ActiveSupport::Inflector (original) (raw)

Active Support Inflector

The Inflector transforms words from singular to plural, class names to table names, modularized class names to ones without, and class names to foreign keys. The default inflections for pluralization, singularization, and uncountable words are kept in inflections.rb.

The Rails core team has stated patches for the inflections library will not be accepted in order to avoid breaking legacy applications which may be relying on errant inflections. If you discover an incorrect inflection and require it for your application or wish to define rules for languages other than English, please correct or add them yourself (explained below).

Namespace

Methods

C

D

F

H

I

O

P

S

T

U

Constants

ALLOWED_ENCODINGS_FOR_TRANSLITERATE = [Encoding::UTF_8, Encoding::US_ASCII, Encoding::GB18030].freeze

Instance Public methods

camelize(term, uppercase_first_letter = true)Link

Converts strings to UpperCamelCase. If the uppercase_first_letter parameter is set to false, then produces lowerCamelCase.

Also converts ‘/’ to ‘::’ which is useful for converting paths to namespaces.

camelize('active_model')                # => "ActiveModel"
camelize('active_model', false)         # => "activeModel"
camelize('active_model/errors')         # => "ActiveModel::Errors"
camelize('active_model/errors', false)  # => "activeModel::Errors"

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

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

Source: show | on GitHub

def camelize(term, uppercase_first_letter = true) string = term.to_s

if !uppercase_first_letter || uppercase_first_letter == :lower string = string.sub(inflections.acronyms_camelize_regex) { |match| match.downcase! || match } elsif string.match?(/\A[a-z\d]\z/) return inflections.acronyms[string]&.dup || string.capitalize else string = string.sub(/^[a-z\d]/) { |match| inflections.acronyms[match] || match.capitalize! || match } end string.gsub!(/(?:_|(/))([a-z\d]*)/i) do word = $2 substituted = inflections.acronyms[word] || word.capitalize! || word $1 ? "::#{substituted}" : substituted end string end

Creates a class name from a plural table name like Rails does for table names to models. Note that this returns a string and not a Class. (To convert to an actual class follow classify with constantize.)

classify('ham_and_eggs') # => "HamAndEgg"
classify('posts')        # => "Post"

Singular names are not handled correctly:

classify('calculus')     # => "Calculu"

Source: show | on GitHub

def classify(table_name)

camelize(singularize(table_name.to_s.sub(/.*./, ""))) end

Tries to find a constant with the name specified in the argument string.

constantize('Module')   # => Module
constantize('Foo::Bar') # => Foo::Bar

The name is assumed to be the one of a top-level constant, no matter whether it starts with “::” or not. No lexical context is taken into account:

C = 'outside'
module M
  C = 'inside'
  C                # => 'inside'
  constantize('C') # => 'outside', same as ::C
end

NameError is raised when the name is not in CamelCase or the constant is unknown.

Source: show | on GitHub

def constantize(camel_cased_word) Object.const_get(camel_cased_word) end

Replaces underscores with dashes in the string.

dasherize('puni_puni') # => "puni-puni"

Source: show | on GitHub

def dasherize(underscored_word) underscored_word.tr("_", "-") end

Removes the rightmost segment from the constant expression in the string.

deconstantize('Net::HTTP')   # => "Net"
deconstantize('::Net::HTTP') # => "::Net"
deconstantize('String')      # => ""
deconstantize('::String')    # => ""
deconstantize('')            # => ""

See also demodulize.

Source: show | on GitHub

def deconstantize(path) path.to_s[0, path.rindex("::") || 0] end

Removes the module part from the expression in the string.

demodulize('ActiveSupport::Inflector::Inflections') # => "Inflections"
demodulize('Inflections')                           # => "Inflections"
demodulize('::Inflections')                         # => "Inflections"
demodulize('')                                      # => ""

See also deconstantize.

Source: show | on GitHub

def demodulize(path) path = path.to_s if i = path.rindex("::") path[(i + 2), path.length] else path end end

Converts the first character in the string to lowercase.

downcase_first('If they enjoyed The Matrix') # => "if they enjoyed The Matrix"
downcase_first('I')                          # => "i"
downcase_first('')                           # => ""

Source: show | on GitHub

def downcase_first(string) string.length > 0 ? string[0].downcase.concat(string[1..-1]) : +"" end

foreign_key(class_name, separate_class_name_and_id_with_underscore = true)Link

Creates a foreign key name from a class name. separate_class_name_and_id_with_underscore sets whether the method should put ‘_’ between the name and ‘id’.

foreign_key('Message')        # => "message_id"
foreign_key('Message', false) # => "messageid"
foreign_key('Admin::Post')    # => "post_id"

Source: show | on GitHub

def foreign_key(class_name, separate_class_name_and_id_with_underscore = true) underscore(demodulize(class_name)) + (separate_class_name_and_id_with_underscore ? "_id" : "id") end

Tweaks an attribute name for display to end users.

Specifically, performs these transformations:

The capitalization of the first word can be turned off by setting the :capitalize option to false (default is true).

The trailing ‘_id’ can be kept and capitalized by setting the optional parameter keep_id_suffix to true (default is false).

humanize('employee_salary')                  # => "Employee salary"
humanize('author_id')                        # => "Author"
humanize('author_id', capitalize: false)     # => "author"
humanize('_id')                              # => "Id"
humanize('author_id', keep_id_suffix: true)  # => "Author id"

If “SSL” was defined to be an acronym:

humanize('ssl_error') # => "SSL error"

Source: show | on GitHub

def humanize(lower_case_and_underscored_word, capitalize: true, keep_id_suffix: false) result = lower_case_and_underscored_word.to_s.dup

inflections.humans.each { |(rule, replacement)| break if result.sub!(rule, replacement) }

result.tr!("_", " ") result.lstrip! if !keep_id_suffix && lower_case_and_underscored_word&.end_with?("_id") result.delete_suffix!(" id") end

result.gsub!(/([a-z\d]+)/i) do |match| match.downcase! inflections.acronyms[match] || match end

if capitalize result.sub!(/\A\w/) do |match| match.upcase! match end end

result end

inflections(locale = :en)Link

Yields a singleton instance of Inflector::Inflections so you can specify additional inflector rules. If passed an optional locale, rules for other languages can be specified. If not specified, defaults to :en. Only rules for English are provided.

ActiveSupport::Inflector.inflections(:en) do |inflect|
  inflect.uncountable 'rails'
end

Source: show | on GitHub

def inflections(locale = :en) if block_given? yield Inflections.instance(locale) else Inflections.instance_or_fallback(locale) end end

Returns the suffix that should be added to a number to denote the position in an ordered sequence such as 1st, 2nd, 3rd, 4th.

ordinal(1)     # => "st"
ordinal(2)     # => "nd"
ordinal(1002)  # => "nd"
ordinal(1003)  # => "rd"
ordinal(-11)   # => "th"
ordinal(-1021) # => "st"

Source: show | on GitHub

def ordinal(number) I18n.translate("number.nth.ordinals", number: number) end

Turns a number into an ordinal string used to denote the position in an ordered sequence such as 1st, 2nd, 3rd, 4th.

ordinalize(1)     # => "1st"
ordinalize(2)     # => "2nd"
ordinalize(1002)  # => "1002nd"
ordinalize(1003)  # => "1003rd"
ordinalize(-11)   # => "-11th"
ordinalize(-1021) # => "-1021st"

Source: show | on GitHub

def ordinalize(number) I18n.translate("number.nth.ordinalized", number: number) end

parameterize(string, separator: "-", preserve_case: false, locale: nil)Link

Replaces special characters in a string so that it may be used as part of a ‘pretty’ URL.

parameterize("Donald E. Knuth") # => "donald-e-knuth"
parameterize("^très|Jolie-- ")  # => "tres-jolie"

To use a custom separator, override the separator argument.

parameterize("Donald E. Knuth", separator: '_') # => "donald_e_knuth"
parameterize("^très|Jolie__ ", separator: '_')  # => "tres_jolie"

To preserve the case of the characters in a string, use the preserve_case argument.

parameterize("Donald E. Knuth", preserve_case: true) # => "Donald-E-Knuth"
parameterize("^très|Jolie-- ", preserve_case: true) # => "tres-Jolie"

It preserves dashes and underscores unless they are used as separators:

parameterize("^très|Jolie__ ")                 # => "tres-jolie__"
parameterize("^très|Jolie-- ", separator: "_") # => "tres_jolie--"
parameterize("^très_Jolie-- ", separator: ".") # => "tres_jolie--"

If the optional parameter locale is specified, the word will be parameterized as a word of that language. By default, this parameter is set to nil and it will use the configured I18n.locale.

Source: show | on GitHub

def parameterize(string, separator: "-", preserve_case: false, locale: nil)

parameterized_string = transliterate(string, locale: locale)

parameterized_string.gsub!(/[^a-z0-9-_]+/i, separator)

unless separator.nil? || separator.empty? if separator == "-" re_duplicate_separator = /-{2,}/ re_leading_trailing_separator = /^-|-$/i else re_sep = Regexp.escape(separator) re_duplicate_separator = /#{re_sep}{2,}/ re_leading_trailing_separator = /^#{re_sep}|#{re_sep}$/i end

parameterized_string.gsub!(re_duplicate_separator, separator)

parameterized_string.gsub!(re_leading_trailing_separator, "")

end

parameterized_string.downcase! unless preserve_case parameterized_string end

pluralize(word, locale = :en)Link

Returns the plural form of the word in the string.

If passed an optional locale parameter, the word will be pluralized using rules defined for that language. By default, this parameter is set to :en.

pluralize('post')             # => "posts"
pluralize('octopus')          # => "octopi"
pluralize('sheep')            # => "sheep"
pluralize('words')            # => "words"
pluralize('CamelOctopus')     # => "CamelOctopi"
pluralize('ley', :es)         # => "leyes"

Source: show | on GitHub

def pluralize(word, locale = :en) apply_inflections(word, inflections(locale).plurals, locale) end

Tries to find a constant with the name specified in the argument string.

safe_constantize('Module')   # => Module
safe_constantize('Foo::Bar') # => Foo::Bar

The name is assumed to be the one of a top-level constant, no matter whether it starts with “::” or not. No lexical context is taken into account:

C = 'outside'
module M
  C = 'inside'
  C                     # => 'inside'
  safe_constantize('C') # => 'outside', same as ::C
end

nil is returned when the name is not in CamelCase or the constant (or part of it) is unknown.

safe_constantize('blargle')                  # => nil
safe_constantize('UnknownModule')            # => nil
safe_constantize('UnknownModule::Foo::Bar')  # => nil

Source: show | on GitHub

def safe_constantize(camel_cased_word) constantize(camel_cased_word) rescue NameError => e raise if e.name && !(camel_cased_word.to_s.split("::").include?(e.name.to_s) || e.name.to_s == camel_cased_word.to_s) rescue LoadError => e message = e.respond_to?(:original_message) ? e.original_message : e.message raise unless /Unable to autoload constant #{const_regexp(camel_cased_word)}/.match?(message) end

singularize(word, locale = :en)Link

The reverse of pluralize, returns the singular form of a word in a string.

If passed an optional locale parameter, the word will be singularized using rules defined for that language. By default, this parameter is set to :en.

singularize('posts')            # => "post"
singularize('octopi')           # => "octopus"
singularize('sheep')            # => "sheep"
singularize('word')             # => "word"
singularize('CamelOctopi')      # => "CamelOctopus"
singularize('leyes', :es)       # => "ley"

Source: show | on GitHub

def singularize(word, locale = :en) apply_inflections(word, inflections(locale).singulars, locale) end

Creates the name of a table like Rails does for models to table names. This method uses the pluralize method on the last word in the string.

tableize('RawScaledScorer') # => "raw_scaled_scorers"
tableize('ham_and_egg')     # => "ham_and_eggs"
tableize('fancyCategory')   # => "fancy_categories"

Source: show | on GitHub

def tableize(class_name) pluralize(underscore(class_name)) end

Capitalizes all the words and replaces some characters in the string to create a nicer looking title. titleize is meant for creating pretty output. It is not used in the Rails internals.

The trailing ‘_id’,‘Id’.. can be kept and capitalized by setting the optional parameter keep_id_suffix to true. By default, this parameter is false.

titleize('man from the boondocks')                       # => "Man From The Boondocks"
titleize('x-men: the last stand')                        # => "X Men: The Last Stand"
titleize('TheManWithoutAPast')                           # => "The Man Without A Past"
titleize('raiders_of_the_lost_ark')                      # => "Raiders Of The Lost Ark"
titleize('string_ending_with_id', keep_id_suffix: true)  # => "String Ending With Id"

Source: show | on GitHub

def titleize(word, keep_id_suffix: false) humanize(underscore(word), keep_id_suffix: keep_id_suffix).gsub(/\b(?<!\w['’`()])[a-z]/) do |match| match.capitalize end end

transliterate(string, replacement = "?", locale: nil)Link

Replaces non-ASCII characters with an ASCII approximation, or if none exists, a replacement character which defaults to “?”.

transliterate('Ærøskøbing')
# => "AEroskobing"

Default approximations are provided for Western/Latin characters, e.g, “ø”, “ñ”, “é”, “ß”, etc.

This method is I18n aware, so you can set up custom approximations for a locale. This can be useful, for example, to transliterate German’s “ü” and “ö” to “ue” and “oe”, or to add support for transliterating Russian to ASCII.

In order to make your custom transliterations available, you must set them as the i18n.transliterate.rule i18n key:

# Store the transliterations in locales/de.yml
i18n:
  transliterate:
    rule:
      ü: "ue"
      ö: "oe"

# Or set them using Ruby
I18n.backend.store_translations(:de, i18n: {
  transliterate: {
    rule: {
      'ü' => 'ue',
      'ö' => 'oe'
    }
  }
})

The value for i18n.transliterate.rule can be a simple Hash that maps characters to ASCII approximations as shown above, or, for more complex requirements, a Proc:

I18n.backend.store_translations(:de, i18n: {
  transliterate: {
    rule: ->(string) { MyTransliterator.transliterate(string) }
  }
})

Now you can have different transliterations for each locale:

transliterate('Jürgen', locale: :en)
# => "Jurgen"

transliterate('Jürgen', locale: :de)
# => "Juergen"

Transliteration is restricted to UTF-8, US-ASCII, and GB18030 strings. Other encodings will raise an ArgumentError.

Source: show | on GitHub

def transliterate(string, replacement = "?", locale: nil) raise ArgumentError, "Can only transliterate strings. Received #{string.class.name}" unless string.is_a?(String) raise ArgumentError, "Cannot transliterate strings with #{string.encoding} encoding" unless ALLOWED_ENCODINGS_FOR_TRANSLITERATE.include?(string.encoding)

return string.dup if string.ascii_only? string = string.dup if string.frozen?

input_encoding = string.encoding

string.force_encoding(Encoding::UTF_8) if string.encoding == Encoding::US_ASCII

string.encode!(Encoding::UTF_8, invalid: :replace, undef: :replace) if string.encoding == Encoding::GB18030

transliterated = I18n.transliterate( ActiveSupport::Multibyte::Unicode.tidy_bytes(string).unicode_normalize(:nfc), replacement: replacement, locale: locale )

transliterated.encode!(input_encoding, invalid: :replace, undef: :replace) if input_encoding != transliterated.encoding

transliterated end

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"

Source: show | on GitHub

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

Converts the first character in the string to uppercase.

upcase_first('what a Lovely Day') # => "What a Lovely Day"
upcase_first('w')                 # => "W"
upcase_first('')                  # => ""

Source: show | on GitHub

def upcase_first(string) string.length > 0 ? string[0].upcase.concat(string[1..-1]) : +"" end