PHP function to make slug (URL string)

Question

function gen_slug($str){
    # special accents
    $a = array('À','Á','Â','Ã','Ä','Å','Æ','Ç','È','É','Ê','Ë','Ì','Í','Î','Ï','Ð','Ñ','Ò','Ó','Ô','Õ','Ö','Ø','Ù','Ú','Û','Ü','Ý','ß','à','á','â','ã','ä','å','æ','ç','è','é','ê','ë','ì','í','î','ï','ñ','ò','ó','ô','õ','ö','ø','ù','ú','û','ü','ý','ÿ','A','a','A','a','A','a','C','c','C','c','C','c','C','c','D','d','Ð','d','E','e','E','e','E','e','E','e','E','e','G','g','G','g','G','g','G','g','H','h','H','h','I','i','I','i','I','i','I','i','I','i','?','?','J','j','K','k','L','l','L','l','L','l','?','?','L','l','N','n','N','n','N','n','?','O','o','O','o','O','o','Œ','œ','R','r','R','r','R','r','S','s','S','s','S','s','Š','š','T','t','T','t','T','t','U','u','U','u','U','u','U','u','U','u','U','u','W','w','Y','y','Ÿ','Z','z','Z','z','Ž','ž','?','ƒ','O','o','U','u','A','a','I','i','O','o','U','u','U','u','U','u','U','u','U','u','?','?','?','?','?','?');
    $b = array('A','A','A','A','A','A','AE','C','E','E','E','E','I','I','I','I','D','N','O','O','O','O','O','O','U','U','U','U','Y','s','a','a','a','a','a','a','ae','c','e','e','e','e','i','i','i','i','n','o','o','o','o','o','o','u','u','u','u','y','y','A','a','A','a','A','a','C','c','C','c','C','c','C','c','D','d','D','d','E','e','E','e','E','e','E','e','E','e','G','g','G','g','G','g','G','g','H','h','H','h','I','i','I','i','I','i','I','i','I','i','IJ','ij','J','j','K','k','L','l','L','l','L','l','L','l','l','l','N','n','N','n','N','n','n','O','o','O','o','O','o','OE','oe','R','r','R','r','R','r','S','s','S','s','S','s','S','s','T','t','T','t','T','t','U','u','U','u','U','u','U','u','U','u','U','u','W','w','Y','y','Y','Z','z','Z','z','Z','z','s','f','O','o','U','u','A','a','I','i','O','o','U','u','U','u','U','u','U','u','U','u','A','a','AE','ae','O','o');
    return strtolower(preg_replace(array('/[^a-zA-Z0-9 -]/','/[ -]+/','/^-|-$/'),array('','-',''),str_replace($a,$b,$str)));
}

Works great, but I've found some cases in which it fails:

gen_slug('andrés') returns andras instead of andres

Why? Any ideas on the preg_replace parameters?

Answer 1

Since gTLDs and IDNs are becoming more and more used I cannot see why URL shouldn't contain Andrés.

Just rawurlencode $URL you want instead. Most browsers show UTF-8 characters in URLs (not some ancient IE6 maybe) and bit.ly / goo.gl can be used to make it short in cases like Russian and Arabic if need may be for ad purposes or just write them in ads like user would write them on browser URL.

Only difference is spaces " " it might be good idea to replace them with "-" and "/" if you don't want to allow those.

<?php
function slugify($url)
{
    $url = trim($url);

    $url = str_replace(" ","-",$url);
    $url = str_replace("/","-slash-",$url);
    $url = rawurlencode($url);
}
?>

Url as encoded http://www.hurtta.com/RU/%D0%9F%D1%80%D0%BE%D0%B4%D1%83%D0%BA%D1%82%D1%8B/

Url as written http://www.hurtta.com/RU/Продукты/

Answer 2

I wrote this based on Maerlyn's response. This function will work regardless of the character encoding on the page. It also won't turn single quotes in to dashes :)

function slugify ($string) {
    $string = utf8_encode($string);
    $string = iconv('UTF-8', 'ASCII//TRANSLIT', $string);   
    $string = preg_replace('/[^a-z0-9- ]/i', '', $string);
    $string = str_replace(' ', '-', $string);
    $string = trim($string, '-');
    $string = strtolower($string);

    if (empty($string)) {
        return 'n-a';
    }

    return $string;
}

Answer 3

I am using:

function slugify($text)
{ 
    $text = iconv('utf-8', 'us-ascii//TRANSLIT', $text);
    return strtolower(preg_replace('/[^A-Za-z0-9-]+/', '-', $text));
}

Only fallback is that Cyrillic characters will not be converted, and I am searching now for solution that is not long str_replace for every single Cyrillic character.

Answer 4

Note: I have taken this from wordpress and it works!!

Use it like this:

echo sanitize('testing this link');

Code

//taken from wordpress
function utf8_uri_encode( $utf8_string, $length = 0 ) {
    $unicode = '';
    $values = array();
    $num_octets = 1;
    $unicode_length = 0;

    $string_length = strlen( $utf8_string );
    for ($i = 0; $i < $string_length; $i++ ) {

        $value = ord( $utf8_string[ $i ] );

        if ( $value < 128 ) {
            if ( $length && ( $unicode_length >= $length ) )
                break;
            $unicode .= chr($value);
            $unicode_length++;
        } else {
            if ( count( $values ) == 0 ) $num_octets = ( $value < 224 ) ? 2 : 3;

            $values[] = $value;

            if ( $length && ( $unicode_length + ($num_octets * 3) ) > $length )
                break;
            if ( count( $values ) == $num_octets ) {
                if ($num_octets == 3) {
                    $unicode .= '%' . dechex($values[0]) . '%' . dechex($values[1]) . '%' . dechex($values[2]);
                    $unicode_length += 9;
                } else {
                    $unicode .= '%' . dechex($values[0]) . '%' . dechex($values[1]);
                    $unicode_length += 6;
                }

                $values = array();
                $num_octets = 1;
            }
        }
    }

    return $unicode;
}

//taken from wordpress
function seems_utf8($str) {
    $length = strlen($str);
    for ($i=0; $i < $length; $i++) {
        $c = ord($str[$i]);
        if ($c < 0x80) $n = 0; # 0bbbbbbb
        elseif (($c & 0xE0) == 0xC0) $n=1; # 110bbbbb
        elseif (($c & 0xF0) == 0xE0) $n=2; # 1110bbbb
        elseif (($c & 0xF8) == 0xF0) $n=3; # 11110bbb
        elseif (($c & 0xFC) == 0xF8) $n=4; # 111110bb
        elseif (($c & 0xFE) == 0xFC) $n=5; # 1111110b
        else return false; # Does not match any model
        for ($j=0; $j<$n; $j++) { # n bytes matching 10bbbbbb follow ?
            if ((++$i == $length) || ((ord($str[$i]) & 0xC0) != 0x80))
                return false;
        }
    }
    return true;
}

//function sanitize_title_with_dashes taken from wordpress
function sanitize($title) {
    $title = strip_tags($title);
    // Preserve escaped octets.
    $title = preg_replace('|%([a-fA-F0-9][a-fA-F0-9])|', '---$1---', $title);
    // Remove percent signs that are not part of an octet.
    $title = str_replace('%', '', $title);
    // Restore octets.
    $title = preg_replace('|---([a-fA-F0-9][a-fA-F0-9])---|', '%$1', $title);

    if (seems_utf8($title)) {
        if (function_exists('mb_strtolower')) {
            $title = mb_strtolower($title, 'UTF-8');
        }
        $title = utf8_uri_encode($title, 200);
    }

    $title = strtolower($title);
    $title = preg_replace('/&.+?;/', '', $title); // kill entities
    $title = str_replace('.', '-', $title);
    $title = preg_replace('/[^%a-z0-9 _-]/', '', $title);
    $title = preg_replace('/\s+/', '-', $title);
    $title = preg_replace('|-+|', '-', $title);
    $title = trim($title, '-');

    return $title;
}

Answer 5

on my localhost everything was ok, but on server it helped me "set_locale" and "utf-8" at "mb_strtolower".

<?
setlocale( LC_ALL, "en_US.UTF8" );
function slug( $string )
{
    $string = iconv( "utf-8", "us-ascii//translit//ignore", $string ); // transliterate
    $string = str_replace( "'", "", $string );
    $string = preg_replace( "~[^\pL\d]+~u", "-", $string ); // replace non letter or non digits by "-"
    $string = preg_replace( "~[^-\w]+~", "", $string ); // remove unwanted characters
    $string = preg_replace( "~-+~", "-", $string ); // remove duplicate "-"
    $string = trim( $string, "-" ); // trim "-"
    $string = trim( $string ); // trim
    $string = mb_strtolower( $string, "utf-8" ); // lowercase
    $string = urlencode( $string ); // safe
    return $string;
};
?>

Answer 6

If you have intl extension installed, you can use transliterator_transliterate function to create a slug easily.

You can replace spaces with dashes later to make it more like a slug.

<?php
$string = "andrés";
$string = transliterator_transliterate("Any-Latin; NFD; [:Nonspacing Mark:] Remove; NFC; [:Punctuation:] Remove; Lower();", $string);
echo $string;
?>