Class: String

Inherits:
Object
  • Object
show all
Defined in:
lib/active_support/core_ext/string/inflections.rb,
lib/active_support/core_ext/string/access.rb,
lib/active_support/core_ext/string/behavior.rb,
lib/active_support/core_ext/string/multibyte.rb

Overview

String inflections define new methods on the String class to transform names for different purposes. For instance, you can figure out the name of a table from the name of a class.

"ScaleScore".tableize # => "scale_scores"

Instance Method Summary collapse

Instance Method Details

#acts_like_string? ⇒ Boolean

Enable more predictable duck-typing on String-like classes. See Object#acts_like?.

Returns:

  • (Boolean) 


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# File 'lib/active_support/core_ext/string/behavior.rb', line 3

def acts_like_string?
  true
end

#at(position) ⇒ Object

Returns the character at the position treating the string as an array (where 0 is the first character).

Examples:

"hello".at(0)  # => "h"
"hello".at(4)  # => "o"
"hello".at(10) # => ERROR if < 1.9, nil in 1.9



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# File 'lib/active_support/core_ext/string/access.rb', line 11

def at(position)
  mb_chars[position, 1].to_s
end

#camelize(first_letter = :upper) ⇒ Object Also known as: camelcase

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.

"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/core_ext/string/inflections.rb', line 78

def camelize(first_letter = :upper)
  case first_letter
    when :upper then ActiveSupport::Inflector.camelize(self, true)
    when :lower then ActiveSupport::Inflector.camelize(self, false)
  end
end

#classify ⇒ 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.)

"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/core_ext/string/inflections.rb', line 178

def classify
  ActiveSupport::Inflector.classify(self)
end

#constantize ⇒ Object

constantize tries to find a declared constant with the name specified in the string. It raises a NameError when the name is not in CamelCase or is not initialized. See ActiveSupport::Inflector.constantize

Examples

"Module".constantize  # => Module
"Class".constantize   # => Class
"blargle".constantize # => NameError: wrong constant name blargle



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# File 'lib/active_support/core_ext/string/inflections.rb', line 53

def constantize
  ActiveSupport::Inflector.constantize(self)
end

#dasherize ⇒ Object

Replaces underscores with dashes in the string.

"puni_puni" # => "puni-puni"



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# File 'lib/active_support/core_ext/string/inflections.rb', line 112

def dasherize
  ActiveSupport::Inflector.dasherize(self)
end

#deconstantize ⇒ 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 'lib/active_support/core_ext/string/inflections.rb', line 135

def deconstantize
  ActiveSupport::Inflector.deconstantize(self)
end

#demodulize ⇒ Object

Removes the module part from the constant expression in the string.

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

See also deconstantize.



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# File 'lib/active_support/core_ext/string/inflections.rb', line 122

def demodulize
  ActiveSupport::Inflector.demodulize(self)
end

#first(limit = 1) ⇒ Object

Returns the first character of the string or the first limit characters.

Examples:

"hello".first     # => "h"
"hello".first(2)  # => "he"
"hello".first(10) # => "hello"



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# File 'lib/active_support/core_ext/string/access.rb', line 41

def first(limit = 1)
  if limit == 0
    ''
  elsif limit >= size
    self
  else
    mb_chars[0...limit].to_s
  end
end

#foreign_key(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/core_ext/string/inflections.rb', line 199

def foreign_key(separate_class_name_and_id_with_underscore = true)
  ActiveSupport::Inflector.foreign_key(self, separate_class_name_and_id_with_underscore)
end

#from(position) ⇒ Object

Returns the remaining of the string from the position treating the string as an array (where 0 is the first character).

Examples:

"hello".from(0)  # => "hello"
"hello".from(2)  # => "llo"
"hello".from(10) # => "" if < 1.9, nil in 1.9



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# File 'lib/active_support/core_ext/string/access.rb', line 21

def from(position)
  mb_chars[position..-1].to_s
end

#humanize ⇒ Object

Capitalizes the first word, turns underscores into spaces, and strips ‘_id’. Like titleize, this is meant for creating pretty output.

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



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# File 'lib/active_support/core_ext/string/inflections.rb', line 187

def humanize
  ActiveSupport::Inflector.humanize(self)
end

#is_utf8? ⇒ Boolean

Returns true if the string has UTF-8 semantics (a String used for purely byte resources is unlikely to have them), returns false otherwise.

Returns:

  • (Boolean) 


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# File 'lib/active_support/core_ext/string/multibyte.rb', line 68

def is_utf8?
  case encoding
    when Encoding::UTF_8
      valid_encoding?
    when Encoding::ASCII_8BIT, Encoding::US_ASCII
      dup.force_encoding(Encoding::UTF_8).valid_encoding?
    else
      false
  end
end

#last(limit = 1) ⇒ Object

Returns the last character of the string or the last limit characters.

Examples:

"hello".last     # => "o"
"hello".last(2)  # => "lo"
"hello".last(10) # => "hello"



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# File 'lib/active_support/core_ext/string/access.rb', line 57

def last(limit = 1)
  if limit == 0
    ''
  elsif limit >= size
    self
  else
    mb_chars[(-limit)..-1].to_s
  end
end

#mb_chars ⇒ Object

Multibyte proxy

mb_chars is a multibyte safe proxy for string methods.

In Ruby 1.8 and older it creates and returns an instance of the ActiveSupport::Multibyte::Chars class which encapsulates the original string. A Unicode safe version of all the String methods are defined on this proxy class. If the proxy class doesn’t respond to a certain method, it’s forwarded to the encapsulated string.

name = 'Claus Müller'
name.reverse # => "rell??M sualC"
name.length  # => 13

name.mb_chars.reverse.to_s # => "rellüM sualC"
name.mb_chars.length       # => 12

In Ruby 1.9 and newer mb_chars returns self because String is (mostly) encoding aware. This means that it becomes easy to run one version of your code on multiple Ruby versions.

Method chaining

All the methods on the Chars proxy which normally return a string will return a Chars object. This allows method chaining on the result of any of these methods.

name.mb_chars.reverse.length # => 12

Interoperability and configuration

The Chars object tries to be as interchangeable with String objects as possible: sorting and comparing between String and Char work like expected. The bang! methods change the internal string representation in the Chars object. Interoperability problems can be resolved easily with a to_s call.

For more information about the methods defined on the Chars proxy see ActiveSupport::Multibyte::Chars. For information about how to change the default Multibyte behavior see ActiveSupport::Multibyte.



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# File 'lib/active_support/core_ext/string/multibyte.rb', line 39

def mb_chars
  if ActiveSupport::Multibyte.proxy_class.consumes?(self)
    ActiveSupport::Multibyte.proxy_class.new(self)
  else
    self
  end
end

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



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# File 'lib/active_support/core_ext/string/inflections.rb', line 154

def parameterize(sep = '-')
  ActiveSupport::Inflector.parameterize(self, sep)
end

#pluralize(count = nil) ⇒ Object

Returns the plural form of the word in the string.

If the optional parameter count is specified, the singular form will be returned if count == 1. For any other value of count the plural will be returned.

Examples

"post".pluralize             # => "posts"
"octopus".pluralize          # => "octopi"
"sheep".pluralize            # => "sheep"
"words".pluralize            # => "words"
"the blue mailman".pluralize # => "the blue mailmen"
"CamelOctopus".pluralize     # => "CamelOctopi"
"apple".pluralize(1)         # => "apple"
"apple".pluralize(2)         # => "apples"



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# File 'lib/active_support/core_ext/string/inflections.rb', line 25

def pluralize(count = nil)
  if count == 1
    self
  else
    ActiveSupport::Inflector.pluralize(self)
  end
end

#safe_constantize ⇒ Object

safe_constantize tries to find a declared constant with the name specified in the string. It returns nil when the name is not in CamelCase or is not initialized. See ActiveSupport::Inflector.safe_constantize

Examples

"Module".safe_constantize  # => Module
"Class".safe_constantize   # => Class
"blargle".safe_constantize # => nil



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# File 'lib/active_support/core_ext/string/inflections.rb', line 65

def safe_constantize
  ActiveSupport::Inflector.safe_constantize(self)
end

#singularize ⇒ Object

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

"posts".singularize            # => "post"
"octopi".singularize           # => "octopus"
"sheep".singularize            # => "sheep"
"word".singularize             # => "word"
"the blue mailmen".singularize # => "the blue mailman"
"CamelOctopi".singularize      # => "CamelOctopus"



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# File 'lib/active_support/core_ext/string/inflections.rb', line 41

def singularize
  ActiveSupport::Inflector.singularize(self)
end

#tableize ⇒ Object

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.

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



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# File 'lib/active_support/core_ext/string/inflections.rb', line 164

def tableize
  ActiveSupport::Inflector.tableize(self)
end

#titleize ⇒ Object Also known as: titlecase

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 titlecase.

"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/core_ext/string/inflections.rb', line 94

def titleize
  ActiveSupport::Inflector.titleize(self)
end

#to(position) ⇒ Object

Returns the beginning of the string up to the position treating the string as an array (where 0 is the first character).

Examples:

"hello".to(0)  # => "h"
"hello".to(2)  # => "hel"
"hello".to(10) # => "hello"



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# File 'lib/active_support/core_ext/string/access.rb', line 31

def to(position)
  mb_chars[0..position].to_s
end

#underscore ⇒ Object

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

underscore will also change ‘::’ to ‘/’ to convert namespaces to paths.

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



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# File 'lib/active_support/core_ext/string/inflections.rb', line 105

def underscore
  ActiveSupport::Inflector.underscore(self)
end