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).
- C
- D
- F
- H
- I
- O
- P
- S
- T
- U
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"
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"
Source: show
# File activesupport/lib/active_support/inflector/methods.rb, line 28 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.to_s[0].chr.downcase + camelize(lower_case_and_underscored_word)[1..-1] end end
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"
Source: show
# File activesupport/lib/active_support/inflector/inflections.rb, line 206 def classify(table_name) # strip out any leading schema name camelize(singularize(table_name.to_s.sub(/.*\./, ''))) end
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.
Source: show
# File activesupport/lib/active_support/inflector/methods.rb, line 107 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
Replaces underscores with dashes in the string.
Example:
"puni_puni" # => "puni-puni"
Source: show
# File activesupport/lib/active_support/inflector/methods.rb, line 62 def dasherize(underscored_word) underscored_word.gsub(/_/, '-') end
Removes the module part from the expression in the string.
Examples:
"ActiveRecord::CoreExtensions::String::Inflections".demodulize # => "Inflections" "Inflections".demodulize # => "Inflections"
Source: show
# File activesupport/lib/active_support/inflector/methods.rb, line 71 def demodulize(class_name_in_module) class_name_in_module.to_s.gsub(/^.*::/, '') end
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"
Source: show
# File activesupport/lib/active_support/inflector/methods.rb, line 83 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
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"
Source: show
# File activesupport/lib/active_support/inflector/inflections.rb, line 165 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$/, "").gsub(/_/, " ").capitalize end
Yields a singleton instance of Inflector::Inflections so you can specify additional inflector rules.
Example:
ActiveSupport::Inflector.inflections do |inflect| inflect.uncountable "rails" end
Source: show
# File activesupport/lib/active_support/inflector/inflections.rb, line 113 def inflections if block_given? yield Inflections.instance else Inflections.instance end 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" ordinalize(-11) # => "-11th" ordinalize(-1021) # => "-1021st"
Source: show
# File activesupport/lib/active_support/inflector/methods.rb, line 140 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
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"> <%Q link_to(@person.name, person_path(@person)) %> # => <a href="/person/1-donald-e-knuth">Donald E. Knuth</a>
Source: show
# File activesupport/lib/active_support/inflector/transliterate.rb, line 81 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\-_]+/, 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}$/, '') end parameterized_string.downcase end
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"
Source: show
# File activesupport/lib/active_support/inflector/inflections.rb, line 129 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
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"
Source: show
# File activesupport/lib/active_support/inflector/inflections.rb, line 148 def singularize(word) result = word.to_s.dup if inflections.uncountables.any? { |inflection| result =~ /\b(#{inflection})\Z/ } result else inflections.singulars.each { |(rule, replacement)| break if result.gsub!(rule, replacement) } result end end
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"
Source: show
# File activesupport/lib/active_support/inflector/inflections.rb, line 192 def tableize(class_name) pluralize(underscore(class_name)) end
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"
Source: show
# File activesupport/lib/active_support/inflector/inflections.rb, line 181 def titleize(word) humanize(underscore(word)).gsub(/\b('?[a-z])/) { $1.capitalize } end
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"
Source: show
# File activesupport/lib/active_support/inflector/transliterate.rb, line 60 def transliterate(string, replacement = "?") I18n.transliterate(ActiveSupport::Multibyte::Unicode.normalize( ActiveSupport::Multibyte::Unicode.tidy_bytes(string), :c), :replacement => replacement) end
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
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"
Source: show
# File activesupport/lib/active_support/inflector/methods.rb, line 48 def underscore(camel_cased_word) word = camel_cased_word.to_s.dup word.gsub!(/::/, '/') word.gsub!(/([A-Z]+)([A-Z][a-z])/,'\1_\2') word.gsub!(/([a-z\d])([A-Z])/,'\1_\2') word.tr!("-", "_") word.downcase! word end