ActiveSupport::Inflector

• activesupport/lib/active_support/inflector.rb

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).

• camelize
• classify
• constantize
• dasherize
• demodulize
• foreign_key
• humanize
• inflections
• ordinalize
• parameterize
• pluralize
• singularize
• tableize
• titleize
• transliterate
• transliterate
• transliterate
• underscore

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"

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"

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.

Replaces underscores with dashes in the string.

Example:

  "puni_puni" # => "puni-puni"

Removes the module part from the expression in the string.

Examples:

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

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"

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"

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

Example:

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

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"

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 %>
  # => <a href="/person/1-donald-e-knuth">Donald E. Knuth</a>

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"

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".singularize             # => "word"
  "CamelOctopi".singularize      # => "CamelOctopus"

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"

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"

Replaces accented characters with their ascii equivalents.

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