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"
0x3000: fullwidth whitespace
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
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 " ".blank? # => true " something here ".blank? # => false
# File lib/active_support/core_ext/object/blank.rb, line 101 def blank? # 1.8 does not takes [:space:] properly if encoding_aware? self !~ /[^[:space:]]/ else self !~ NON_WHITESPACE_REGEXP end 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 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
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 178 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. See ActiveSupport::Inflector#constantize
Examples
"Module".constantize # => Module "Class".constantize # => Class "blargle".constantize # => NameError: wrong constant name blargle
# File lib/active_support/core_ext/string/inflections.rb, line 53 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 112 def dasherize ActiveSupport::Inflector.dasherize(self) end
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
.
# File lib/active_support/core_ext/string/inflections.rb, line 135 def deconstantize ActiveSupport::Inflector.deconstantize(self) end
Removes the module part from the constant expression in the string.
"ActiveRecord::CoreExtensions::String::Inflections".demodulize # => "Inflections" "Inflections".demodulize # => "Inflections"
See also deconstantize
.
# File lib/active_support/core_ext/string/inflections.rb, line 122 def demodulize ActiveSupport::Inflector.demodulize(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.
"hello".exclude? "lo" #=> false "hello".exclude? "ol" #=> true "hello".exclude? h #=> false
# File lib/active_support/core_ext/string/exclude.rb, line 8 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 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
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 183 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 187 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? 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 154 def parameterize(sep = '-') ActiveSupport::Inflector.parameterize(self, sep) end
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.
"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"
# 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
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
# File lib/active_support/core_ext/string/inflections.rb, line 65 def safe_constantize ActiveSupport::Inflector.safe_constantize(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 41 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:
%Q{ 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 #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 164 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 94 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
Converts a string to a Date value.
"1-1-2012".to_date #=> Sun, 01 Jan 2012 "01/01/2012".to_date #=> Sun, 01 Jan 2012 "2012-12-13".to_date #=> Thu, 13 Dec 2012 "12/13/2012".to_date #=> ArgumentError: invalid date
# File lib/active_support/core_ext/string/conversions.rb, line 48 def to_date return nil if self.blank? ::Date.new(*::Date._parse(self, false).values_at(:year, :mon, :mday)) end
Converts a string to a DateTime value.
"1-1-2012".to_datetime #=> Sun, 01 Jan 2012 00:00:00 +0000 "01/01/2012 23:59:59".to_datetime #=> Sun, 01 Jan 2012 23:59:59 +0000 "2012-12-13 12:50".to_datetime #=> Thu, 13 Dec 2012 12:50:00 +0000 "12/13/2012".to_datetime #=> ArgumentError: invalid date
# File lib/active_support/core_ext/string/conversions.rb, line 59 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, :offset).map { |arg| arg || 0 } d[6] *= 1000000 ::Time.send("#{form}_time", *d[0..6]) - d[7] 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.
"ActiveModel".underscore # => "active_model" "ActiveModel::Errors".underscore # => "active_model/errors"
# File lib/active_support/core_ext/string/inflections.rb, line 105 def underscore ActiveSupport::Inflector.underscore(self) end