How can I create a SEO friendly dash-delimited url

Question

Take a string such as:

In C#: How do I add "Quotes" around string in a comma delimited list of strings?

and convert it to:

in-c-how-do-i-add-quotes-around-string-in-a-comma-delimited-list-of-strings

Requirements:

• Separate each word by a dash and remove all punctuation (taking into account not all words are separated by spaces.)
• Function takes in a max length, and gets all tokens below that max length. Example: ToSeoFriendly("hello world hello world", 14) returns "hello-world"
• All words are converted to lower case.

On a separate note, should there be a minimum length?

Answer 1

Here is my solution in C#

private string ToSeoFriendly(string title, int maxLength) {
    var match = Regex.Match(title.ToLower(), "[\\w]+");
    StringBuilder result = new StringBuilder("");
    bool maxLengthHit = false;
    while (match.Success && !maxLengthHit) {
        if (result.Length + match.Value.Length <= maxLength) {
            result.Append(match.Value + "-");
        } else {
            maxLengthHit = true;
            // Handle a situation where there is only one word and it is greater than the max length.
            if (result.Length == 0) result.Append(match.Value.Substring(0, maxLength));
        }
        match = match.NextMatch();
    }
    // Remove trailing '-'
    if (result[result.Length - 1] == '-') result.Remove(result.Length - 1, 1);
    return result.ToString();
}

Answer 2

Here's a solution for php:

function make_uri($input, $max_length) {
  if (function_exists('iconv')) {  
    $input = @iconv('UTF-8', 'ASCII//TRANSLIT', $input);  
  }

  $lower = strtolower($input);


  $without_special = preg_replace_all('/[^a-z0-9 ]/', '', $input);
  $tokens = preg_split('/ +/', $without_special);

  $result = '';

  for ($tokens as $token) {
    if (strlen($result.'-'.$token) > $max_length+1) {
      break;
    }

    $result .= '-'.$token;       
  }

  return substr($result, 1);
}

usage:

echo make_uri('In C#: How do I add "Quotes" around string in a ...', 500);

Unless you need the uris to be typable, they don't need to be small. But you should specify a maximum so that the urls work well with proxies etc.

Answer 3

This is close to how Stack Overflow generates slugs:

public static string GenerateSlug(string title)
{
    string slug = title.ToLower();
    if (slug.Length > 81)
      slug = slug.Substring(0, 81);
    slug = Regex.Replace(slug, @"[^a-z0-9\-_\./\\ ]+", "");
    slug = Regex.Replace(slug, @"[^a-z0-9]+", "-");

    if (slug[slug.Length - 1] == '-')
      slug = slug.Remove(slug.Length - 1, 1);
    return slug;
}

Answer 4

A slightly cleaner way of doing this in PHP at least is:

function CleanForUrl($urlPart, $maxLength = null) {
    $url = strtolower(preg_replace(array('/[^a-z0-9\- ]/i', '/[ \-]+/'), array('', '-'), trim($urlPart)));
    if ($maxLength) $url = substr($url, 0, $maxLength);
    return $url;
}

Might as well do the trim() at the start so there is less to process later and the full replacement is done with in the preg_replace().

Thxs to cg for coming up with most of this: What is the best way to clean a string for placement in a URL, like the question name on SO?

Answer 5

I would follow these steps:

1. convert string to lower case
2. replace unwanted characters by hyphens
3. replace multiple hyphens by one hyphen (not necessary as the preg_replace() function call already prevents multiple hyphens)
4. remove hypens at the begin and end if necessary
5. trim if needed from the last hyphen before position x to the end

So, all together in a function (PHP):

function generateUrlSlug($string, $maxlen=0)
{
    $string = trim(preg_replace('/[^a-z0-9]+/', '-', strtolower($string)), '-');
    if ($maxlen && strlen($string) > $maxlen) {
        $string = substr($string, 0, $maxlen);
        $pos = strrpos($string, '-');
        if ($pos > 0) {
            $string = substr($string, 0, $pos);
        }
    }
    return $string;
}

Answer 6

Another season, another reason, for choosing Ruby :)

def seo_friendly(str)
  str.strip.downcase.gsub /\W+/, '-'
end

That's all.