Module: ActiveSupport::Inflector

Extended by:
Inflector
Included in:
Inflector
Defined in:
activesupport/lib/active_support/inflector/methods.rb,
activesupport/lib/active_support/inflector/inflections.rb,
activesupport/lib/active_support/inflector/transliterate.rb

Overview

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, you’ll need to correct it yourself (explained below).

Defined Under Namespace

Classes: Inflections

Instance Method Summary collapse

Instance Method Details

#camelize(term, uppercase_first_letter = true) ⇒ Object

By default, camelize converts strings to UpperCamelCase. If the argument to camelize is set to :lower then camelize produces lowerCamelCase.

camelize will also convert ‘/’ to ‘::’ which is useful for converting paths to namespaces.

Examples:

"active_model".camelize                # => "ActiveModel"
"active_model".camelize(:lower)        # => "activeModel"
"active_model/errors".camelize         # => "ActiveModel::Errors"
"active_model/errors".camelize(:lower) # => "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:

"SSLError".underscore.camelize # => "SslError"



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# File 'activesupport/lib/active_support/inflector/methods.rb', line 55

def camelize(term, uppercase_first_letter = true)
  string = term.to_s
  if uppercase_first_letter
    string = string.sub(/^[a-z\d]*/) { inflections.acronyms[$&] || $&.capitalize }
  else
    string = string.sub(/^(?:#{inflections.acronym_regex}(?=\b|[A-Z_])|\w)/) { $&.downcase }
  end
  string.gsub(/(?:_|(\/))([a-z\d]*)/i) { "#{$1}#{inflections.acronyms[$2] || $2.capitalize}" }.gsub('/', '::')
end

#classify(table_name) ⇒ Object

Create 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.)

Examples:

"egg_and_hams".classify # => "EggAndHam"
"posts".classify        # => "Post"

Singular names are not handled correctly:

"business".classify     # => "Busines"



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# File 'activesupport/lib/active_support/inflector/methods.rb', line 140

def classify(table_name)
  # strip out any leading schema name
  camelize(singularize(table_name.to_s.sub(/.*\./, '')))
end

#constantize(camel_cased_word) ⇒ Object

:nodoc:



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# File 'activesupport/lib/active_support/inflector/methods.rb', line 213

def constantize(camel_cased_word)
  names = camel_cased_word.split('::')
  names.shift if names.empty? || names.first.empty?

  constant = Object
  names.each do |name|
    constant = constant.const_defined?(name) ? constant.const_get(name) : constant.const_missing(name)
  end
  constant
end

#dasherize(underscored_word) ⇒ Object

Replaces underscores with dashes in the string.

Example:

"puni_puni" # => "puni-puni"



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# File 'activesupport/lib/active_support/inflector/methods.rb', line 149

def dasherize(underscored_word)
  underscored_word.gsub(/_/, '-')
end

#deconstantize(path) ⇒ Object

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

"Net::HTTP".deconstantize   # => "Net"
"::Net::HTTP".deconstantize # => "::Net"
"String".deconstantize      # => ""
"::String".deconstantize    # => ""
"".deconstantize            # => ""

See also demodulize.



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# File 'activesupport/lib/active_support/inflector/methods.rb', line 177

def deconstantize(path)
  path.to_s[0...(path.rindex('::') || 0)] # implementation based on the one in facets' Module#spacename
end

#demodulize(path) ⇒ Object

Removes the module part from the expression in the string:

"ActiveRecord::CoreExtensions::String::Inflections".demodulize # => "Inflections"
"Inflections".demodulize                                       # => "Inflections"

See also deconstantize.



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# File 'activesupport/lib/active_support/inflector/methods.rb', line 159

def demodulize(path)
  path = path.to_s
  if i = path.rindex('::')
    path[(i+2)..-1]
  else
    path
  end
end

#foreign_key(class_name, separate_class_name_and_id_with_underscore = true) ⇒ Object

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’.

Examples:

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



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# File 'activesupport/lib/active_support/inflector/methods.rb', line 189

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

#humanize(lower_case_and_underscored_word) ⇒ Object

Capitalizes the first word and turns underscores into spaces and strips a trailing “_id”, if any. Like titleize, this is meant for creating pretty output.

Examples:

"employee_salary" # => "Employee salary"
"author_id"       # => "Author"



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# File 'activesupport/lib/active_support/inflector/methods.rb', line 94

def humanize(lower_case_and_underscored_word)
  result = lower_case_and_underscored_word.to_s.dup
  inflections.humans.each { |(rule, replacement)| break if result.gsub!(rule, replacement) }
  result.gsub!(/_id$/, "")
  result.gsub!(/_/, ' ')
  result.gsub(/([a-z\d]*)/i) { |match|
    "#{inflections.acronyms[match] || match.downcase}"
  }.gsub(/^\w/) { $&.upcase }
end

#inflections ⇒ Object

Yields a singleton instance of Inflector::Inflections so you can specify additional inflector rules.

Example:

ActiveSupport::Inflector.inflections do |inflect|
  inflect.uncountable "rails"
end



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# File 'activesupport/lib/active_support/inflector/inflections.rb', line 166

def inflections
  if block_given?
    yield Inflections.instance
  else
    Inflections.instance
  end
end

#ordinalize(number) ⇒ Object

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

Examples:

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



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# File 'activesupport/lib/active_support/inflector/methods.rb', line 279

def ordinalize(number)
  if (11..13).include?(number.to_i.abs % 100)
    "#{number}th"
  else
    case number.to_i.abs % 10
      when 1; "#{number}st"
      when 2; "#{number}nd"
      when 3; "#{number}rd"
      else    "#{number}th"
    end
  end
end

#parameterize(string, sep = '-') ⇒ Object

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

Examples

class Person
  def to_param
    "#{id}-#{name.parameterize}"
  end
end

@person = Person.find(1)
# => #<Person id: 1, name: "Donald E. Knuth">

<%= link_to(@person.name, person_path(@person)) %>
# => <a href="/person/1-donald-e-knuth">Donald E. Knuth</a>



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# File 'activesupport/lib/active_support/inflector/transliterate.rb', line 82

def parameterize(string, sep = '-')
  # replace accented chars with their ascii equivalents
  parameterized_string = transliterate(string)
  # Turn unwanted chars into the separator
  parameterized_string.gsub!(/[^a-z0-9\-_]+/i, sep)
  unless sep.nil? || sep.empty?
    re_sep = Regexp.escape(sep)
    # No more than one of the separator in a row.
    parameterized_string.gsub!(/#{re_sep}{2,}/, sep)
    # Remove leading/trailing separator.
    parameterized_string.gsub!(/^#{re_sep}|#{re_sep}$/i, '')
  end
  parameterized_string.downcase
end

#pluralize(word) ⇒ Object

Returns the plural form of the word in the string.

Examples:

"post".pluralize             # => "posts"
"octopus".pluralize          # => "octopi"
"sheep".pluralize            # => "sheep"
"words".pluralize            # => "words"
"CamelOctopus".pluralize     # => "CamelOctopi"



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# File 'activesupport/lib/active_support/inflector/methods.rb', line 24

def pluralize(word)
  apply_inflections(word, inflections.plurals)
end

#safe_constantize(camel_cased_word) ⇒ Object

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

"Module".safe_constantize     # => Module
"Test::Unit".safe_constantize # => Test::Unit

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'
  "C".safe_constantize # => 'outside', same as ::C
end

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

"blargle".safe_constantize  # => nil
"UnknownModule".safe_constantize  # => nil
"UnknownModule::Foo::Bar".safe_constantize  # => nil



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# File 'activesupport/lib/active_support/inflector/methods.rb', line 258

def safe_constantize(camel_cased_word)
  begin
    constantize(camel_cased_word)
  rescue NameError => e
    raise unless e.message =~ /(uninitialized constant|wrong constant name) #{const_regexp(camel_cased_word)}$/ ||
      e.name.to_s == camel_cased_word.to_s
  rescue ArgumentError => e
    raise unless e.message =~ /not missing constant #{const_regexp(camel_cased_word)}\!$/
  end
end

#singularize(word) ⇒ Object

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

Examples:

"posts".singularize            # => "post"
"octopi".singularize           # => "octopus"
"sheep".singularize            # => "sheep"
"word".singularize             # => "word"
"CamelOctopi".singularize      # => "CamelOctopus"



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# File 'activesupport/lib/active_support/inflector/methods.rb', line 36

def singularize(word)
  apply_inflections(word, inflections.singulars)
end

#tableize(class_name) ⇒ Object

Create 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.

Examples

"RawScaledScorer".tableize # => "raw_scaled_scorers"
"egg_and_ham".tableize     # => "egg_and_hams"
"fancyCategory".tableize   # => "fancy_categories"



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# File 'activesupport/lib/active_support/inflector/methods.rb', line 126

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

#titleize(word) ⇒ Object

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.

titleize is also aliased as as titlecase.

Examples:

"man from the boondocks".titleize   # => "Man From The Boondocks"
"x-men: the last stand".titleize    # => "X Men: The Last Stand"
"TheManWithoutAPast".titleize       # => "The Man Without A Past"
"raiders_of_the_lost_ark".titleize  # => "Raiders Of The Lost Ark"



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# File 'activesupport/lib/active_support/inflector/methods.rb', line 115

def titleize(word)
  humanize(underscore(word)).gsub(/\b('?[a-z])/) { $1.capitalize }
end

#transliterate(string, replacement = "?") ⇒ Object

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 => lambda {|string| MyTransliterator.transliterate(string)}
  }
})

Now you can have different transliterations for each locale:

I18n.locale = :en
transliterate("Jürgen")
# => "Jurgen"

I18n.locale = :de
transliterate("Jürgen")
# => "Juergen"



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# File 'activesupport/lib/active_support/inflector/transliterate.rb', line 61

def transliterate(string, replacement = "?")
  I18n.transliterate(ActiveSupport::Multibyte::Unicode.normalize(
    ActiveSupport::Multibyte::Unicode.tidy_bytes(string), :c),
      :replacement => replacement)
end

#underscore(camel_cased_word) ⇒ Object

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

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

Examples:

"ActiveModel".underscore         # => "active_model"
"ActiveModel::Errors".underscore # => "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:

"SSLError".underscore.camelize # => "SslError"



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# File 'activesupport/lib/active_support/inflector/methods.rb', line 77

def underscore(camel_cased_word)
  word = camel_cased_word.to_s.dup
  word.gsub!(/::/, '/')
  word.gsub!(/(?:([A-Za-z\d])|^)(#{inflections.acronym_regex})(?=\b|[^a-z])/) { "#{$1}#{$1 && '_'}#{$2.downcase}" }
  word.gsub!(/([A-Z\d]+)([A-Z][a-z])/,'\1_\2')
  word.gsub!(/([a-z\d])([A-Z])/,'\1_\2')
  word.tr!("-", "_")
  word.downcase!
  word
end