Intro to PHP Templating & Some Helper Functions

Matt Toegel matthew.toegel@njit.edu

Prelude

Requires the lessons up to and including Navigation & Login Part 2 to have been completed

  • Checkout Milestone1

    • Pull any latest changes

  • Create a new branch Feat-MS1-HelperFunctions

Helper Functions

  • Let’s work on modularizing our code to avoid lengthy and repetitive code

  • We’ll update our functions.php to include some helper functions

  • Then we’ll make two new files in the lib folder to hold our sanitizers/validations and user helpers

  • Inside the lib folder, create a new file called validations.php and another called user_helpers.php

  • The sub-sections will cover the contents of these files

functions.php

<?php
//TODO 1: require db.php
require(__DIR__ . "/db.php");
//require safer_echo.php
require(__DIR__ . "/safer_echo.php");
//TODO 2: filter helpers
require(__DIR__ . "/validations.php");
//TODO 3: User helpers
require(__DIR__ . "/user_helpers.php");
//TODO 4: Flash Message Helpers
?>

Link: https://gist.github.com/MattToegel/6a1227064a115a10d02be8be30302550

  • Pulls in the validations.php (TODO 2) and user_helpers.php (TODO 3) files via require()

validations.php

<?php

function sanitize_email($email = "") {
    return filter_var(trim($email), FILTER_SANITIZE_EMAIL);
}
function is_valid_email($email = "") {
    return filter_var(trim($email), FILTER_VALIDATE_EMAIL);
}

Link: https://gist.github.com/MattToegel/718a5d781a3688c79551f7390f53574c

  • Contains reusable email validation/sanitization functions

    • Uses the filter_var() function to validate and sanitize email addresses

This encapsulation allows us to easily update the email validation logic in one place, ensuring consistency across the application.

user_helpers.php

<?php
/**
 * Checks if user key is set in session
 */
function is_logged_in() {
    return isset($_SESSION["user"]);
}
/**
 * Returns the current user's username or empty string
 */
function get_username() {
    if (is_logged_in()) { //we need to check for login first because "user" key may not exist
        return se($_SESSION["user"], "username", "", false);
    }
    return "";
}
/**
 * Returns the current user's email or empty string
 */
function get_user_email() {
    if (is_logged_in()) { //we need to check for login first because "user" key may not exist
        return se($_SESSION["user"], "email", "", false);
    }
    return "";
}
/**
 * Returns the current user's id or -1
 */
function get_user_id() {
    if (is_logged_in()) { //we need to check for login first because "user" key may not exist
        return se($_SESSION["user"], "id", -1, false);
    }
    return -1;
}

Link: https://gist.github.com/MattToegel/98dc5ad3b81ece0c22bb336a6c88f389

  • Contains the following helpers

    • is_logged_in(): Checks if the user is logged in by verifying the session

    • get_username(): Returns the username of the logged-in user

    • get_user_email(): Returns the email of the logged-in user

    • get_user_id(): Returns the ID of the logged-in user

  • These functions simplify access to user data and ensure that we don’t have to repeatedly check the session or database for this information

Putting the Helpers to Use

  • In register.php and login.php, replace the email validation/sanitization with the helper functions we just added (screenshot 1)

  • This ensures consistency between both pages since they both refer to a single function for this functionality

  • In landing.php, change it to what’s in screenshot 2

    • Now anywhere we need to use this data, we can easily use our helper functions to simplify development

As you develop your project, look for functionality you replicate often, these are likely candidates to extract into a function for reusability
Screenshot 1 (login/register)Screenshot 2 (landing)

sanitize email

welcome helper 2

PHP Templating: Conditional HTML

  • PHP templating smoothly mixes our PHP and HTML via conditional statements

    • PHP tags can be placed throughout the page, allowing conditional HTML output (if the expression is true, the HTML is sent to the browser)

  • We’ll use core PHP mechanics instead of a templating engine; but it still allows our IDE to properly validate both PHP and HTML

  • Major benefits include:

    • Reusability

    • Better syntax validation

Always sanitize user input before outputting it to the browser. Remember, our se()/safer_echo() function does this for us, so use it whenever you output user data. But normally you would use htmlspecialchars()

Implementing Templating in nav.php

  • Go to your nav.php and update its content with:

<nav>
    <ul>
        <!-- new content below -->
        <?php if (is_logged_in()) : ?> (1)
            <li><a href="landing.php">Home</a></li>
        <?php endif; ?> (2)
        <?php if (!is_logged_in()) : ?>
            <li><a href="login.php">Login</a></li>
            <li><a href="register.php">Register</a></li>
        <?php endif; ?>
        <?php if (is_logged_in()) : ?>
            <li><a href="logout.php">Logout</a></li>
        <?php endif; ?>
    </ul>
</nav>

Link: https://gist.github.com/MattToegel/89530d5559497008fe7700dc94f3bf2d

1The navigation links are conditionally displayed based on the user’s logged-in state
2The HTML is not sent to the browser if the condition is false

  • Adjustments will be made later for links available only to certain user roles

  • We’ll see more templating as we proceed; in the meantime ensure you follow proper syntax for a clean combination of PHP and HTML

  • Try logging and and logging out and note the changes in the navigation bar

Summary

  • This lesson was about preparing to work smarter by building reusable components via functions, partial files, or both

  • Reusability centralizes logic, making future changes easier

  • Going forward, you’ll need to implement similar concepts

  • Add and commit these changes to Feat-MS1-HelperFunctions, push the changes to GitHub, and create a pull request to Milestone1.

    • git add .

    • git commit -m "added helper functions and templating for navigation"

    • git push origin Feat-MS1-HelperFunctions

  • Finally, merge and pull the latest changes from Milestone1

    • git checkout Milestone1

    • git pull origin Milestone1

  • Checkpoint: https://github.com/MattToegel/IT202-2025/tree/Module04-HelperFunctions

    • Note: My branch name differs from yours so I can isolate the lesson content