Module: ActiveSupport::Inflector
- Extended by:
- Inflector
- Included in:
- Inflector
- Defined in:
- lib/active_support/inflector/methods.rb,
lib/active_support/inflector/inflections.rb,
lib/active_support/inflector/transliterate.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 or wish to define rules for languages other than English, please correct or add them yourself (explained below).
Defined Under Namespace
Classes: Inflections
Instance Method Summary collapse
-
#camelize(term, uppercase_first_letter = true) ⇒ Object
Converts strings to UpperCamelCase.
-
#classify(table_name) ⇒ Object
Creates a class name from a plural table name like Rails does for table names to models.
-
#constantize(camel_cased_word) ⇒ Object
Tries to find a constant with the name specified in the argument string.
-
#dasherize(underscored_word) ⇒ Object
Replaces underscores with dashes in the string.
-
#deconstantize(path) ⇒ Object
Removes the rightmost segment from the constant expression in the string.
-
#demodulize(path) ⇒ Object
Removes the module part from the expression in the string.
-
#foreign_key(class_name, separate_class_name_and_id_with_underscore = true) ⇒ Object
Creates a foreign key name from a class name.
-
#humanize(lower_case_and_underscored_word, options = {}) ⇒ Object
Tweaks an attribute name for display to end users.
-
#inflections(locale = :en) ⇒ Object
Yields a singleton instance of Inflector::Inflections so you can specify additional inflector rules.
-
#ordinal(number) ⇒ Object
Returns the suffix that should be added to a number to denote the position in an ordered sequence such as 1st, 2nd, 3rd, 4th.
-
#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.
-
#parameterize(string, sep = :unused, separator: '-', preserve_case: false) ⇒ Object
Replaces special characters in a string so that it may be used as part of a ‘pretty’ URL.
-
#pluralize(word, locale = :en) ⇒ Object
Returns the plural form of the word in the string.
-
#safe_constantize(camel_cased_word) ⇒ Object
Tries to find a constant with the name specified in the argument string.
-
#singularize(word, locale = :en) ⇒ Object
The reverse of #pluralize, returns the singular form of a word in a string.
-
#tableize(class_name) ⇒ Object
Creates the name of a table like Rails does for models to table names.
-
#titleize(word) ⇒ Object
Capitalizes all the words and replaces some characters in the string to create a nicer looking title.
-
#transliterate(string, replacement = "?".freeze) ⇒ Object
Replaces non-ASCII characters with an ASCII approximation, or if none exists, a replacement character which defaults to “?”.
-
#underscore(camel_cased_word) ⇒ Object
Makes an underscored, lowercase form from the expression in the string.
-
#upcase_first(string) ⇒ Object
Converts just the first character to uppercase.
Instance Method Details
#camelize(term, uppercase_first_letter = true) ⇒ Object
Converts strings to UpperCamelCase. If the uppercase_first_letter
parameter is set to false, then produces lowerCamelCase.
Also converts ‘/’ to ‘::’ which is useful for converting paths to namespaces.
camelize('active_model') # => "ActiveModel"
camelize('active_model', false) # => "activeModel"
camelize('active_model/errors') # => "ActiveModel::Errors"
camelize('active_model/errors', false) # => "activeModel::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:
camelize(underscore('SSLError')) # => "SslError"
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# File 'lib/active_support/inflector/methods.rb', line 66 def camelize(term, uppercase_first_letter = true) string = term.to_s if uppercase_first_letter string = string.sub(/^[a-z\d]*/) { |match| inflections.acronyms[match] || match.capitalize } else string = string.sub(/^(?:#{inflections.acronym_regex}(?=\b|[A-Z_])|\w)/) { |match| match.downcase } end string.gsub!(/(?:_|(\/))([a-z\d]*)/i) { "#{$1}#{inflections.acronyms[$2] || $2.capitalize}" } string.gsub!('/'.freeze, '::'.freeze) string end |
#classify(table_name) ⇒ Object
Creates 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).
classify('ham_and_eggs') # => "HamAndEgg"
classify('posts') # => "Post"
Singular names are not handled correctly:
classify('calculus') # => "Calculus"
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# File 'lib/active_support/inflector/methods.rb', line 186 def classify(table_name) # strip out any leading schema name camelize(singularize(table_name.to_s.sub(/.*\./, ''.freeze))) end |
#constantize(camel_cased_word) ⇒ Object
Tries to find a constant with the name specified in the argument string.
'Module'.constantize # => Module
'Foo::Bar'.constantize # => Foo::Bar
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/methods.rb', line 257 def constantize(camel_cased_word) names = camel_cased_word.split('::'.freeze) # Trigger a built-in NameError exception including the ill-formed constant in the message. Object.const_get(camel_cased_word) if names.empty? # Remove the first blank element in case of '::ClassName' notation. names.shift if names.size > 1 && names.first.empty? names.inject(Object) do |constant, name| if constant == Object constant.const_get(name) else candidate = constant.const_get(name) next candidate if constant.const_defined?(name, false) next candidate unless Object.const_defined?(name) # Go down the ancestors to check if it is owned directly. The check # stops when we reach Object or the end of ancestors tree. constant = constant.ancestors.inject(constant) do |const, ancestor| break const if ancestor == Object break ancestor if ancestor.const_defined?(name, false) const end # owner is in Object, so raise constant.const_get(name, false) end end end |
#dasherize(underscored_word) ⇒ Object
Replaces underscores with dashes in the string.
dasherize('puni_puni') # => "puni-puni"
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# File 'lib/active_support/inflector/methods.rb', line 194 def dasherize(underscored_word) underscored_word.tr('_'.freeze, '-'.freeze) end |
#deconstantize(path) ⇒ Object
Removes the rightmost segment from the constant expression in the string.
deconstantize('Net::HTTP') # => "Net"
deconstantize('::Net::HTTP') # => "::Net"
deconstantize('String') # => ""
deconstantize('::String') # => ""
deconstantize('') # => ""
See also #demodulize.
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# File 'lib/active_support/inflector/methods.rb', line 224 def deconstantize(path) path.to_s[0, path.rindex('::') || 0] # implementation based on the one in facets' Module#spacename end |
#demodulize(path) ⇒ Object
Removes the module part from the expression in the string.
demodulize('ActiveRecord::CoreExtensions::String::Inflections') # => "Inflections"
demodulize('Inflections') # => "Inflections"
demodulize('::Inflections') # => "Inflections"
demodulize('') # => ""
See also #deconstantize.
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# File 'lib/active_support/inflector/methods.rb', line 206 def demodulize(path) path = path.to_s if i = path.rindex('::') path[(i+2)..-1] else path end 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’.
foreign_key('Message') # => "message_id"
foreign_key('Message', false) # => "messageid"
foreign_key('Admin::Post') # => "post_id"
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# File 'lib/active_support/inflector/methods.rb', line 235 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, options = {}) ⇒ Object
Tweaks an attribute name for display to end users.
Specifically, performs these transformations:
-
Applies human inflection rules to the argument.
-
Deletes leading underscores, if any.
-
Removes a “_id” suffix if present.
-
Replaces underscores with spaces, if any.
-
Downcases all words except acronyms.
-
Capitalizes the first word.
The capitalization of the first word can be turned off by setting the :capitalize
option to false (default is true).
humanize('employee_salary') # => "Employee salary"
humanize('author_id') # => "Author"
humanize('author_id', capitalize: false) # => "author"
humanize('_id') # => "Id"
If “SSL” was defined to be an acronym:
humanize('ssl_error') # => "SSL error"
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# File 'lib/active_support/inflector/methods.rb', line 123 def humanize(lower_case_and_underscored_word, = {}) result = lower_case_and_underscored_word.to_s.dup inflections.humans.each { |(rule, replacement)| break if result.sub!(rule, replacement) } result.sub!(/\A_+/, ''.freeze) result.sub!(/_id\z/, ''.freeze) result.tr!('_'.freeze, ' '.freeze) result.gsub!(/([a-z\d]*)/i) do |match| "#{inflections.acronyms[match] || match.downcase}" end if .fetch(:capitalize, true) result.sub!(/\A\w/) { |match| match.upcase } end result end |
#inflections(locale = :en) ⇒ Object
Yields a singleton instance of Inflector::Inflections so you can specify additional inflector rules. If passed an optional locale, rules for other languages can be specified. If not specified, defaults to :en
. Only rules for English are provided.
ActiveSupport::Inflector.inflections(:en) do |inflect|
inflect.uncountable 'rails'
end
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# File 'lib/active_support/inflector/inflections.rb', line 234 def inflections(locale = :en) if block_given? yield Inflections.instance(locale) else Inflections.instance(locale) end end |
#ordinal(number) ⇒ Object
Returns the suffix that should be added to a number to denote the position in an ordered sequence such as 1st, 2nd, 3rd, 4th.
ordinal(1) # => "st"
ordinal(2) # => "nd"
ordinal(1002) # => "nd"
ordinal(1003) # => "rd"
ordinal(-11) # => "th"
ordinal(-1021) # => "st"
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# File 'lib/active_support/inflector/methods.rb', line 328 def ordinal(number) abs_number = number.to_i.abs if (11..13).include?(abs_number % 100) "th" else case abs_number % 10 when 1; "st" when 2; "nd" when 3; "rd" else "th" end 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.
ordinalize(1) # => "1st"
ordinalize(2) # => "2nd"
ordinalize(1002) # => "1002nd"
ordinalize(1003) # => "1003rd"
ordinalize(-11) # => "-11th"
ordinalize(-1021) # => "-1021st"
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# File 'lib/active_support/inflector/methods.rb', line 352 def ordinalize(number) "#{number}#{ordinal(number)}" end |
#parameterize(string, sep = :unused, separator: '-', preserve_case: false) ⇒ Object
Replaces special characters in a string so that it may be used as part of a ‘pretty’ URL.
parameterize("Donald E. Knuth") # => "donald-e-knuth"
parameterize("^trés|Jolie-- ") # => "tres-jolie"
To use a custom separator, override the ‘separator` argument.
parameterize("Donald E. Knuth", separator: '_') # => "donald_e_knuth"
parameterize("^trés|Jolie-- ", separator: '_') # => "tres_jolie"
To preserve the case of the characters in a string, use the ‘preserve_case` argument.
parameterize("Donald E. Knuth", preserve_case: true) # => "Donald-E-Knuth"
parameterize("^trés|Jolie-- ", preserve_case: true) # => "tres-Jolie"
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# File 'lib/active_support/inflector/transliterate.rb', line 82 def parameterize(string, sep = :unused, separator: '-', preserve_case: false) unless sep == :unused ActiveSupport::Deprecation.warn("Passing the separator argument as a positional parameter is deprecated and will soon be removed. Use `separator: '#{sep}'` instead.") separator = sep end # Replace accented chars with their ASCII equivalents. parameterized_string = transliterate(string) # Turn unwanted chars into the separator. parameterized_string.gsub!(/[^a-z0-9\-_]+/i, separator) unless separator.nil? || separator.empty? if separator == "-".freeze re_duplicate_separator = /-{2,}/ re_leading_trailing_separator = /^-|-$/i else re_sep = Regexp.escape(separator) re_duplicate_separator = /#{re_sep}{2,}/ re_leading_trailing_separator = /^#{re_sep}|#{re_sep}$/i end # No more than one of the separator in a row. parameterized_string.gsub!(re_duplicate_separator, separator) # Remove leading/trailing separator. parameterized_string.gsub!(re_leading_trailing_separator, ''.freeze) end parameterized_string.downcase! unless preserve_case parameterized_string end |
#pluralize(word, locale = :en) ⇒ Object
Returns the plural form of the word in the string.
If passed an optional locale
parameter, the word will be pluralized using rules defined for that language. By default, this parameter is set to :en
.
pluralize('post') # => "posts"
pluralize('octopus') # => "octopi"
pluralize('sheep') # => "sheep"
pluralize('words') # => "words"
pluralize('CamelOctopus') # => "CamelOctopi"
pluralize('ley', :es) # => "leyes"
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# File 'lib/active_support/inflector/methods.rb', line 29 def pluralize(word, locale = :en) apply_inflections(word, inflections(locale).plurals) end |
#safe_constantize(camel_cased_word) ⇒ Object
Tries to find a constant with the name specified in the argument string.
safe_constantize('Module') # => Module
safe_constantize('Foo::Bar') # => Foo::Bar
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'
safe_constantize('C') # => 'outside', same as ::C
end
nil
is returned when the name is not in CamelCase or the constant (or part of it) is unknown.
safe_constantize('blargle') # => nil
safe_constantize('UnknownModule') # => nil
safe_constantize('UnknownModule::Foo::Bar') # => nil
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# File 'lib/active_support/inflector/methods.rb', line 310 def safe_constantize(camel_cased_word) constantize(camel_cased_word) rescue NameError => e raise if e.name && !(camel_cased_word.to_s.split("::").include?(e.name.to_s) || e.name.to_s == camel_cased_word.to_s) rescue ArgumentError => e raise unless e. =~ /not missing constant #{const_regexp(camel_cased_word)}\!$/ end |
#singularize(word, locale = :en) ⇒ Object
The reverse of #pluralize, returns the singular form of a word in a string.
If passed an optional locale
parameter, the word will be singularized using rules defined for that language. By default, this parameter is set to :en
.
singularize('posts') # => "post"
singularize('octopi') # => "octopus"
singularize('sheep') # => "sheep"
singularize('word') # => "word"
singularize('CamelOctopi') # => "CamelOctopus"
singularize('leyes', :es) # => "ley"
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# File 'lib/active_support/inflector/methods.rb', line 46 def singularize(word, locale = :en) apply_inflections(word, inflections(locale).singulars) end |
#tableize(class_name) ⇒ 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.
tableize('RawScaledScorer') # => "raw_scaled_scorers"
tableize('ham_and_egg') # => "ham_and_eggs"
tableize('fancyCategory') # => "fancy_categories"
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# File 'lib/active_support/inflector/methods.rb', line 172 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 titlecase
.
titleize('man from the boondocks') # => "Man From The Boondocks"
titleize('x-men: the last stand') # => "X Men: The Last Stand"
titleize('TheManWithoutAPast') # => "The Man Without A Past"
titleize('raiders_of_the_lost_ark') # => "Raiders Of The Lost Ark"
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# File 'lib/active_support/inflector/methods.rb', line 162 def titleize(word) humanize(underscore(word)).gsub(/\b(?<!['’`])[a-z]/) { |match| match.capitalize } end |
#transliterate(string, replacement = "?".freeze) ⇒ Object
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: ->(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"
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# File 'lib/active_support/inflector/transliterate.rb', line 60 def transliterate(string, replacement = "?".freeze) I18n.transliterate(ActiveSupport::Multibyte::Unicode.normalize( ActiveSupport::Multibyte::Unicode.tidy_bytes(string), :c), :replacement => replacement) end |
#underscore(camel_cased_word) ⇒ Object
Makes an underscored, lowercase form from the expression in the string.
Changes ‘::’ to ‘/’ to convert namespaces to paths.
underscore('ActiveModel') # => "active_model"
underscore('ActiveModel::Errors') # => "active_model/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:
camelize(underscore('SSLError')) # => "SslError"
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# File 'lib/active_support/inflector/methods.rb', line 89 def underscore(camel_cased_word) return camel_cased_word unless camel_cased_word =~ /[A-Z-]|::/ word = camel_cased_word.to_s.gsub('::'.freeze, '/'.freeze) word.gsub!(/(?:(?<=([A-Za-z\d]))|\b)(#{inflections.acronym_regex})(?=\b|[^a-z])/) { "#{$1 && '_'.freeze }#{$2.downcase}" } word.gsub!(/([A-Z\d]+)([A-Z][a-z])/, '\1_\2'.freeze) word.gsub!(/([a-z\d])([A-Z])/, '\1_\2'.freeze) word.tr!("-".freeze, "_".freeze) word.downcase! word end |
#upcase_first(string) ⇒ Object
Converts just the first character to uppercase.
upcase_first('what a Lovely Day') # => "What a Lovely Day"
upcase_first('w') # => "W"
upcase_first('') # => ""
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# File 'lib/active_support/inflector/methods.rb', line 148 def upcase_first(string) string.length > 0 ? string[0].upcase.concat(string[1..-1]) : '' end |