Rails: How to downcase non-English string?

Question

How could I downcase a non-English string in Ruby on Rails 3 ?

str = "Привет"    # Russian 
puts str[0].ord   # => 1055
str.downcase!
puts str[0].ord   # => 1055 (Should be 1087)

I want it to work in Ruby 1.8.7 as well as Ruby 1.9.2.

Currently, I'm interested in the Russian language, but I may want to use other languages in future, so I'm looking for a general solution. — Misha Moroshko, Sep 11 '11 at 12:11

score 97 · Accepted Answer · answered Sep 11 '11 at 12:36

97

str = "Привет"
str.mb_chars.downcase.to_s
#=> "привет"

answered Sep 11 '11 at 12:36

fl00r

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5

Without rails you need an aditional `require 'active_support/core_ext'` to avoid an _undefined method_-error – knut Jul 26 '12 at 07:38
3

awesome why they didn't fix it in ruby 2.0 :( – Egor Malkevich Aug 22 '13 at 14:36
`mb_chars` also works with `capitalize` and `upcase`. Great solution! We also can call `'Привет'.mb_chars.downcase.wrapped_string` – Stepan Zakharov Jun 07 '16 at 06:33
4

In Ruby 2.4 it finally works as expected: `"Привет".downcase #=> "привет"` – kxmh42 Sep 01 '16 at 19:05

score 7 · Answer 2 · edited Apr 14 '15 at 16:53

7

Why not to use gem unicode_utils. This gem will not force downcase to work, however you can use:

UnicodeUtils.downcase('Привет') #=> 'привет'

edited Apr 14 '15 at 16:53

Nakilon

34,866
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answered Mar 09 '14 at 13:37

Developer

983
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12

score 6 · Answer 3 · answered Dec 10 '16 at 12:53

If you want to use it easy like this:

> "Привет".downcase
=> "привет"

you have to put into initializers folder file string.rb

require 'unicode'

class String
  def downcase
    Unicode::downcase(self)
  end
  def downcase!
    self.replace downcase
  end
  def upcase
    Unicode::upcase(self)
  end
  def upcase!
    self.replace upcase
  end
  def capitalize
    Unicode::capitalize(self)
  end
  def capitalize!
    self.replace capitalize
  end
end

score 2 · Answer 4 · answered Sep 18 '17 at 14:57

2

Since Ruby 2.4 there is a built in full Unicode case mapping. Source: https://stackoverflow.com/a/38016153/888294. See Ruby 2.4.0 documentation for details: https://ruby-doc.org/core-2.4.0/String.html#method-i-downcase

answered Sep 18 '17 at 14:57

mmichaa

760
6
11

score 1 · Answer 5 · answered Jul 08 '19 at 14:20

A nice and easy solution in rails is to add string.rb into initializers folder, then in this file you can override String using mb_chars, now downcase support accents and letters like Ñ

class String
  def downcase
    self.mb_chars.downcase.to_s
  end

  def capitalize
    self.mb_chars.capitalize.to_s
  end

  def upcase
    self.mb_chars.upcase.to_s
  end

  def titleize
    self.mb_chars.titleize.to_s
  end
end

Rails: How to downcase non-English string?

5 Answers5