Module: Inflector

Extended by:
Inflector
Included in:
Inflector
Defined in:
lib/active_support/inflector.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(lower_case_and_underscored_word, first_letter_in_uppercase = 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_record".camelize                # => "ActiveRecord"
"active_record".camelize(:lower)        # => "activeRecord"
"active_record/errors".camelize         # => "ActiveRecord::Errors"
"active_record/errors".camelize(:lower) # => "activeRecord::Errors"

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# File 'lib/active_support/inflector.rb', line 160

def camelize(lower_case_and_underscored_word, first_letter_in_uppercase = true)
  if first_letter_in_uppercase
    lower_case_and_underscored_word.to_s.gsub(/\/(.?)/) { "::#{$1.upcase}" }.gsub(/(?:^|_)(.)/) { $1.upcase }
  else
    lower_case_and_underscored_word.first + camelize(lower_case_and_underscored_word)[1..-1]
  end
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 'lib/active_support/inflector.rb', line 244

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

#constantize(camel_cased_word) ⇒ Object

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

"Module".constantize     # => Module
"Test::Unit".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".constantize # => 'outside', same as ::C
end

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


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# File 'lib/active_support/inflector.rb', line 278

def constantize(camel_cased_word)
  unless /\A(?:::)?([A-Z]\w*(?:::[A-Z]\w*)*)\z/ =~ camel_cased_word
    raise NameError, "#{camel_cased_word.inspect} is not a valid constant name!"
  end

  Object.module_eval("::#{$1}", __FILE__, __LINE__)
end

#dasherize(underscored_word) ⇒ Object

Replaces underscores with dashes in the string.

Example:

"puni_puni" # => "puni-puni"

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# File 'lib/active_support/inflector.rb', line 200

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

#demodulize(class_name_in_module) ⇒ Object

Removes the module part from the expression in the string.

Examples:

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

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# File 'lib/active_support/inflector.rb', line 219

def demodulize(class_name_in_module)
  class_name_in_module.to_s.gsub(/^.*::/, '')
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 'lib/active_support/inflector.rb', line 257

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 'lib/active_support/inflector.rb', line 210

def humanize(lower_case_and_underscored_word)
  lower_case_and_underscored_word.to_s.gsub(/_id$/, "").gsub(/_/, " ").capitalize
end

#inflectionsObject

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

Example:

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

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# File 'lib/active_support/inflector.rb', line 102

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"

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# File 'lib/active_support/inflector.rb', line 294

def ordinalize(number)
  if (11..13).include?(number.to_i % 100)
    "#{number}th"
  else
    case number.to_i % 10
      when 1; "#{number}st"
      when 2; "#{number}nd"
      when 3; "#{number}rd"
      else    "#{number}th"
    end
  end
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"
"the blue mailman".pluralize # => "the blue mailmen"
"CamelOctopus".pluralize     # => "CamelOctopi"

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# File 'lib/active_support/inflector.rb', line 119

def pluralize(word)
  result = word.to_s.dup

  if word.empty? || inflections.uncountables.include?(result.downcase)
    result
  else
    inflections.plurals.each { |(rule, replacement)| break if result.gsub!(rule, replacement) }
    result
  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".singluarize            # => "sheep"
"word".singluarize             # => "word"
"the blue mailmen".singularize # => "the blue mailman"
"CamelOctopi".singularize      # => "CamelOctopus"

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# File 'lib/active_support/inflector.rb', line 139

def singularize(word)
  result = word.to_s.dup

  if inflections.uncountables.include?(result.downcase)
    result
  else
    inflections.singulars.each { |(rule, replacement)| break if result.gsub!(rule, replacement) }
    result
  end
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 'lib/active_support/inflector.rb', line 230

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"

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

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

#underscore(camel_cased_word) ⇒ Object

The reverse of camelize. Makes an underscored, lowercase form from the expression in the string.

Changes '::' to '/' to convert namespaces to paths.

Examples:

"ActiveRecord".underscore         # => "active_record"
"ActiveRecord::Errors".underscore # => active_record/errors

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# File 'lib/active_support/inflector.rb', line 188

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