如何截断动态长度为 url slug 的字符串？

Question

On my slug column I set the limit is varchar = 100 and the values will store like this

how-do-i-truncate-a-string-with-dynamic-length-url-slug

I want the slug will be a unique key so I update the slug value with last auto increment id and new slug value is:

how-do-i-truncate-a-string-with-dynamic-length-url-slug-10

So here the last auto increment will be a big number at the end..

preg_replace('/\s+?(\S+)?$/', '', substr($slugwithautoincrement, 0, 101));

With this preg_replace it will remove my auto increment number

Question:

How do I truncate the value fix to 100 characters without remove the last auto increment number?

So result should be:

how-do-i-truncate-a-string-with-[....remove from here...]10

Answer 1

Truncate first and then append the auto increment value.

Or do something like this:

$maxlength = 30;
$number = 1234567;
$string = "how-do-i-truncate-a-string-with-dynamic-length-url-slug";
$slug = substr($string, 0, $maxlength - strlen($number) - 1)."-".$number;

Answer 2

Here's one way to do it:

$slug = "how-do-i-truncate-a-string-with-dynamic-length-url-slug-10"
$maxlen = 100;
if (strlen($slug) > $maxlen) {
    $idlen = strlen($slug) - strrpos($slug, '-'); // how long is the "-10" part?
    $id = substr($slug, -$idlen);
    $slug = substr($slug, 0, $maxlen - $idlen).$id;
}
echo $slug;

This code can possibly end up with two hyphens before the id if $maxlen happens to have specific values. That should not be a problem though.

Answer 3

If you can't truncate before appending the auto increment value:

$slug = explode('-', $slug);

$value = array_pop($slug);

$slug = substr(implode('-', $slug), 0, 99 - strlen($value)) . '-' . $value;