How to append variables to a url which already has variables?

Question

Hi all,

So, the situation I'm currently in is a wee bit complicated (for me that is), but I'm gonna give it a try.

I would like to run to a snippet of HTML and extract all the links referring to my own domain. Next I want to append these URL's with a predefined string of GET vars. For example, I want to append '?var1=2&var2=4' to 'http://www.domain.com/page/' thus creating 'http://www.domain.com/page/?var1=2&var2=4'.

The method I'm currently applying is a simple preg_replace function (PHP), but here is when it gets interesting. How do i create valid appended url's when they already have some GET vars at the end? For example, it could create a url like this: 'http://www.domain.com/page/?already=here&another=one?var1=2&var2=4' thus breaking the GET data.

So to conclude, what I'm looking for is a reg exp which can cope with these scenarios, create my extended url and write it back to the HTML snippet.

This is what I have so far:

$sHTML = preg_replace("'href=\"($domainURL.*?[\/$])\"'", 'href="\1' . $appendedTags . '"', $sHTML);

Thanks in advance

Answer 1

Regex are not the solution, as somebody said:

Some people, when confronted with a problem, think "I know, I'll use regular expressions." Now they have two problems.

But nevermind that, what I would use, is parse_url, and then append my var1=1&var2=2 to the result query string. Something along the lines of:

$broken = parse_url($url);
$broken['query'] .= '&var1=1&var2=2';
if (strpos($broken,'&')==0) $broken['query'] = substr($broken['query'],1);
return $broken['scheme'].'://'.$broken['host'].$broken['path'].
  '?'.$broken['query'].'#'.$broken['fragment'];

If you don't want your variable to appear twice, use also parse_str to break apart the query string.

Answer 2

In addition to what Elazar Leibovich suggested, I'd parse the query string with parse_str(), modify the resulting array to my needs and then use http_build_query() to rebuild the query string. This way you won't have any duplicates within your query string and you don't have to bother yourself with url-encoding your query-parts.

The complete example would then look like (augmenting Elazar Leibovich code):

$broken = parse_url($url);
$query = parse_str($broken['query']);
$query['var1'] = 1;
$query['var2'] = 2;
$broken['query'] = http_build_query($query);
return $broken['scheme'] . '://' . $broken['host'] . $broken['path'] .
  '?' . $broken['query'] . '#' . $broken['fragment'];

Answer 3

Also the parse_str wont return any values as shown in the answer rather it takes an array as a param:

$array = array();    
parse_str($url,$array);
// $array will contain the ["scheme"] ["host"] etc

just a side note ;)

-- G