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"
Enable more predictable duck-typing on String-like classes. See Object#acts_like?.
# File lib/active_support/core_ext/string/behavior.rb, line 3 def acts_like_string? true end
# File lib/active_support/json/encoding.rb, line 179 def as_json(options = nil) self end
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
# File lib/active_support/core_ext/string/access.rb, line 11 def at(position) mb_chars[position, 1].to_s end
A string is blank if it’s empty or contains whitespaces only:
"".blank? # => true " ".blank? # => true " something here ".blank? # => false
# File lib/active_support/core_ext/object/blank.rb, line 95 def blank? self !~ /\S/ end
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"
# File lib/active_support/core_ext/string/inflections.rb, line 55 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
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"
# File lib/active_support/core_ext/string/inflections.rb, line 140 def classify ActiveSupport::Inflector.classify(self) end
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.
Examples
"Module".constantize # => Module "Class".constantize # => Class
# File lib/active_support/core_ext/string/inflections.rb, line 42 def constantize ActiveSupport::Inflector.constantize(self) end
Replaces underscores with dashes in the string.
"puni_puni" # => "puni-puni"
# File lib/active_support/core_ext/string/inflections.rb, line 89 def dasherize ActiveSupport::Inflector.dasherize(self) end
Removes the module part from the constant expression in the string.
"ActiveRecord::CoreExtensions::String::Inflections".demodulize # => "Inflections" "Inflections".demodulize # => "Inflections"
# File lib/active_support/core_ext/string/inflections.rb, line 97 def demodulize ActiveSupport::Inflector.demodulize(self) end
# File lib/active_support/json/encoding.rb, line 180 def encode_json(encoder) encoder.escape(self) end
# File lib/active_support/core_ext/string/encoding.rb, line 3 def encoding_aware? true end
The inverse of String#include?. Returns true if the string does not include the other string.
# File lib/active_support/core_ext/string/exclude.rb, line 3 def exclude?(string) !include?(string) end
Returns the first character of the string or the first limit characters.
Examples:
"hello".first # => "h" "hello".first(2) # => "he" "hello".first(10) # => "hello"
# 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
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"
# File lib/active_support/core_ext/string/inflections.rb, line 161 def foreign_key(separate_class_name_and_id_with_underscore = true) ActiveSupport::Inflector.foreign_key(self, separate_class_name_and_id_with_underscore) end
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
# File lib/active_support/core_ext/string/access.rb, line 21 def from(position) mb_chars[position..-1].to_s end
# File lib/active_support/core_ext/string/output_safety.rb, line 162 def html_safe ActiveSupport::SafeBuffer.new(self) end
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"
# File lib/active_support/core_ext/string/inflections.rb, line 149 def humanize ActiveSupport::Inflector.humanize(self) end
Wraps the current string in the ActiveSupport::StringInquirer class, which gives you a prettier way to test for equality. Example:
env = "production".inquiry env.production? # => true env.development? # => false
# File lib/active_support/core_ext/string/inquiry.rb, line 10 def inquiry ActiveSupport::StringInquirer.new(self) end
# File lib/active_support/core_ext/string/multibyte.rb, line 46 def is_utf8? #:nodoc 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
Returns the last character of the string or the last limit characters.
Examples:
"hello".last # => "o" "hello".last(2) # => "lo" "hello".last(10) # => "hello"
# 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 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.
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
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.
# File lib/active_support/core_ext/string/multibyte.rb, line 38 def mb_chars if ActiveSupport::Multibyte.proxy_class.consumes?(self) ActiveSupport::Multibyte.proxy_class.new(self) else self end end
Returns the codepoint of the first character of the string, assuming a single-byte character encoding:
"a".ord # => 97 "à".ord # => 224, in ISO-8859-1
This method is defined in Ruby 1.8 for Ruby 1.9 forward compatibility on these character encodings.
ActiveSupport::Multibyte::Chars#ord is forward compatible with Ruby 1.9 on UTF8 strings:
"a".mb_chars.ord # => 97 "à".mb_chars.ord # => 224, in UTF8
Note that the 224 is different in both examples. In ISO-8859-1 “à” is represented as a single byte, 224. In UTF8 it is represented with two bytes, namely 195 and 160, but its Unicode codepoint is 224. If we call ord on the UTF8 string “à” the return value will be 195. That is not an error, because UTF8 is unsupported, the call itself would be bogus.
# File lib/active_support/core_ext/string/conversions.rb, line 27 def ord self[0] end
Replaces special characters in a string so that it may be used as part of a ‘pretty’ URL.
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>
# File lib/active_support/core_ext/string/inflections.rb, line 116 def parameterize(sep = '-') ActiveSupport::Inflector.parameterize(self, sep) end
Returns the plural form of the word in the string.
"post".pluralize # => "posts" "octopus".pluralize # => "octopi" "sheep".pluralize # => "sheep" "words".pluralize # => "words" "the blue mailman".pluralize # => "the blue mailmen" "CamelOctopus".pluralize # => "CamelOctopi"
# File lib/active_support/core_ext/string/inflections.rb, line 19 def pluralize ActiveSupport::Inflector.pluralize(self) end
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"
# File lib/active_support/core_ext/string/inflections.rb, line 31 def singularize ActiveSupport::Inflector.singularize(self) end
Returns the string, first removing all whitespace on both ends of the string, and then changing remaining consecutive whitespace groups into one space each.
Examples:
%{ Multi-line string }.squish # => "Multi-line string" " foo bar \n \t boo".squish # => "foo bar boo"
# File lib/active_support/core_ext/string/filters.rb, line 12 def squish dup.squish! end
Performs a destructive squish. See String#squish.
# File lib/active_support/core_ext/string/filters.rb, line 17 def squish! strip! gsub!(/\s+/, ' ') self end
Strips indentation in heredocs.
For example in
if options[:usage] puts <<-USAGE.strip_heredoc This command does such and such. Supported options are: -h This message ... USAGE end
the user would see the usage message aligned against the left margin.
Technically, it looks for the least indented line in the whole string, and removes that amount of leading whitespace.
# File lib/active_support/core_ext/string/strip.rb, line 22 def strip_heredoc indent = scan(/^[ \t]*(?=\S)/).min.try(:size) || 0 gsub(/^[ \t]{#{indent}}/, '') end
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"
# File lib/active_support/core_ext/string/inflections.rb, line 126 def tableize ActiveSupport::Inflector.tableize(self) 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 titlecase.
"man from the boondocks".titleize # => "Man From The Boondocks" "x-men: the last stand".titleize # => "X Men: The Last Stand"
# File lib/active_support/core_ext/string/inflections.rb, line 71 def titleize ActiveSupport::Inflector.titleize(self) end
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"
# File lib/active_support/core_ext/string/access.rb, line 31 def to(position) mb_chars[0..position].to_s end
# File lib/active_support/core_ext/string/conversions.rb, line 42 def to_date return nil if self.blank? ::Date.new(*::Date._parse(self, false).values_at(:year, :mon, :mday)) end
# File lib/active_support/core_ext/string/conversions.rb, line 47 def to_datetime return nil if self.blank? d = ::Date._parse(self, false).values_at(:year, :mon, :mday, :hour, :min, :sec, :zone, :sec_fraction).map { |arg| arg || 0 } d[5] += d.pop ::DateTime.civil(*d) end
Form can be either :utc (default) or :local.
# File lib/active_support/core_ext/string/conversions.rb, line 35 def to_time(form = :utc) return nil if self.blank? d = ::Date._parse(self, false).values_at(:year, :mon, :mday, :hour, :min, :sec, :sec_fraction).map { |arg| arg || 0 } d[6] *= 1000000 ::Time.send("#{form}_time", *d) end
Truncates a given text after a given length if text is longer than length:
"Once upon a time in a world far far away".truncate(27) # => "Once upon a time in a wo..."
Pass a :separator to truncate text at a natural break:
"Once upon a time in a world far far away".truncate(27, :separator => ' ') # => "Once upon a time in a..."
The last characters will be replaced with the :omission string (defaults to “…”) for a total length not exceeding :length:
"And they found that many people were sleeping better.".truncate(25, :omission => "... (continued)") # => "And they f... (continued)"
# File lib/active_support/core_ext/string/filters.rb, line 38 def truncate(length, options = {}) text = self.dup options[:omission] ||= "..." length_with_room_for_omission = length - options[:omission].mb_chars.length chars = text.mb_chars stop = options[:separator] ? (chars.rindex(options[:separator].mb_chars, length_with_room_for_omission) || length_with_room_for_omission) : length_with_room_for_omission (chars.length > length ? chars[0...stop] + options[:omission] : text).to_s end
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.
"ActiveRecord".underscore # => "active_record" "ActiveRecord::Errors".underscore # => active_record/errors
# File lib/active_support/core_ext/string/inflections.rb, line 82 def underscore ActiveSupport::Inflector.underscore(self) end
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