How to Create Routing in PHP

ByMax Pronko

Ever wondered how to create PHP routing to handle different requests? Let’s create a custom php function that is going to find the route and process an HTTP GET request in its callback function. We are going to have an exercise where you can practice your skills in creating routes.

Creating Routes

In the routes.php file let’s create an array of routes. A key will be a route, and a value is a callback function that will be triggered to process the route.

The routes.php file:

<?php

return [
    '/' => function () {
        echo '<h1>Home Page</h1>';
    },
    '/login' => function (array $params) {
        echo '<h1>Login Page</h1>';
    },
];

For the first route, we are going to echo Home Page. Let’s also create a login route with the Login Page title.

Creating the run() function

In the functions.php file, we are going to have a function that will process the routes array from the routes.php file. I am going to call the function run and pass URLs and routes. First of all, we should parse the url argument. For this, let’s call a parse_url function and pass url. As a result, we can get the path from the URL that can be used to check if the path is a key of the routes array.

In case of a match, we can get a callback function and call it as a result of the run function.

<?php

function run(string $url, array $routes): void
{
    $uri = parse_url($url);
    $path = $uri['path'];
    if (false === array_key_exists($uri['path'], $routes)) {
        return;
    }

    $callback = $routes[$path];
    $callback();
}

Putting routes and run() functions together

In the index.php file is the main application entry point, we should include the functions.php file and the routes array that is located in the routes.php file. Next, we can trigger the run function and pass the REQUEST_URI value from the $_SERVER array as a first argument, and routes as a second.

<?php
include_once 'functions.php';

$routes = include_once 'routes.php';

run($_SERVER['REQUEST_URI'], $routes);

Passing parameters from URL query into the callback function

Sometimes we need to pass extra parameters from url. To do this, let’s modify the run function. We can read the query value from the URI array prepared earlier by the parse_url function and call parse_str for the query. As a result, we will get a key-value pair array of parameters that we can pass to the callback function.

In the login callback function, we should add an argument for parameters. We can refer to the name of the parameter we would like to render on the login page. I will render a name for the Welcome message. Let’s also render parameters.

function run(string $url, array $routes): void
{
    $uri = parse_url($url);
    $path = $uri['path'];
    if (false === array_key_exists($uri['path'], $routes)) {
        return;
    }

    $callback = $routes[$path];
    $params = [];
    if (!empty($uri['query'])) {
        parse_str($uri['query'], $params);
    }
    $callback($params);
}

Homework Exercise

Time for practice. To better memorize the routing approach and get some practical experience here is the exercise for you. Add a new logout route that will redirect a user to the login page and show the optional message “You have been successfully logged out”. A small hint, you should use the header() php function and include a query parameter for the message. Do not include the message in the query.

Adding a logout route

Let’s add a new logout route after the login route in the routes.php file. We can access the route via /logout uri and the callback function should call a header function with the location to the login route. Also, we should include a query parameter that will help to identify the redirect from logout route.

<?php

return [
    '/' => function () {
        echo '<h1>Home Page</h1>';
    },
    '/login' => function (array $params) {
        echo '<h1>Login Page</h1>';
    },
    '/logout' => function () {
        header('Location: /login?success=true');
    }
];

In the login route, let’s check if there is a success key in the params array and let’s show a message and don’t forget to add a return statement to exit the function.

<?php

return [
    '/' => function () {
        echo '<h1>Home Page</h1>';
    },
    '/login' => function (array $params) {
        echo '<h1>Login Page</h1>';
        if (!empty($params['success'])) {
            echo 'You have been successfully logged out!';
            return;
        }
        echo '<p>Welcome, ' . ucfirst($params['name'] ?? 'guest') . '!</p>';
        echo '<pre>';
        print_r($params);
    },
    '/logout' => function () {
        header('Location: /login?success=true');
    }
];

Video Tutorial

Watch the video tutorial on how to create a PHP Routing and execute it in your local environment.

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