Module: Enumerable

Included in:
ActiveSupport::Callbacks::CallbackChain, ActiveSupport::Dependencies::WatchStack
Defined in:
lib/active_support/core_ext/enumerable.rb,
lib/active_support/core_ext/object/json.rb

Instance Method Summary collapse

Instance Method Details

#as_json(options = nil) ⇒ Object

:nodoc:



131
132
133
 
# File 'lib/active_support/core_ext/object/json.rb', line 131

def as_json(options = nil) #:nodoc:
  to_a.as_json(options)
end

#exclude?(object) ⇒ Boolean

The negative of the Enumerable#include?. Returns true if the collection does not include the object.

Returns:

  • (Boolean) 


85
86
87
 
# File 'lib/active_support/core_ext/enumerable.rb', line 85

def exclude?(object)
  !include?(object)
end

#index_by ⇒ Object

Convert an enumerable to a hash.

people.index_by(&:login)
# => { "nextangle" => <Person ...>, "chade-" => <Person ...>, ...}
people.index_by { |person| "#{person.first_name} #{person.last_name}" }
# => { "Chade- Fowlersburg-e" => <Person ...>, "David Heinemeier Hansson" => <Person ...>, ...}



57
58
59
60
61
62
63
64
65
 
# File 'lib/active_support/core_ext/enumerable.rb', line 57

def index_by
  if block_given?
    result = {}
    each { |elem| result[yield(elem)] = elem }
    result
  else
    to_enum(:index_by) { size if respond_to?(:size) }
  end
end

#many? ⇒ Boolean

Returns true if the enumerable has more than 1 element. Functionally equivalent to enum.to_a.size > 1. Can be called with a block too, much like any?, so people.many? { |p| p.age > 26 } returns true if more than one person is over 26.

Returns:

  • (Boolean) 


71
72
73
74
75
76
77
78
79
80
81
 
# File 'lib/active_support/core_ext/enumerable.rb', line 71

def many?
  cnt = 0
  if block_given?
    any? do |element|
      cnt += 1 if yield element
      cnt > 1
    end
  else
    any? { (cnt += 1) > 1 }
  end
end

#pluck(*keys) ⇒ Object

Convert an enumerable to an array based on the given key.

[{ name: "David" }, { name: "Rafael" }, { name: "Aaron" }].pluck(:name)
# => ["David", "Rafael", "Aaron"]

[{ id: 1, name: "David" }, { id: 2, name: "Rafael" }].pluck(:id, :name)
# => [[1, "David"], [2, "Rafael"]]



107
108
109
110
111
112
113
 
# File 'lib/active_support/core_ext/enumerable.rb', line 107

def pluck(*keys)
  if keys.many?
    map { |element| keys.map { |key| element[key] } }
  else
    map { |element| element[keys.first] }
  end
end

#sum(identity = nil, &block) ⇒ Object

Calculates a sum from the elements.

payments.sum { |p| p.price * p.tax_rate }
payments.sum(&:price)

The latter is a shortcut for:

payments.inject(0) { |sum, p| sum + p.price }

It can also calculate the sum without the use of a block.

[5, 15, 10].sum # => 30
['foo', 'bar'].sum # => "foobar"
[[1, 2], [3, 1, 5]].sum # => [1, 2, 3, 1, 5]

The default sum of an empty list is zero. You can override this default:

[].sum(Payment.new(0)) { |i| i.amount } # => Payment.new(0)



31
32
33
34
35
36
37
38
39
 
# File 'lib/active_support/core_ext/enumerable.rb', line 31

def sum(identity = nil, &block)
  if identity
    _original_sum_with_required_identity(identity, &block)
  elsif block_given?
    map(&block).sum(identity)
  else
    inject(:+) || 0
  end
end

#without(*elements) ⇒ Object

Returns a copy of the enumerable without the specified elements.

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

{foo: 1, bar: 2, baz: 3}.without :bar
# => {foo: 1, baz: 3}



96
97
98
 
# File 'lib/active_support/core_ext/enumerable.rb', line 96

def without(*elements)
  reject { |element| elements.include?(element) }
end