preg_replace to add own website before every hyperlink

Question

For a project, I need to fetch a websites content and alter the HTML code. Every link on that website has to be replaced with my own aswell. I used str_replace until I realized that links sometimes have classes assigned to them.

I've tried the preg_replace function to add my own website before every href link that is also between <a> </a> tags. It shouldn't matter whether or not the fetched website in $content contains href="" or href=''.

$content = preg_replace('~(<a\b[^>]*\shref=")([^"]*)(")~igs', '\1http://website.com/fetch.php?url=\2\3', $content);

This does not work and I can't find the error. It should behave as follows:

<a class="link" href="http://google.com">Google</a>

should turn into

<a class="link" href="http://website.com/fetch.php?url=http://google.com">Google</a>

Can someone help me find the error? Thank you in advance.

Don't use a regex, you will run into similar issues you found with `str_replace`. Use a parser. Also if not using a function you don't need `preg_replace_callback`, `preg_replace` will replace.... Also there is no `g` modifier in PHP. The functions are global. — chris85, Oct 30 '16 at 00:22
It's preferable to use `$1`, `$2`, etc. in the replacement string. — Barmar, Oct 30 '16 at 00:22
Possible duplicate of [How do you parse and process HTML/XML in PHP?](http://stackoverflow.com/questions/3577641/how-do-you-parse-and-process-html-xml-in-php) — chris85, Oct 30 '16 at 00:22
When you use `preg_replace_callback`, the second argument must be a function, not a string. Did you mean to use `preg_replace`? — Barmar, Oct 30 '16 at 00:24
PHP doesn't allow the `g` modifier, because `preg_replace` always replaces all matches. — Barmar, Oct 30 '16 at 00:25
When I remove the `g` modifier your code works. Didn't you notice the error message from that? — Barmar, Oct 30 '16 at 00:26
Your code won't work if the href attribute uses single quotes instead of double quotes. — Barmar, Oct 30 '16 at 00:27
@Barmar even with your answers, it just seems to replace every `href` that comes right after the `` tag. This is however a big step forward because previously it would replace nothing at all. — Mikusch, Oct 30 '16 at 01:03
`$content = preg_replace('~(]*\shref=")([^"]*)(")~is', '\1http://website.com/fetch.php?url=\2\3', $content);` — Mikusch, Oct 30 '16 at 01:04
What do you mean? I tried it with the string above and it produced the desired result. — Barmar, Oct 30 '16 at 01:06
But as the linked question suggests, it's better to use a DOM parser instead of regexp to process HTML. — Barmar, Oct 30 '16 at 01:07
You should use `urlecode()` to encode the original URL when you put it into the parameter section. This will require going back to `preg_replace_callback()`. — Barmar, Oct 30 '16 at 01:08

score 0 · Answer 1 · answered Nov 03 '16 at 03:48

0

Don't half-arse a regex that will miss plenty of cases. Just read each document into a DOM tree (give this html5 DOM parser a go), and use XPath to get all links with href attributes, and update them, then save the result.

answered Nov 03 '16 at 03:48

Walf

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score 0 · Answer 2 · answered Nov 03 '16 at 04:14

just use simplexml and preg_replace

        <?php

            $string= '<a class="link" href="http://google.com">Google</a>';

            $a = new SimpleXMLElement('<a class="link" href="http://google.com">Google</a>');

            $newurl="http://website.com/fetch.php?url=".urlencode($a['href']);

            $pattern = "/(?<=href=(\"|'))[^\"']+(?=(\"|'))/";

            $body = preg_replace($pattern,$newurl,$string);

            echo $body;


         ?>

OUTPUT:

<a class="link" href="http://website.com/fetch.php?url=http%3A%2F%2Fgoogle.com">Google</a>

preg_replace to add own website before every hyperlink

2 Answers2