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Class: Array

Class Method Summary

  • .wrap(object)

    Wraps its argument in an array unless it is already an array (or array-like).

Instance Method Summary

Class Method Details

.wrap(object)

Wraps its argument in an array unless it is already an array (or array-like).

Specifically:

  • If the argument is nil an empty array is returned.

  • Otherwise, if the argument responds to to_ary it is invoked, and its result returned.

  • Otherwise, returns an array with the argument as its single element.

    Array.wrap(nil)       # => []
    Array.wrap([1, 2, 3]) # => [1, 2, 3]
    Array.wrap(0)         # => [0]

This method is similar in purpose to Kernel#Array, but there are some differences:

  • If the argument responds to to_ary the method is invoked. Kernel#Array moves on to try to_a if the returned value is nil, but wrap returns an array with the argument as its single element right away.

  • If the returned value from to_ary is neither nil nor an Array object, Kernel#Array raises an exception, while wrap does not, it just returns the value.

  • It does not call to_a on the argument, if the argument does not respond to to_ary it returns an array with the argument as its single element.

The last point is easily explained with some enumerables:

Array(foo: :bar)      # => [[:foo, :bar]]
Array.wrap(foo: :bar) # => [{:foo=>:bar}]

There’s also a related idiom that uses the splat operator:

[*object]

which returns [] for nil, but calls to Array(object) otherwise.

The differences with Kernel#Array explained above apply to the rest of objects.

[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/wrap.rb', line 39

def self.wrap(object)
  if object.nil?
    []
  elsif object.respond_to?(:to_ary)
    object.to_ary || [object]
  else
    [object]
  end
end

Instance Method Details

#append

The human way of thinking about adding stuff to the end of a list is with append.

[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/prepend_and_append.rb', line 5

alias_method :append,  :push unless [].respond_to?(:append)

#blank?true, false

An array is blank if it’s empty:

[].blank?      # => true
[1,2,3].blank? # => false
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/object/blank.rb', line 91

alias_method :blank?, :empty?

#deep_dup

Returns a deep copy of array.

array = [1, [2, 3]]
dup   = array.deep_dup
dup[1][2] = 4

array[1][2] # => nil
dup[1][2]   # => 4
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/object/deep_dup.rb', line 29

def deep_dup
  map(&:deep_dup)
end

#extract_options!

Extracts options from a set of arguments. Removes and returns the last element in the array if it’s a hash, otherwise returns a blank hash.

def options(*args)
  args.extract_options!
end

options(1, 2)        # => {}
options(1, 2, a: :b) # => {:a=>:b}
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/extract_options.rb', line 24

def extract_options!
  if last.is_a?(Hash) && last.extractable_options?
    pop
  else
    {}
  end
end

#fifth

Equal to self[4].

%w( a b c d e ).fifth # => "e"
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/access.rb', line 68

def fifth
  self[4]
end

#forty_two

Equal to self[41]. Also known as accessing “the reddit”.

(1..42).to_a.forty_two # => 42
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/access.rb', line 75

def forty_two
  self[41]
end

#fourth

Equal to self[3].

%w( a b c d e ).fourth # => "d"
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/access.rb', line 61

def fourth
  self[3]
end

#from(position)

Returns the tail of the array from position.

%w( a b c d ).from(0)  # => ["a", "b", "c", "d"]
%w( a b c d ).from(2)  # => ["c", "d"]
%w( a b c d ).from(10) # => []
%w().from(0)           # => []
%w( a b c d ).from(-2) # => ["c", "d"]
%w( a b c ).from(-10)  # => []
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/access.rb', line 12

def from(position)
  self[position, length] || []
end

#in_groups(number, fill_with = nil)

Splits or iterates over the array in number of groups, padding any remaining slots with fill_with unless it is false.

%w(1 2 3 4 5 6 7 8 9 10).in_groups(3) {|group| p group}
["1", "2", "3", "4"]
["5", "6", "7", nil]
["8", "9", "10", nil]

%w(1 2 3 4 5 6 7 8 9 10).in_groups(3, ' ') {|group| p group}
["1", "2", "3", "4"]
["5", "6", "7", " "]
["8", "9", "10", " "]

%w(1 2 3 4 5 6 7).in_groups(3, false) {|group| p group}
["1", "2", "3"]
["4", "5"]
["6", "7"]
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/grouping.rb', line 62

def in_groups(number, fill_with = nil)
  # size.div number gives minor group size;
  # size % number gives how many objects need extra accommodation;
  # each group hold either division or division + 1 items.
  division = size.div number
  modulo = size % number

  # create a new array avoiding dup
  groups = []
  start = 0

  number.times do |index|
    length = division + (modulo > 0 && modulo > index ? 1 : 0)
    groups << last_group = slice(start, length)
    last_group << fill_with if fill_with != false &&
      modulo > 0 && length == division
    start += length
  end

  if block_given?
    groups.each { |g| yield(g) }
  else
    groups
  end
end

#in_groups_of(number, fill_with = nil)

Splits or iterates over the array in groups of size number, padding any remaining slots with fill_with unless it is false.

%w(1 2 3 4 5 6 7 8 9 10).in_groups_of(3) {|group| p group}
["1", "2", "3"]
["4", "5", "6"]
["7", "8", "9"]
["10", nil, nil]

%w(1 2 3 4 5).in_groups_of(2, '&nbsp;') {|group| p group}
["1", "2"]
["3", "4"]
["5", "&nbsp;"]

%w(1 2 3 4 5).in_groups_of(2, false) {|group| p group}
["1", "2"]
["3", "4"]
["5"]
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/grouping.rb', line 22

def in_groups_of(number, fill_with = nil)
  if number.to_i <= 0
    raise ArgumentError,
      "Group size must be a positive integer, was #{number.inspect}"
  end

  if fill_with == false
    collection = self
  else
    # size % number gives how many extra we have;
    # subtracting from number gives how many to add;
    # modulo number ensures we don't add group of just fill.
    padding = (number - size % number) % number
    collection = dup.concat(Array.new(padding, fill_with))
  end

  if block_given?
    collection.each_slice(number) { |slice| yield(slice) }
  else
    collection.each_slice(number).to_a
  end
end

#inquiry

Wraps the array in an ArrayInquirer object, which gives a friendlier way to check its string-like contents.

pets = [:cat, :dog].inquiry

pets.cat?     # => true
pets.ferret?  # => false

pets.any?(:cat, :ferret)  # => true
pets.any?(:ferret, :alligator)  # => false
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/inquiry.rb', line 16

def inquiry
  ActiveSupport::ArrayInquirer.new(self)
end

#prepend

The human way of thinking about adding stuff to the beginning of a list is with prepend.

[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/prepend_and_append.rb', line 8

alias_method :prepend, :unshift unless [].respond_to?(:prepend)

#second

Equal to self[1].

%w( a b c d e ).second # => "b"
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/access.rb', line 47

def second
  self[1]
end

#second_to_last

Equal to self[-2].

%w( a b c d e ).second_to_last # => "d"
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/access.rb', line 89

def second_to_last
  self[-2]
end

#split(value = nil)

Divides the array into one or more subarrays based on a delimiting value or the result of an optional block.

[1, 2, 3, 4, 5].split(3)              # => [[1, 2], [4, 5]]
(1..10).to_a.split { |i| i % 3 == 0 } # => [[1, 2], [4, 5], [7, 8], [10]]
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/grouping.rb', line 93

def split(value = nil)
  arr = dup
  result = []
  if block_given?
    while (idx = arr.index { |i| yield i })
      result << arr.shift(idx)
      arr.shift
    end
  else
    while (idx = arr.index(value))
      result << arr.shift(idx)
      arr.shift
    end
  end
  result << arr
end

#third

Equal to self[2].

%w( a b c d e ).third # => "c"
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/access.rb', line 54

def third
  self[2]
end

#third_to_last

Equal to self[-3].

%w( a b c d e ).third_to_last # => "c"
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/access.rb', line 82

def third_to_last
  self[-3]
end

#to(position)

Returns the beginning of the array up to position.

%w( a b c d ).to(0)  # => ["a"]
%w( a b c d ).to(2)  # => ["a", "b", "c"]
%w( a b c d ).to(10) # => ["a", "b", "c", "d"]
%w().to(0)           # => []
%w( a b c d ).to(-2) # => ["a", "b", "c"]
%w( a b c ).to(-10)  # => []
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/access.rb', line 24

def to(position)
  if position >= 0
    take position + 1
  else
    self[0..position]
  end
end

#to_default_s

[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/conversions.rb', line 105

alias_method :to_default_s, :to_s

#to_formatted_s(format = :default) Also known as: #to_s

Extends #to_s to convert a collection of elements into a comma separated id list if :db argument is given as the format.

Blog.all.to_formatted_s(:db)  # => "1,2,3"
Blog.none.to_formatted_s(:db) # => "null"
[1,2].to_formatted_s          # => "[1, 2]"
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/conversions.rb', line 93

def to_formatted_s(format = :default)
  case format
  when :db
    if empty?
      "null"
    else
      collect(&:id).join(",")
    end
  else
    to_default_s
  end
end

#to_param

Calls to_param on all its elements and joins the result with slashes. This is used by url_for in Action Pack.

[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/object/to_query.rb', line 42

def to_param
  collect(&:to_param).join "/"
end

#to_query(key)

Converts an array into a string suitable for use as a URL query string, using the given key as the param name.

['Rails', 'coding'].to_query('hobbies') # => "hobbies%5B%5D=Rails&hobbies%5B%5D=coding"
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/object/to_query.rb', line 50

def to_query(key)
  prefix = "#{key}[]"

  if empty?
    nil.to_query(prefix)
  else
    collect { |value| value.to_query(prefix) }.join "&"
  end
end

#to_s(format = :default)

Alias for #to_formatted_s.

[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/conversions.rb', line 106

alias_method :to_s, :to_formatted_s

#to_sentence(options = {})

Converts the array to a comma-separated sentence where the last element is joined by the connector word.

You can pass the following options to change the default behavior. If you pass an option key that doesn’t exist in the list below, it will raise an ArgumentError.

Options

  • :words_connector - The sign or word used to join the elements in arrays with two or more elements (default: “, ”).

  • :two_words_connector - The sign or word used to join the elements in arrays with two elements (default: “ and ”).

  • :last_word_connector - The sign or word used to join the last element in arrays with three or more elements (default: “, and ”).

  • :locale - If i18n is available, you can set a locale and use the connector options defined on the ‘support.array’ namespace in the corresponding dictionary file.

Examples

[].to_sentence                      # => ""
['one'].to_sentence                 # => "one"
['one', 'two'].to_sentence          # => "one and two"
['one', 'two', 'three'].to_sentence # => "one, two, and three"

['one', 'two'].to_sentence(passing: 'invalid option')
# => ArgumentError: Unknown key: :passing. Valid keys are: :words_connector, :two_words_connector, :last_word_connector, :locale

['one', 'two'].to_sentence(two_words_connector: '-')
# => "one-two"

['one', 'two', 'three'].to_sentence(words_connector: ' or ', last_word_connector: ' or at least ')
# => "one or two or at least three"

Using :locale option:

# Given this locale dictionary:
#
#   es:
#     support:
#       array:
#         words_connector: " o "
#         two_words_connector: " y "
#         last_word_connector: " o al menos "

['uno', 'dos'].to_sentence(locale: :es)
# => "uno y dos"

['uno', 'dos', 'tres'].to_sentence(locale: :es)
# => "uno o dos o al menos tres"
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/conversions.rb', line 61

def to_sentence(options = {})
  options.assert_valid_keys(:words_connector, :two_words_connector, :last_word_connector, :locale)

  default_connectors = {
    words_connector: ", ",
    two_words_connector: " and ",
    last_word_connector: ", and "
  }
  if defined?(I18n)
    i18n_connectors = I18n.translate(:'support.array', locale: options[:locale], default: {})
    default_connectors.merge!(i18n_connectors)
  end
  options = default_connectors.merge!(options)

  case length
  when 0
    ""
  when 1
    "#{self[0]}"
  when 2
    "#{self[0]}#{options[:two_words_connector]}#{self[1]}"
  else
    "#{self[0...-1].join(options[:words_connector])}#{options[:last_word_connector]}#{self[-1]}"
  end
end

#to_xml(options = {})

Returns a string that represents the array in XML by invoking to_xml on each element. Active Record collections delegate their representation in XML to this method.

All elements are expected to respond to to_xml, if any of them does not then an exception is raised.

The root node reflects the class name of the first element in plural if all elements belong to the same type and that’s not ::Hash:

customer.projects.to_xml

<?xml version="1.0" encoding="UTF-8"?>
<projects type="array">
  <project>
    <amount type="decimal">20000.0</amount>
    <customer-id type="integer">1567</customer-id>
    <deal-date type="date">2008-04-09</deal-date>
    #...
  </project>
  <project>
    <amount type="decimal">57230.0</amount>
    <customer-id type="integer">1567</customer-id>
    <deal-date type="date">2008-04-15</deal-date>
    #...
  </project>
</projects>

Otherwise the root element is “objects”:

[{ foo: 1, bar: 2}, { baz: 3}].to_xml

<?xml version="1.0" encoding="UTF-8"?>
<objects type="array">
  <object>
    <bar type="integer">2</bar>
    <foo type="integer">1</foo>
  </object>
  <object>
    <baz type="integer">3</baz>
  </object>
</objects>

If the collection is empty the root element is “nil-classes” by default:

[].to_xml

<?xml version="1.0" encoding="UTF-8"?>
<nil-classes type="array"/>

To ensure a meaningful root element use the :root option:

customer_with_no_projects.projects.to_xml(root: 'projects')

<?xml version="1.0" encoding="UTF-8"?>
<projects type="array"/>

By default name of the node for the children of root is root.singularize. You can change it with the :children option.

The options hash is passed downwards:

Message.all.to_xml(skip_types: true)

<?xml version="1.0" encoding="UTF-8"?>
<messages>
  <message>
    <created-at>2008-03-07T09:58:18+01:00</created-at>
    <id>1</id>
    <name>1</name>
    <updated-at>2008-03-07T09:58:18+01:00</updated-at>
    <user-id>1</user-id>
  </message>
</messages>
[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/conversions.rb', line 183

def to_xml(options = {})
  require "active_support/builder" unless defined?(Builder)

  options = options.dup
  options[:indent]  ||= 2
  options[:builder] ||= Builder::XmlMarkup.new(indent: options[:indent])
  options[:root]    ||= \
    if first.class != Hash && all? { |e| e.is_a?(first.class) }
      underscored = ActiveSupport::Inflector.underscore(first.class.name)
      ActiveSupport::Inflector.pluralize(underscored).tr("/", "_")
    else
      "objects"
    end

  builder = options[:builder]
  builder.instruct! unless options.delete(:skip_instruct)

  root = ActiveSupport::XmlMini.rename_key(options[:root].to_s, options)
  children = options.delete(:children) || root.singularize
  attributes = options[:skip_types] ? {} : { type: "array" }

  if empty?
    builder.tag!(root, attributes)
  else
    builder.tag!(root, attributes) do
      each { |value| ActiveSupport::XmlMini.to_tag(children, value, options) }
      yield builder if block_given?
    end
  end
end

#without(*elements)

Returns a copy of the Array without the specified elements.

people = ["David", "Rafael", "Aaron", "Todd"]
people.without "Aaron", "Todd"
# => ["David", "Rafael"]

Note: This is an optimization of Enumerable#without that uses Array#- instead of Array#reject for performance reasons.

[ GitHub ]

  
# File 'activesupport/lib/active_support/core_ext/array/access.rb', line 40

def without(*elements)
  self - elements
end