在ruby中将驼峰大小写转换为下划线大小写

Rails' ActiveSupport 使用以下命令向字符串添加下划线:

class String
  def underscore
    self.gsub(/::/, '/').
    gsub(/([A-Z]+)([A-Z][a-z])/,'\1_\2').
    gsub(/([a-z\d])([A-Z])/,'\1_\2').
    tr("-", "_").
    downcase
  end
end

"CamelCase".underscore
=> "camel_case"

你可以用

"CamelCasedName".tableize.singularize

"CamelCasedName".underscore

两种选择方式都会让步 "camel_cased_name" . 您可以查看更多详细信息 here

class String
   # ruby mutation methods have the expectation to return self if a mutation occurred, nil otherwise. (see http://www.ruby-doc.org/core-1.9.3/String.html#method-i-gsub-21)
   def to_underscore!
     gsub!(/(.)([A-Z])/,'\1_\2')
     downcase!
   end

   def to_underscore
     dup.tap { |s| s.to_underscore! }
   end
end

所以 "SomeCamelCase".to_underscore # =>"some_camel_case"

有一个Rails内置的方法叫做“下划线”,可以用于此目的

"CamelCaseString".underscore #=> "camel_case_string" 

“下划线”方法通常可以被视为“camelize”的逆方法

Rails does it :

   def underscore(camel_cased_word)
     camel_cased_word.to_s.gsub(/::/, '/').
       gsub(/([A-Z]+)([A-Z][a-z])/,'\1_\2').
       gsub(/([a-z\d])([A-Z])/,'\1_\2').
       tr("-", "_").
       downcase
   end

如果有人需要将下划线应用于带空格的字符串,并希望将其转换为下划线,那么您可以使用类似的方法

'your String will be converted To underscore'.parameterize.underscore
#your_string_will_be_converted_to_underscore

'your String will be converted To underscore'.parameterize('_')
#your_string_will_be_converted_to_underscore

如果还包含空格,则为CamelCases编写简短的单行线(如果中间有一个开头字母较小的单词,则无法正常工作):

a = "Test String"
a.gsub(' ', '').underscore
  
  => "test_string"

编辑:

接收器转换为蛇壳: http://rubydoc.info/gems/extlib/0.9.15/String#snake_case-instance_method

http://rubygems.org/gems/extlib )

def snake_case
  return downcase if match(/\A[A-Z]+\z/)
  gsub(/([A-Z]+)([A-Z][a-z])/, '\1_\2').
  gsub(/([a-z])([A-Z])/, '\1_\2').
  downcase
end

"FooBar".snake_case           #=> "foo_bar"
"HeadlineCNNNews".snake_case  #=> "headline_cnn_news"
"CNN".snake_case              #=> "cnn"

退房 蛇壳 Ruby Facets

处理以下情况,如下所示:

"SnakeCase".snakecase         #=> "snake_case"
"Snake-Case".snakecase        #=> "snake_case"
"Snake Case".snakecase        #=> "snake_case"
"Snake  -  Case".snakecase    #=> "snake_case"

发件人: https://github.com/rubyworks/facets/blob/master/lib/core/facets/string/snakecase.rb

class String

  # Underscore a string such that camelcase, dashes and spaces are
  # replaced by underscores. This is the reverse of {#camelcase},
  # albeit not an exact inverse.
  #
  #   "SnakeCase".snakecase         #=> "snake_case"
  #   "Snake-Case".snakecase        #=> "snake_case"
  #   "Snake Case".snakecase        #=> "snake_case"
  #   "Snake  -  Case".snakecase    #=> "snake_case"
  #
  # Note, this method no longer converts `::` to `/`, in that case
  # use the {#pathize} method instead.

  def snakecase
    #gsub(/::/, '/').
    gsub(/([A-Z]+)([A-Z][a-z])/,'\1_\2').
    gsub(/([a-z\d])([A-Z])/,'\1_\2').
    tr('-', '_').
    gsub(/\s/, '_').
    gsub(/__+/, '_').
    downcase
  end

  #
  alias_method :underscore, :snakecase

  # TODO: Add *separators to #snakecase, like camelcase.

end

ruby内核本身不支持将字符串从(大写)驼峰大小写转换为(也称为pascal大小写)下划线(也称为snake大小写)。

因此,您需要自己实现或使用现有的gem。

有一颗小红宝石叫做 幸运案例 它允许您轻松地将字符串从支持的10+个案例中的任意一个转换为另一个案例:

require 'lucky_case'

# convert to snake case string
LuckyCase.snake_case('CamelCaseString')      # => 'camel_case_string'
# or the opposite way
LuckyCase.pascal_case('camel_case_string')   # => 'CamelCaseString'

require 'lucky_case/string'

'CamelCaseString'.snake_case  # => 'camel_case_string'
'CamelCaseString'.snake_case! # => 'camel_case_string' and overwriting original

有关更多示例和文档,请查看官方存储库:

https://github.com/magynhard/lucky_case

class String

  # \n returns the capture group of "n" index
  def snakize
    self.gsub(/::/, '/')
    .gsub(/([a-z\d])([A-Z])/, "\1_\2")
    .downcase
  end

  # or

  def snakize
    self.gsub(/::/, '/')
    .gsub(/([a-z\d])([A-Z])/) do
      "#{$1}_#{$2}"
    end
    .downcase
  end

end

猴斑 String 班有些类以两个或更多大写字母开头。

我跑步有困难 "CamelCaseString".underscore 在rake任务中。这帮助了我:

ActiveSupport::Inflector.underscore "CamelCaseString"
=> "camel_case_string"