Change href based on URI using PHP - php

Question

I'm trying to make a main menu bar link dynamic, based on the visitor's current page.
I started with
$path = $_SERVER['REQUEST_URI'];
Which, of course, returns things like
/subfolder/page.html
/subfolder1/subfolder2/page.html
/page.html
I need to grab whatever is after the first '/'. I've tried messing around with explode, but I stumble with what to do with the resulting array. I'm also going cross-eyed trying to write a regex - seems a more elegant solution.
Then I need to build my switch. Something along the lines of:
switch ($path)
{
case '/subfolder0':
$link = $root_url.'/subfolder0/anotherfolder/page.html';
break;
case '/subfolder1':
$link = $root_url.'/subfolder1/page.html';
break;
default:
$link = $root_url.'/subfolder2/page.html';
}
Finally, should I be using if...elseif for this in lieu of switch?
Thanks for your time, all!

Answer 1

To grab everything after the first /:
strstr($_SERVER['REQUEST_URI'], '/');
Or, with regex:
preg_match('#(/.*)#', $_SERVER['REQUEST_URI'], $matches); // $matches[1] will be the path
As far as the switch, I'd say if/elseif/else is the least-elegant in your case, switch isn't bad, but personally I'd go with an associative array:
$mapping = array('/subfolder0' => $root_url.'/subfolder0/anotherfolder/page.html', 'etc' => 'etc');
$link = $mapping($path);
This lets you keep the mapping in another file for organization, and makes it a little bit easier to maintain by separating configuration from implementation.

Answer 2

Using explode is not at all a bad idea if you are interested in all the parts of the URI, you should take a look at the documentation for explode
Its usage would be like so:
$exploded = explode('/','/path/to/page.html');
echo $exploded[0]; // Will print out '' (empty string)
echo $exploded[1]; // Will print out 'path'
echo $exploded[2]; // Will print out 'to'
echo $exploded[3]; // Will print out 'page.html'
However as far as I understand, you are looking to replace the link by whatever is after the first character (which is always '/'), you could use substr like so:
// Get whatever is after the first character and put it into $path
$path = substr($_SERVER['REQUEST_URI'], 1);
In your case, it is not needed because you are able to predict there is a backslash at the beginning of the string.
I would also suggest using an associative array to replace the URL.
I would implement the entire thing like so (removing the first backslash as you require):
// Define the URLs for replacement
$urls = array(
'subfolder0' => '/subfolder0/anotherfolder/page.html',
'subfolder1' => '/subfolder1/page.html'
);
// Get the request URI, trimming its first character (always '/')
$path = substr($_SERVER['REQUEST_URI'], 1);
// Set the link according to $urls associative array, or set
// the default URL if not found
$link = $urls[$path] or '/subfolder2/page.html';
Or with explode, taking only the first part of the URI:
// Get the parts of the request
$requestParts = explode('/', $_SERVER['REQUEST_URI']);
// Set the link according to $urls associative array, or set
// the default URL if not found
$link = $urls[$requestParts[1]] or '/subfolder2/page.html';

Answer 3

After analyzing the OP's question, I think he/she meant to phrase it as "Everything after the first '/', but before the second '/'. Here is what I got:
You could try this regex:
<?php
/*
* Regex: /((\w+?|\w+\.\w+?)(?!^\/))(?=\/.*$|$)/
*/
$paths = array(
'/subfolder9/',
'/subfolder/page.html',
'/subfolder1/subfolder2/page.html',
'/page.html'
);
foreach ($paths as $path) {
preg_match("/((\w+?|\w+\.\w+?)(?!^\/))(?=\/.*$|$)/", $path, $matches);
debug($matches);
}
// $matches[1] will contain the first group ( ) matched in the expression.
// or "subfolder<#>" or "<page>.<ext>"
// The loop results is as follows:
Array
(
[0] => subfolder9
[1] => subfolder9
[2] => subfolder9
)
Array
(
[0] => subfolder
[1] => subfolder
[2] => subfolder
)
Array
(
[0] => subfolder1
[1] => subfolder1
[2] => subfolder1
)
Array
(
[0] => page.html
[1] => page.html
[2] => page.html
)
?>
Note: This only works with regex flavors that support look-arounds (zero-width positive & negative look ahead are the ones used the example.)
This a great cheat sheet for regular expressions and I don't code without it.
Regular-Expressions.info - (click to view)

Answer 4

You can just use dirname function to get what you want:
$path = dirname('/subfolder/page.html'); // returns '/subfolder'
$path = dirname('/subfolder1/subfolder2/page.html'); // returns '/subfolder1'
$path = dirname('page.html'); // returns '.'
EDIT: Regex based solution:
$path = preg_replace('#^(/[^/]*).*$#', '$1', '/subfolder/page.html' )