Get root URL for a PHP website

Question

I'm currently working on a PHP project and am looking for a way to get the URL for the root of the website; I have a configuration file at the root so I'm thinking as to using that to figure out the "base URL." I'm looking for a way to do it dynamically so I can locate the URL of the root of the website, i.e. http://domain.com/my_app/. I am doing my best to avoid using relative paths and am using PHP to generate the URLs for whatever I am using. For example, I am using PHP to generate CSS code and the CSS code link to images so I would like to get an absolute URL in here instead of a relative path.

my_app/
    admin/
        resources/
            css/
                admin-css.php
            imgs/
                login.png
    resources/
        css/
            css.php
        imgs/
            my-image.png
            shared-image.png
    config.php

In my resources/css/css.php file, I am looking at getting the "base URL" so I can generate an absolute URL to the imgs folder like http://domain.com/resources/imgs/my-image.png but currently I am getting http://domain.com/resources/css/imgs/my-image.png since the defines below look at getting the directory of the loaded PHP file, not the included one. I would also like to share images between the folders (i.e. access the shared-image.png file from the admin folder) so getting the base URL would be ideal in generating links. The reason I an avoiding relative paths is because I have a function that creates a URL, createURL(), so I can get all the URLs working without having to hard code anything.

<?php
DEFINE('HTTP_TYPE', $_SERVER['HTTP_X_FORWARDED_PROTO']);
DEFINE('HTTP_ROOT', $_SERVER['HTTP_HOST']);
DEFINE('HTTP_FOLDER', dirname($_SERVER['PHP_SELF']) . '/');
DEFINE('BASE_URL', HTTP_TYPE . "://" . HTTP_ROOT . HTTP_FOLDER);

function createURL($pathFromRoot)
{
    return BASE_URL . $pathFromRoot;
}

All of these defines are located in my configuration file, so I am thinking that the best way to do this is to get the URL for the config file (http://domain.com/my_app/config.php) and just strip the "config.php." Keep in mind, the website could be hosted deeper in a folder structure http://domain.com/my_app/another/folder/config.php or no sub folders http://domain.com/config.php.

Is this possible, if so how can it be done? Or is there another approach I should follow?

Answer 1

After doing a var_dump of $_SERVER and messing around I found that I could generate the base URL with this solution, in case anyone stumbles upon this question. I'm sure there are other ways but this is what worked for me.

<?php
DEFINE('BASE_URL', HTTP_TYPE . "://" . HTTP_ROOT . substr(__DIR__, strlen($_SERVER[ 'DOCUMENT_ROOT' ])) . '/');

Answer 2

I just needed the same thing I combined the answers from here and here to create this solution which can be easily converted to multiple constants and/or a function. I use a single entry point for my web application (index.php) and have my config in a sub-folder. You can either strip the known folder as shown in the commented line of code or run this from the main folder. As example your structure could be either/or of:

• /public/html/some/random/folders/THEAPP/config.php
  • $urlDir = str_replace($docRoot, '', $dirRoot);

or

• /public/html/some/random/folders/THEAPP/include/config.php
  • $urlDir = str_replace('/include', '/',str_replace($docRoot, '', $dirRoot));

Entire Code:

$domain = $_SERVER['HTTP_HOST'];
$docRoot = $_SERVER['DOCUMENT_ROOT'];
$dirRoot = dirname(__FILE__);
$protocol = isset($_SERVER["HTTPS"]) ? 'https://' : 'http://';
//$urlDir = str_replace('/include', '/',str_replace($docRoot, '', $dirRoot));
$urlDir = str_replace($docRoot, '', $dirRoot);
$site_path = $protocol.$domain.$urlDir;
define ('BASE_URL', $site_path);

Based server configurations: The output may not contain a trailing slash / if wanted then use either of:

• $urlDir = str_replace('/include', '/',str_replace($docRoot, '/', $dirRoot));
• $urlDir = str_replace($docRoot, '/', $dirRoot);

BTW, the function seems unnecessary as example:

function createURL($pathFromRoot)
{
    return BASE_URL . $pathFromRoot;
}

//Anywhere you can call `createURL($value)` makes the following true
$isTrue = createURL('/static/js/my.js') === BASE_URL.'/static/js/my.js';
$someNeededURL = '/static/whatever/is/converted/';
$alsoTrue = createURL($someNeededURL) === BASE_URL.$someNeededURL;
//and just for fun
if ($isTrue.$alsoTrue === 11){
    echo 'Not eleven';
    } else {
        echo $isTrue.$alsoTrue.'!==11';
    };