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:

  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"

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"

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"

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"

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