How do I replace accented Latin characters in Ruby?
Ruby on-RailsRubyActiverecordUnicodeUtf 8Ruby on-Rails Problem Overview
I have an ActiveRecord
model, Foo
, which has a name
field. I'd like users to be able to search by name, but I'd like the search to ignore case and any accents. Thus, I'm also storing a canonical_name
field against which to search:
class Foo
validates_presence_of :name
before_validate :set_canonical_name
private
def set_canonical_name
self.canonical_name ||= canonicalize(self.name) if self.name
end
def canonicalize(x)
x.downcase. # something here
end
end
I need to fill in the "something here" to replace the accented characters. Is there anything better than
x.downcase.gsub(/[àáâãäå]/,'a').gsub(/æ/,'ae').gsub(/ç/, 'c').gsub(/[èéêë]/,'e')....
And, for that matter, since I'm not on Ruby 1.9, I can't put those Unicode literals in my code. The actual regular expressions will look much uglier.
Ruby on-Rails Solutions
Solution 1 - Ruby on-Rails
ActiveSupport::Inflector.transliterate
(requires Rails 2.2.1+ and Ruby 1.9 or 1.8.7)
example:
>> ActiveSupport::Inflector.transliterate("àáâãäå").to_s => "aaaaaa"
Solution 2 - Ruby on-Rails
Rails has already a builtin for normalizing, you just have to use this to normalize your string to form KD and then remove the other chars (i.e. accent marks) like this:
>> "àáâãäå".mb_chars.normalize(:kd).gsub(/[^\x00-\x7F]/n,'').downcase.to_s
=> "aaaaaa"
Solution 3 - Ruby on-Rails
Better yet is to use I18n:
1.9.3-p392 :001 > require "i18n"
=> false
1.9.3-p392 :002 > I18n.transliterate("Olá Mundo!")
=> "Ola Mundo!"
Solution 4 - Ruby on-Rails
I have tried a lot of this approaches but they were not achieving one or several of these requirements:
- Respect spaces
- Respect 'ñ' character
- Respect case (I know is not a requirement for the original question but is not difficult to move an string to lowcase)
Has been this:
# coding: utf-8
string.tr(
"ÀÁÂÃÄÅàáâãäåĀāĂ㥹ÇçĆćĈĉĊċČčÐðĎďĐđÈÉÊËèéêëĒēĔĕĖėĘęĚěĜĝĞğĠġĢģĤĥĦħÌÍÎÏìíîïĨĩĪīĬĭĮįİıĴĵĶķĸĹĺĻļĽľĿŀŁłÑñŃńŅņŇňʼnŊŋÒÓÔÕÖØòóôõöøŌōŎŏŐőŔŕŖŗŘřŚśŜŝŞşŠšſŢţŤťŦŧÙÚÛÜùúûüŨũŪūŬŭŮůŰűŲųŴŵÝýÿŶŷŸŹźŻżŽž",
"AAAAAAaaaaaaAaAaAaCcCcCcCcCcDdDdDdEEEEeeeeEeEeEeEeEeGgGgGgGgHhHhIIIIiiiiIiIiIiIiIiJjKkkLlLlLlLlLlNnNnNnNnnNnOOOOOOooooooOoOoOoRrRrRrSsSsSsSssTtTtTtUUUUuuuuUuUuUuUuUuUuWwYyyYyYZzZzZz"
)
You have to modify a little bit the character list to respect 'ñ' character but is an easy job.
Solution 5 - Ruby on-Rails
My answer: the String#parameterize method:
"Le cœur de la crémiére".parameterize
=> "le-coeur-de-la-cremiere"
For non-Rails programs:
Install activesupport: gem install activesupport
then:
require 'active_support/inflector'
"a&]'s--3\014\xC2àáâã3D".parameterize
# => "a-s-3-3d"
Solution 6 - Ruby on-Rails
I think that you maybe don't really what to go down that path. If you are developing for a market that has these kind of letters your users probably will think you are a sort of ...pip. Because 'å' isn't even close to 'a' in any meaning to a user. Take a different road and read up about searching in a non-ascii way. This is just one of those cases someone invented unicode and collation.
A very late PS:
http://www.w3.org/International/wiki/Case_folding http://www.w3.org/TR/charmod-norm/#sec-WhyNormalization
Besides that I have no ide way the link to collation go to a msdn page but I leave it there. It should have been http://www.unicode.org/reports/tr10/
Solution 7 - Ruby on-Rails
Decompose the string and remove non-spacing marks from it.
irb -ractive_support/all
> "àáâãäå".mb_chars.normalize(:kd).gsub(/\p{Mn}/, '')
aaaaaa
You may also need this if used in a .rb file.
# coding: utf-8
the normalize(:kd)
part here splits out diacriticals where possible (ex: the "n with tilda" single character is split into an n followed by a combining diacritical tilda character), and the gsub
part then removes all the diacritical characters.
Solution 8 - Ruby on-Rails
This assumes you use Rails.
"anything".parameterize.underscore.humanize.downcase
Given your requirements, this is probably what I'd do... I think it's neat, simple and will stay up to date in future versions of Rails and Ruby.
Update: dgilperez pointed out that parameterize
takes a separator argument, so "anything".parameterize(" ")
(deprecated) or "anything".parameterize(separator: " ")
is shorter and cleaner.
Solution 9 - Ruby on-Rails
Convert the text to normalization form D, remove all codepoints with unicode category non spacing mark (Mn), and convert it back to normalization form C. This will strip all diacritics, and your problem is reduced to a case insensitive search.
See http://www.siao2.com/2005/02/19/376617.aspx and http://www.siao2.com/2007/05/14/2629747.aspx for details.
Solution 10 - Ruby on-Rails
The key is to use two columns in your database: canonical_text
and original_text
. Use original_text
for display and canonical_text
for searches. That way, if a user searches for "Visual Cafe," she sees the "Visual Café" result. If she really wants a different item called "Visual Cafe," it can be saved separately.
To get the canonical_text characters in a Ruby 1.8 source file, do something like this:
register_replacement([0x008A].pack('U'), 'S')
Solution 11 - Ruby on-Rails
You probably want Unicode decomposition ("NFD"). After decomposing the string, just filter out anything not in [A-Za-z]. æ will decompose to "ae", ã to "a~" (approximately - the diacritical will become a separate character) so the filtering leaves a reasonable approximation.
Solution 12 - Ruby on-Rails
iconv:
http://groups.google.com/group/ruby-talk-google/browse_frm/thread/8064dcac15d688ce?
=============
a perl module which i can't understand:
http://www.ahinea.com/en/tech/accented-translate.html
============
brute force (there's a lot of htose critters!:
http://projects.jkraemer.net/acts_as_ferret/wiki#UTF-8support
Solution 13 - Ruby on-Rails
For anyone reading this wanting to strip all non-ascii characters this might be useful, I used the first example successfully.
Solution 14 - Ruby on-Rails
I had problems getting the foo.mb_chars.normalize(:kd).gsub(/[^\x00-\x7F]/n,'').downcase.to_s solution to work. I'm not using Rails and there was some conflict with my activesupport/ruby versions that I couldn't get to the bottom of.
Using the ruby-unf gem seems to be a good substitute:
require 'unf'
foo.to_nfd.gsub(/[^\x00-\x7F]/n,'').downcase
As far as I can tell this does the same thing as .mb_chars.normalize(:kd). Is this correct? Thanks!
Solution 15 - Ruby on-Rails
If you are using PostgreSQL => 9.4 as your DB adapter, maybe you could add in a migration it's "unaccent" extension that I think does what you want, like this:
def self.up
enable_extension "unaccent" # No falla si ya existe
end
In order to test, in the console:
2.3.1 :045 > ActiveRecord::Base.connection.execute("SELECT unaccent('unaccent', 'àáâãäåÁÄ')").first
=> {"unaccent"=>"aaaaaaAA"}
Notice there is case sensitive up to now.
Then, maybe use it in a scope, like:
scope :with_canonical_name, -> (name) {
where("unaccent(foos.name) iLIKE unaccent('#{name}')")
}
The iLIKE operator makes the search case insensitive. There is another approach, using citext data type. Here is a discussion about this two approaches. Notice also that use of PosgreSQL's lower() function is not recommended.
This will save you some DB space, since you will no longer require the cannonical_name field, and perhaps make your model simpler, at the cost of some extra processing in each query, in an amount depending of whether you are using iLIKE or citext, and your dataset.
If you are using MySQL maybe you can use this simple solution, but I have not tested it.
Solution 16 - Ruby on-Rails
lol.. i just tryed this.. and it is working.. iam still not pretty sure why.. but when i use this 4 lines of code:
- str = str.gsub(/[^a-zA-Z0-9 ]/,"")
- str = str.gsub(/[ ]+/," ")
- str = str.gsub(/ /,"-")
- str = str.downcase
it automaticly removes any accent from filenames.. which i was trying to remove(accent from filenames and renaming them than) hope it helped :)