form data after submitting an HTML form with the POST method.

<?php
  if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $name = $_POST["name"];
    $email = $_POST["email"];
    echo "Name: $name, Email: $email";
  }
?>

<form method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>">
  Name: <input type="text" name="name"><br>
  Email: <input type="text" name="email"><br>
  <input type="submit">
</form>

The $_REQUEST superglobal is used to collect form data after submitting an HTML form.
The $_REQUEST method can collect data from both the GET and POST methods.

<?php
  if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $name = $_REQUEST["name"];
    $email = $_REQUEST["email"];
    echo "Name: $name, Email: $email";
  }
?>

<form method="get" action="<?php echo $_SERVER['PHP_SELF']; ?>">
  Name: <input type="text" name="name"><br>
  Email: <input type="text" name="email"><br>
  <input type="submit">
</form>

File System

PHP has several functions for creating, reading, updating, and deleting files.
The fopen() function is used to open a file.
The fwrite() function is used to write to a file.
The fclose() function is used to close a file.

<?php
  $file = fopen("file.txt", "w");
  fwrite($file, "Hello, World!");
  fclose($file);
?>

The fread() function is used to read a file.
The feof() function is used to check if the end of a file has been reached.

<?php
  $file = fopen("file.txt", "r");
  while (!feof($file)) {
    echo fgets($file);
  }
  fclose($file);
?>

Save array to csv

<?php
  $data = array(
    array("John", "Doe", 25),
    array("Jane", "Smith", 30)
  );

  $file = fopen("file.csv", "w");
  foreach ($data as $row) {
    fputcsv($file, $row);
  }
  fclose($file);
?>

Read csv

<?php
  $file = fopen("file.csv", "r");
  while (($row = fgetcsv($file)) !== false) {
    print_r($row);
  }
  fclose($file);
?>

Save array to json

<?php
  $data = array(
    array("name" => "John", "age" => 25),
    array("name" => "Jane", "age" => 30)
  );

  $json = json_encode($data);
  file_put_contents("file.json", $json);
?>

Read json

<?php
  $json = file_get_contents("file.json");
  $data = json_decode($json, true);
  print_r($data);
?>

Project Structure

A typical PHP project structure might look like this:

project/
├── app/
│   ├── controllers/
│   ├── models/
│   ├── views/
├── public/
│   ├── css/
│   ├── js/
│   ├── index.php
├── vendor/
├── composer.json
├── composer.lock

The app directory contains the application code.
The public directory contains the public files (e.g., CSS, JavaScript, images).
The vendor directory contains the third-party libraries.
The composer.json file contains the project dependencies.
The composer.lock file contains the exact versions of the dependencies.
The index.php file is the entry point of the application.
The controllers directory contains the controller classes.
The models directory contains the model classes.
The views directory contains the view files.
The css directory contains the CSS files.
The js directory contains the JavaScript files.

Use Composer

Composer is a dependency manager for PHP.
Composer is used to manage the project dependencies.
Composer is used to autoload the classes.

composer require monolog/monolog

<?php
  require 'vendor/autoload.php';

  use Monolog\Level;
  use Monolog\Logger;
  use Monolog\Handler\StreamHandler;

  $log = new Logger('name');
  $log->pushHandler(new StreamHandler('app.log', Level::Warning));

  $log->warning('Foo', ['foo' => 'bar']);
  $log->error('Bar', ['bar' => 'foo']);
?>

PHP MySQL

PHP can be used to interact with MySQL databases.
The mysqli extension is used to connect to MySQL databases.
The mysqli_connect() function is used to connect to a MySQL database.
The mysqli_query() function is used to execute a SQL query.
The mysqli_fetch_assoc() function is used to fetch a result row as an associative array.

<?php
  $conn = mysqli_connect("localhost", "root", "", "test");

  if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
  }

  $sql = "SELECT * FROM users";
  $result = mysqli_query($conn, $sql);

  if (mysqli_num_rows($result) > 0) {
    while ($row = mysqli_fetch_assoc($result)) {
      print_r($row);
    }
  }

  mysqli_close($conn);
?>

The mysqli_real_escape_string() function is used to escape special characters in a string.
The mysqli_insert_id() function is used to get the ID generated in the last query.

<?php
  $name = mysqli_real_escape_string($conn, $_POST['name']);
  $email = mysqli_real_escape_string($conn, $_POST['email']);

  $sql = "INSERT INTO users (name, email) VALUES ('$name', '$email')";

  if (mysqli_query($conn, $sql)) {
    $last_id = mysqli_insert_id($conn);
    echo "New record created successfully. Last inserted ID is: " . $last_id;
  } else {
    echo "Error: " . $sql . "<br>" . mysqli_error($conn);
  }
?>

The mysqli_error() function is used to get the last error message.
The mysqli_close() function is used to close the connection.
The mysqli_num_rows() function is used to get the number of rows in a result set.
The mysqli_fetch_array() function is used to fetch a result row as an associative array, a numeric array, or both.

<?php
  $sql = "SELECT * FROM users";
  $result = mysqli_query($conn, $sql);

  if (mysqli_num_rows($result) > 0) {
    while ($row = mysqli_fetch_array($result)) {
      print_r($row);
    }
  }
?>

The mysqli_fetch_row() function is used to fetch a result row as a numeric array.
The mysqli_fetch_object() function is used to fetch a result row as an object.

<?php
  $sql = "SELECT * FROM users";
  $result = mysqli_query($conn, $sql);

  if (mysqli_num_rows($result) > 0) {
    while ($row = mysqli_fetch_object($result)) {
      print_r($row);
    }
  }
?>

The mysqli_fetch_all() function is used to fetch all result rows as an associative array.
The mysqli_fetch_assoc() function is used to fetch a result row as an associative array.
The mysqli_fetch_array() function is used to fetch a result row as an associative array, a numeric array, or both.

<?php
  $sql = "SELECT * FROM users";
  $result = mysqli_query($conn, $sql);

  $rows = mysqli_fetch_all($result, MYSQLI_ASSOC);
  print_r($rows);
?>

Prepared Statements

Prepared statements are used to execute the same SQL query repeatedly with high efficiency.
Prepared statements are used to prevent SQL injection attacks.

<?php
  $stmt = $conn->prepare("INSERT INTO users (name, email) VALUES (?, ?)");
  $stmt->bind_param("ss", $name, $email);

  $name = "John";
  $email = "john@doe.com";
  $stmt->execute();
  
  $name = "Jane";
  $email = "jane@doe.com";
  $stmt->execute();

  $stmt->close();
?>

The bind_param() function is used to bind variables to a prepared statement.
The execute() function is used to execute a prepared statement.
The close() function is used to close a prepared statement.
The bind_result() function is used to bind result variables to a prepared statement.

<?php
  $stmt = $conn->prepare("SELECT name, email FROM users WHERE id = ?");
  $stmt->bind_param("i", $id);

  $id = 1;
  $stmt->execute();
  $stmt->bind_result($name, $email);

  while ($stmt->fetch()) {
    echo "Name: $name, Email: $email";
  }

  $stmt->close();
?>

MySQL Security

Use prepared statements to prevent SQL injection attacks.
Use mysqli_real_escape_string() to escape special characters in a string.
Use htmlspecialchars() to prevent XSS attacks.

<?php
  $name = mysqli_real_escape_string($conn, $_POST['name']);
  $email = mysqli_real_escape_string($conn, $_POST['email']);

  $sql = "INSERT INTO users (name, email) VALUES ('$name', '$email')";
?>

<?php
  $name = htmlspecialchars($_POST['name']);
  $email = htmlspecialchars($_POST['email']);

  $sql = "INSERT INTO users (name, email) VALUES ('$name', '$email')";
?>

Applying both mysqli_real_escape_string() and htmlspecialchars() is the best practice. Creating a function to escape special characters and prevent XSS attacks.

<?php
  function escape($conn, $value) {
    return htmlspecialchars(mysqli_real_escape_string($conn, $value));
  }

  $name = escape($conn, $_POST['name']);
  $email = escape($conn, $_POST['email']);

  $sql = "INSERT INTO users (name, email) VALUES ('$name', '$email')";
?>

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

SESSION_02.md

SESSION_02.md

PHP Development

Classes

Properties

Traits

Form Handling

File System

Save array to csv

Read csv

Save array to json

Read json

Project Structure

Use Composer

PHP MySQL

Prepared Statements

MySQL Security

Files

SESSION_02.md

Latest commit

History

SESSION_02.md

File metadata and controls

PHP Development

Classes

Properties

Traits

Form Handling

File System

Save array to csv

Read csv

Save array to json

Read json

Project Structure

Use Composer

PHP MySQL

Prepared Statements

MySQL Security