How do you include a webpage title as part of a webpage URL?

Question

What is a good complete Regex or some other process that would take "How do you change a title to be part of the url like Stackoverflow?" and turn it into "how-do-you-change-a-title-to-be-part-of-the-url-like-stackoverflow" that is used in the smart urls?

The dev environment is I am using is Rails but if there are some other platform specific solutions (.net, php, django), I would love to see those too. I am sure I (or another reader) will come across the same problem on a different platform down the line.

-- edit --

I am using custom routes, I mainly want to know how to alter the string to all special chars are removed, it's all lowercase, and all whitespace is replaced.

Answer 1

You will want to setup a custom route to point the url to the controller that will handle it. Since you are using Rails, here is an introduction in using their routing engine.

Edit

Sorry, I misunderstood your question. In Ruby, you will need a regex like you already know and here is the regex to use:

def permalink_for(str)
    str.gsub(/[^\w\/]|[!\(\)\.]+/, ' ').strip.downcase.gsub(/\ +/, '-')
end

Answer 2

On my LAMP sites I use the mod_rewrite function in .htaccess

Read more here: http://httpd.apache.org/docs/1.3/mod/mod_rewrite.html

Answer 3

I am not familiar with Rails, but the following is (untested) PHP code. You can probably translate this very quickly to Rails if you find it useful.

$sURL = "This is a title to convert to URL-format. It has 1 number in it!";
// lower-case
$sURL = strtolower($sURL);
// replace all non-word characters with spaces
$sURL = preg_replace("/\W+/", " ", $sURL);
// remove trailing spaces (so we won't end with a separator)
$sURL = trim($sURL);
// replace spaces with separators (hyphen)
$sURL = str_replace(" ", "-", $sURL);
echo $sURL;
// outputs: this-is-a-title-to-convert-to-url-format-it-has-1-number-in-it

Hope this helps.

Answer 4

I don't much about Ruby or Rails, but in Perl, this is what I would do:

my $title = "How do you change a title to be part of the url like Stackoverflow?";

my $url = lc $title;   # Change to lower case and copy to URL.
$url =~ s/^\s+//g;     # Remove leading spaces.
$url =~ s/\s+$//g;     # Remove trailing spaces.
$url =~ s/\s+/\-/g;    # Change one or more spaces to single hyphen.
$url =~ s/[^\w\-]//g;  # Remove any non-word characters.

print "$title\n$url\n";

I just did a quick test and it seems to work. Hopefully this is relatively easy to translate to Ruby.

Answer 5

Assuming that your model class has a title attribute, you can simply override the to_param method within the model, like this:

def to_param
  title.downcase.gsub(/ /, '-')
end

This Railscast episode has all the details. You can also ensure that the title only contains valid characters using this:

validates_format_of :title, :with => /^[a-z0-9-]+$/,
                    :message => 'can only contain letters, numbers and hyphens'

Answer 6

What about funny characters? What are you going to do about those? Umlauts? Punctuation? These need to be considered. Basically, I would use a white-list approach, as opposed to the black-list approaches above: Describe which characters you will allow, which characters you will convert (to what?) and then change the rest to something meaningfull (""). I doubt you can do this in one regex... Why not just loop through the characters?

Answer 7

Brian's code, in Ruby:

title.downcase.strip.gsub(/\ /, '-').gsub(/[^\w\-]/, '')

downcase turns the string to lowercase, strip removes leading and trailing whitespace, the first gsub call globally substitutes spaces with dashes, and the second removes everything that isn't a letter or a dash.

Answer 8

Here's how we do it. Note that there are probably more edge conditions than you realize at first glance.

This is the second version, unrolled for 5x more performance (and yes, I benchmarked it). I figured I'd optimize it because this function can be called hundreds of times per page.

if (String.IsNullOrEmpty(title)) return "";

// to lowercase, trim extra spaces
title = title.ToLower().Trim();

var len = title.Length;
var sb = new StringBuilder(len);
bool prevdash = false;
char c;

for (int i = 0; i < title.Length; i++)
{
    c = title[i];
    if (c == ' ' || c == ',' || c == '.' || c == '/' || c == '\\' || c == '-')
    {
        if (!prevdash)
        {
            sb.Append('-');
            prevdash = true;
        }
    }
    else if ((c >= 'a' && c <= 'z') || (c >= '0' && c <= '9'))
    {
        sb.Append(c);
        prevdash = false;
    }
    if (i == 80) break;
}

title = sb.ToString();
// remove trailing dash, if there is one
if (title.EndsWith("-"))
    title = title.Substring(0, title.Length - 1);
return title;

To see the previous version of the code this replaced (but is functionally equivalent to, and 5x faster), view revision history of this post (click the date link).

Answer 9

I'd add to the answers here that this is commonly known as a URL 'slug' if you want to google the term.

Answer 10

There is a small Rails plugin called PermalinkFu, that does this.

The escape method does the transformation into a string that is suitable for a url. Have a look at the code, that method is quite simple.

To remove non-ascii chars it uses the iconv lib to translate to 'ascii//ignore//translit' from 'utf-8'. Spaces are then turned into dashes, everything is downcased etc.

Answer 11

T-SQL implementation, adapted from dbo.UrlEncode:

CREATE FUNCTION dbo.Slug(@string varchar(1024))
RETURNS varchar(3072)
AS
BEGIN
 DECLARE @count int, @c char(1), @i int, @slug varchar(3072)

 SET @string = replace(lower(ltrim(rtrim(@string))),' ','-')

 SET @count = Len(@string)
 SET @i = 1
 SET @slug = ''

 WHILE (@i <= @count)
 BEGIN
  SET @c = substring(@string, @i, 1)

  IF @c LIKE '[a-z0-9--]'
   SET @slug = @slug + @c

  SET @i = @i +1
 END

 RETURN @slug
END

Answer 12

If you are using Rails edge, you can rely on Inflector.parametrize - here's the example from the documentation:

  class Person
    def to_param
      "#{id}-#{name.parameterize}"
    end
  end

  @person = Person.find(1)
  # => #<Person id: 1, name: "Donald E. Knuth">

  <%= link_to(@person.name, person_path(@person)) %>
  # => <a href="/person/1-donald-e-knuth">Donald E. Knuth</a>

Also if you need to handle more exotic characters such as accents (éphémère) in previous version of Rails, you can use a mixture of PermalinkFu and DiacriticsFu:

DiacriticsFu::escape("éphémère")
=> "ephemere"

DiacriticsFu::escape("räksmörgås")
=> "raksmorgas"

cheers!

Thibaut

--

http://blog.logeek.fr

Answer 13

no, no, no. you are all so very wrong. Except for the diacritics-fu stuff, you're getting there, but what about asian characters (shame on ruby developers for not considering their nihonjin brethren)

firefox and safari both display non-ascii characters in the url, and frankly they look great. It is nice to support links like 'http://somewhere.com/news/read/お前たちはアホじゃないかい'

so here's some PHP code that'll do it, but I just wrote it, and haven't stress tested it.

<?php

function slug($str)
{
  $args = func_get_args();
  array_filter($args);  //remove blanks
  $slug = mb_strtolower(implode('-', $args));

  $real_slug = '';
  $hyphen = '';
  foreach(SU::mb_str_split($slug) as $c)
  {
    if (strlen($c) > 1 && mb_strlen($c)===1)
    {
      $real_slug .= $hyphen . $c;
      $hyphen = '';
    }
    else
    {
      switch($c)
      {
        case '&':
          $hyphen = $real_slug ? '-and-' : '';
          break;
        case 'a': case 'b': case 'c': case 'd': case 'e': case 'f': case 'g': case 'h': case 'i': case 'j': case 'k': case 'l': case 'm':
        case 'n': case 'o': case 'p': case 'q': case 'r': case 's': case 't': case 'u': case 'v': case 'w': case 'x': case 'y': case 'z':
        case 'A': case 'B': case 'C': case 'D': case 'E': case 'F': case 'G': case 'H': case 'I': case 'J': case 'K': case 'L': case 'M':
        case 'N': case 'O': case 'P': case 'Q': case 'R': case 'S': case 'T': case 'U': case 'V': case 'W': case 'X': case 'Y': case 'Z':
        case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9':
          $real_slug .= $hyphen . $c;
          $hyphen = '';
          break;
        default:
          $hyphen = $hyphen ? $hyphen : ($real_slug ? '-' : '');
      }
    }
  }

  return $real_slug;
}

Example:

$str = "~!@#$%^&*()_+-=[]\{}|;':\",./<>?\n\r\t\x07\x00\x04 コリン ~!@#$%^&*()_+-=[]\{}|;':\",./<>?\n\r\t\x07\x00\x04 トーマス ~!@#$%^&*()_+-=[]\{}|;':\",./<>?\n\r\t\x07\x00\x04 アーノルド ~!@#$%^&*()_+-=[]\{}|;':\",./<>?\n\r\t\x07\x00\x04";
echo slug($str);

Outputs: コリン-and-トーマス-and-アーノルド

the '-and-' is because &'s get changed to '-and-'.