Generate Slugs from Strings with PHP
In these days of Web 2.0, no site can survive for long without pretty, mod_rewrite-modified permanent links. Everyone uses it. If you look at the URL for this post, for example, it is timjoh.com/generate-slugs-from-strings-with-php. As you might have guessed, I never typed that hyphenated string–WordPress did it all for me. If your PHP script is fed a string that you want a similar slug from, you can use this handy one-liner, with $string being the string that you want to slug.
1 | $slug = str_replace( ' ', '-', preg_replace( '/[^a-z0-9- ]/', '', strtolower( $string ) ) ); |
Or you could use the neater version:
1 2 3 | $slug = strtolower( $string ); // lower-case the string $slug = preg_replace( '/[^a-z0-9- ]/', '', $slug ); // remove all non-alphanumeric characters except for spaces and hyphens $slug = str_replace( ' ', '-', $slug ); // substitute the spaces with hyphens |
This turns the string I'm an U_G_L_Y string! into the slug im-an-ugly-string. Note that it is often useful to shorten the slug; no-one wants a metre-wide URL. It is also important to check so that the slug doesn’t already exist. We can add to the code a loop that appends an ID number to the slug in case it already exists, making it unique.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 | $slug = strtolower( $string ); // lower-case the string $slug = preg_replace( '/[^a-z0-9- ]/', '', $slug ); // remove all non-alphanumeric characters except for spaces and hyphens $slug = str_replace( ' ', '-', $slug ); // substitute the spaces with hyphens $i = ''; // start with no appended value while ( slugExists( $slug . $i ) ) { // if the slug already exists.. $i++; // increment the appended value # it is bad practice to increment a string # but in this case, it simplifies the code } $slug .= $i; // append the value to the real slug function slugExists( $slug ) { # this is just an example function; # the real function depends on the layout of your script $query = sprintf( 'SELECT post_id FROM posts WHERE post_slug = \'%s\'', // write the MySQL query mysql_real_escape_string( $slug ) // escape the string correctly (make sure that magic_quotes_gpc is turned off) ); $result = mysql_query( $query ); // assuming that we are connected to MySQL if ( mysql_num_rows( $result ) ) { // if a post with this slug was found.. return TRUE; // ..this slug exists } else { // if not.. return FALSE; // ..this slug does not exist } } |
Now you can slug whatever you want, without fearing collisions. This means that you can even use the slug column as an ID instead of post_id in this example.
Använder FireStats
I believe you wanted
$slug = str_replace( ‘ ‘, ‘-’, $slug ); // substitute the spaces with hyphens
for line 3, you had a period in the place of a comma.
Comment by Joe — June 25, 2007 @ 2:10 am
Joe: Of course you’re right. It’s fixed now–thank you.
Comment by Tim — June 25, 2007 @ 12:22 pm
[...] Generate Slugs from Strings with PHP — Timblog If your PHP script is fed a string that you want a similar slug from, you can use this handy one-liner, with $string being the string that you want to slug. (tags: php utils) [...]
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