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class ActiveSupport::HashWithIndifferentAccess

Hash With Indifferent Access

Implements a hash where keys :foo and "foo" are considered to be the same.

rgb = ActiveSupport::HashWithIndifferentAccess.new

rgb[:black] = '#000000'
rgb[:black]  # => '#000000'
rgb['black'] # => '#000000'

rgb['white'] = '#FFFFFF'
rgb[:white]  # => '#FFFFFF'
rgb['white'] # => '#FFFFFF'

Internally symbols are mapped to strings when used as keys in the entire writing interface (calling []=, merge, etc). This mapping belongs to the public interface. For example, given:

hash = ActiveSupport::HashWithIndifferentAccess.new(a: 1)

You are guaranteed that the key is returned as a string:

hash.keys # => ["a"]

Technically other types of keys are accepted:

hash = ActiveSupport::HashWithIndifferentAccess.new(a: 1)
hash[0] = 0
hash # => {"a"=>1, 0=>0}

but this class is intended for use cases where strings or symbols are the expected keys and it is convenient to understand both as the same. For example the params hash in Ruby on Rails.

Note that core extensions define Hash#with_indifferent_access:

rgb = { black: '#000000', white: '#FFFFFF' }.with_indifferent_access

which may be handy.

To access this class outside of Rails, require the core extension with:

require "active_support/core_ext/hash/indifferent_access"

which will, in turn, require this file.

Inherits From

Public class methods

[](*args)

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 85
def self.[](*args)
  new.merge!(Hash[*args])
end

new(constructor = nil)

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 70
def initialize(constructor = nil)
  if constructor.nil?
    super()
  elsif constructor.respond_to?(:to_hash)
    super()
    update(constructor)

    hash = constructor.is_a?(Hash) ? constructor : constructor.to_hash
    self.default = hash.default if hash.default
    self.default_proc = hash.default_proc if hash.default_proc
  else
    super(constructor)
  end
end

Public instance methods

[](key)

Same as Hash#[] where the key passed as argument can be either a string or a symbol:

counters = ActiveSupport::HashWithIndifferentAccess.new
counters[:foo] = 1

counters['foo'] # => 1
counters[:foo]  # => 1
counters[:zoo]  # => nil
Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 184
def [](key)
  super(convert_key(key))
end

[]=(key, value)

Also aliased as: regular_writer.

Assigns a new value to the hash:

hash = ActiveSupport::HashWithIndifferentAccess.new
hash[:key] = 'value'

This value can be later fetched using either :key or 'key'.

If the value is a Hash or contains one or multiple Hashes, they will be converted to HashWithIndifferentAccess.

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 101
def []=(key, value)
  regular_writer(convert_key(key), convert_value(value, conversion: :assignment))
end

assoc(key)

Same as Hash#assoc where the key passed as argument can be either a string or a symbol:

counters = ActiveSupport::HashWithIndifferentAccess.new
counters[:foo] = 1

counters.assoc('foo') # => ["foo", 1]
counters.assoc(:foo)  # => ["foo", 1]
counters.assoc(:zoo)  # => nil
Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 197
def assoc(key)
  super(convert_key(key))
end

compact()

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 387
def compact
  dup.tap(&:compact!)
end

deep_symbolize_keys()

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 336
def deep_symbolize_keys; to_hash.deep_symbolize_keys! end

default(key = (no_key = true))

Same as Hash#default where the key passed as argument can be either a string or a symbol:

hash = ActiveSupport::HashWithIndifferentAccess.new(1)
hash.default                   # => 1

hash = ActiveSupport::HashWithIndifferentAccess.new { |hash, key| key }
hash.default                   # => nil
hash.default('foo')            # => 'foo'
hash.default(:foo)             # => 'foo'
Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 239
def default(key = (no_key = true))
  if no_key
    super()
  else
    super(convert_key(key))
  end
end

delete(key)

Removes the specified key from the hash.

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 319
def delete(key)
  super(convert_key(key))
end

dig(*args)

Same as Hash#dig where the key passed as argument can be either a string or a symbol:

counters = ActiveSupport::HashWithIndifferentAccess.new
counters[:foo] = { bar: 1 }

counters.dig('foo', 'bar')     # => 1
counters.dig(:foo, :bar)       # => 1
counters.dig(:zoo)             # => nil
Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 224
def dig(*args)
  args[0] = convert_key(args[0]) if args.size > 0
  super(*args)
end

dup()

Returns a shallow copy of the hash.

hash = ActiveSupport::HashWithIndifferentAccess.new({ a: { b: 'b' } })
dup  = hash.dup
dup[:a][:c] = 'c'

hash[:a][:c] # => "c"
dup[:a][:c]  # => "c"
Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 280
def dup
  self.class.new(self).tap do |new_hash|
    set_defaults(new_hash)
  end
end

except(*keys)

Also aliased as: without.

Returns a hash with indifferent access that includes everything except given keys.

hash = { a: "x", b: "y", c: 10 }.with_indifferent_access
hash.except(:a, "b") # => {c: 10}.with_indifferent_access
hash                 # => { a: "x", b: "y", c: 10 }.with_indifferent_access
Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 327
def except(*keys)
  dup.except!(*keys)
end

extractable_options?()

Returns true so that Array#extract_options! finds members of this class.

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 58
def extractable_options?
  true
end

fetch(key, *extras)

Same as Hash#fetch where the key passed as argument can be either a string or a symbol:

counters = ActiveSupport::HashWithIndifferentAccess.new
counters[:foo] = 1

counters.fetch('foo')          # => 1
counters.fetch(:bar, 0)        # => 0
counters.fetch(:bar) { |key| 0 } # => 0
counters.fetch(:zoo)           # => KeyError: key not found: "zoo"
Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 211
def fetch(key, *extras)
  super(convert_key(key), *extras)
end

fetch_values(*indices, &block)

Returns an array of the values at the specified indices, but also raises an exception when one of the keys can’t be found.

hash = ActiveSupport::HashWithIndifferentAccess.new
hash[:a] = 'x'
hash[:b] = 'y'
hash.fetch_values('a', 'b') # => ["x", "y"]
hash.fetch_values('a', 'c') { |key| 'z' } # => ["x", "z"]
hash.fetch_values('a', 'c') # => KeyError: key not found: "c"
Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 267
def fetch_values(*indices, &block)
  indices.map! { |key| convert_key(key) }
  super
end

has_key?(key)

Alias for: key?.

include?(key)

Alias for: key?.

key?(key)

Also aliased as: include?, has_key?, member?.

Checks the hash for a key matching the argument passed in:

hash = ActiveSupport::HashWithIndifferentAccess.new
hash['key'] = 'value'
hash.key?(:key)  # => true
hash.key?('key') # => true
Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 167
def key?(key)
  super(convert_key(key))
end

member?(key)

Alias for: key?.

merge(*hashes, &block)

This method has the same semantics of update, except it does not modify the receiver but rather returns a new hash with indifferent access with the result of the merge.

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 289
def merge(*hashes, &block)
  dup.update(*hashes, &block)
end

merge!(*other_hashes, &block)

Alias for: update.

nested_under_indifferent_access()

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 66
def nested_under_indifferent_access
  self
end

regular_update(*other_hashes, &block)

Alias for: update.

regular_writer(key, value)

Alias for: []=.

reject(*args, &block)

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 344
def reject(*args, &block)
  return to_enum(:reject) unless block_given?
  dup.tap { |hash| hash.reject!(*args, &block) }
end

replace(other_hash)

Replaces the contents of this hash with other_hash.

h = { "a" => 100, "b" => 200 }
h.replace({ "c" => 300, "d" => 400 }) # => {"c"=>300, "d"=>400}
Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 314
def replace(other_hash)
  super(self.class.new(other_hash))
end

reverse_merge(other_hash)

Also aliased as: with_defaults.

Like merge but the other way around: Merges the receiver into the argument and returns a new hash with indifferent access as result:

hash = ActiveSupport::HashWithIndifferentAccess.new
hash['a'] = nil
hash.reverse_merge(a: 0, b: 1) # => {"a"=>nil, "b"=>1}
Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 299
def reverse_merge(other_hash)
  super(self.class.new(other_hash))
end

reverse_merge!(other_hash)

Also aliased as: with_defaults!.

Same semantics as reverse_merge but modifies the receiver in-place.

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 305
def reverse_merge!(other_hash)
  super(self.class.new(other_hash))
end

select(*args, &block)

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 339
def select(*args, &block)
  return to_enum(:select) unless block_given?
  dup.tap { |hash| hash.select!(*args, &block) }
end

slice(*keys)

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 377
def slice(*keys)
  keys.map! { |key| convert_key(key) }
  self.class.new(super)
end

slice!(*keys)

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 382
def slice!(*keys)
  keys.map! { |key| convert_key(key) }
  super
end

store(key, value, convert_value: true)

Assigns a new value to the hash:

hash = ActiveSupport::HashWithIndifferentAccess.new
hash[:key] = 'value'

This value can be later fetched using either :key or 'key'.

If the value is a Hash or contains one or multiple Hashes, they will be converted to HashWithIndifferentAccess. unless ‘convert_value: false` is set.

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 115
def store(key, value, convert_value: true)
  value = convert_value(value, conversion: :assignment) if convert_value
  regular_writer(convert_key(key), value)
end

symbolize_keys()

Also aliased as: to_options.

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 334
def symbolize_keys; to_hash.symbolize_keys! end

to_hash()

Convert to a regular hash with string keys.

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 392
def to_hash
  copy = Hash[self]
  copy.transform_values! { |v| convert_value_to_hash(v) }
  set_defaults(copy)
  copy
end

to_options()

Alias for: symbolize_keys.

to_options!()

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 337
def to_options!; self end

to_proc()

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 399
def to_proc
  proc { |key| self[key] }
end

transform_keys(hash = NOT_GIVEN, &block)

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 356
def transform_keys(hash = NOT_GIVEN, &block)
  return to_enum(:transform_keys) if NOT_GIVEN.equal?(hash) && !block_given?
  dup.tap { |h| h.transform_keys!(hash, &block) }
end

transform_keys!(hash = NOT_GIVEN, &block)

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 361
def transform_keys!(hash = NOT_GIVEN, &block)
  return to_enum(:transform_keys!) if NOT_GIVEN.equal?(hash) && !block_given?

  if hash.nil?
    super
  elsif NOT_GIVEN.equal?(hash)
    keys.each { |key| self[yield(key)] = delete(key) }
  elsif block_given?
    keys.each { |key| self[hash[key] || yield(key)] = delete(key) }
  else
    keys.each { |key| self[hash[key] || key] = delete(key) }
  end

  self
end

transform_values(&block)

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 349
def transform_values(&block)
  return to_enum(:transform_values) unless block_given?
  dup.tap { |hash| hash.transform_values!(&block) }
end

update(*other_hashes, &block)

Also aliased as: regular_update, merge!.

Updates the receiver in-place, merging in the hashes passed as arguments:

hash_1 = ActiveSupport::HashWithIndifferentAccess.new
hash_1[:key] = 'value'

hash_2 = ActiveSupport::HashWithIndifferentAccess.new
hash_2[:key] = 'New Value!'

hash_1.update(hash_2) # => {"key"=>"New Value!"}

hash = ActiveSupport::HashWithIndifferentAccess.new
hash.update({ "a" => 1 }, { "b" => 2 }) # => { "a" => 1, "b" => 2 }

The arguments can be either an ActiveSupport::HashWithIndifferentAccess or a regular Hash. In either case the merge respects the semantics of indifferent access.

If the argument is a regular hash with keys :key and "key" only one of the values end up in the receiver, but which one is unspecified.

When given a block, the value for duplicated keys will be determined by the result of invoking the block with the duplicated key, the value in the receiver, and the value in other_hash. The rules for duplicated keys follow the semantics of indifferent access:

hash_1[:key] = 10
hash_2['key'] = 12
hash_1.update(hash_2) { |key, old, new| old + new } # => {"key"=>22}
Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 148
def update(*other_hashes, &block)
  if other_hashes.size == 1
    update_with_single_argument(other_hashes.first, block)
  else
    other_hashes.each do |other_hash|
      update_with_single_argument(other_hash, block)
    end
  end
  self
end

values_at(*keys)

Returns an array of the values at the specified indices:

hash = ActiveSupport::HashWithIndifferentAccess.new
hash[:a] = 'x'
hash[:b] = 'y'
hash.values_at('a', 'b') # => ["x", "y"]
Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 253
def values_at(*keys)
  keys.map! { |key| convert_key(key) }
  super
end

with_defaults(other_hash)

Alias for: reverse_merge.

with_defaults!(other_hash)

Alias for: reverse_merge!.

with_indifferent_access()

Source code GitHub 
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 62
def with_indifferent_access
  dup
end

without(*keys)

Alias for: except.

Definition files