How Can I Efficiently Obtain the Base URL in PHP?

Obtaining the Base URL with PHP

In web development environments like PHP, obtaining the base URL can be essential for various purposes. This article explores how to achieve this task effectively.

To retrieve the base URL, the recommended approach is to utilize the $_SERVER predefined variable. By combining the SERVER_NAME and REQUEST_URI keys, this method provides a reliable and accurate way to construct the base URL. Here's an example implementation:

<?php echo "http://" . $_SERVER['SERVER_NAME'] . $_SERVER['REQUEST_URI']; ?>

This straightforward code concatenates the protocol (http://), server name (127.0.0.1), and request URI (/test_website/) to produce the base URL: http://127.0.0.1/test_website/.

For situations where HTTPS is involved, a modified function called url() can be employed:

function url(){
  return sprintf(
    "%s://%s%s",
    isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] != 'off' ? 'https' : 'http',
    $_SERVER['SERVER_NAME'],
    $_SERVER['REQUEST_URI']
  );
}
echo url();
#=> http://127.0.0.1/foo

To ensure reliable usage of the SERVER_NAME key, it's vital to configure Apache appropriately. The following configuration snippet exemplifies this setup:

<virtualhost>
    ServerName example.com
    UseCanonicalName on
</virtualhost>

Additionally, if relying on the HTTP_HOST key, caution should be taken to sanitize user input before usage. The PHP parse_url function offers a comprehensive example of handling such data.

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