method

underscore

v8.1.1 - Show latest stable - Class: ActiveSupport::Inflector

underscore(camel_cased_word)

public

Makes an underscored, lowercase form from the expression in the string.

Changes ‘::’ to ‘/’ to convert namespaces to paths.

underscore('ActiveModel')         # => "active_model"
underscore('ActiveModel::Errors') # => "active_model/errors"

As a rule of thumb you can think of underscore as the inverse of #camelize, though there are cases where that does not hold:

camelize(underscore('SSLError'))  # => "SslError"

# File activesupport/lib/active_support/inflector/methods.rb, line 99
    def underscore(camel_cased_word)
      return camel_cased_word.to_s.dup unless /[A-Z-]|::/.match?(camel_cased_word)
      word = camel_cased_word.to_s.gsub("::", "/")
      word.gsub!(inflections.acronyms_underscore_regex) { "#{$1 && '_' }#{$2.downcase}" }
      word.gsub!(/(?<=[A-Z])(?=[A-Z][a-z])|(?<=[a-z\d])(?=[A-Z])/, "_")
      word.tr!("-", "_")
      word.downcase!
      word
    end

underscore

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