class ActiveSupport::HashWithIndifferentAccess

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.

Private Class Methods

[](*args) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 83
def self.[](*args)
  new.merge!(Hash[*args])
end
new(constructor = nil) click to toggle source
Calls superclass method
# File lib/active_support/hash_with_indifferent_access.rb, line 68
def initialize(constructor = nil)
  if 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
  elsif constructor.nil?
    super()
  else
    super(constructor)
  end
end

Private Instance Methods

[](key) click to toggle source

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
Calls superclass method
# File lib/active_support/hash_with_indifferent_access.rb, line 166
def [](key)
  super(convert_key(key))
end
[]=(key, value) click to toggle source

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'.

# File lib/active_support/hash_with_indifferent_access.rb, line 96
def []=(key, value)
  regular_writer(convert_key(key), convert_value(value, conversion: :assignment))
end
Also aliased as: regular_writer, store
assoc(key) click to toggle source

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
Calls superclass method
# File lib/active_support/hash_with_indifferent_access.rb, line 179
def assoc(key)
  super(convert_key(key))
end
compact() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 357
def compact
  dup.tap(&:compact!)
end
convert_key(key) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 374
def convert_key(key)
  key.kind_of?(Symbol) ? key.name : key
end
convert_value(value, conversion: nil) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 383
def convert_value(value, conversion: nil)
  if value.is_a? Hash
    if conversion == :to_hash
      value.to_hash
    else
      value.nested_under_indifferent_access
    end
  elsif value.is_a?(Array)
    if conversion != :assignment || value.frozen?
      value = value.dup
    end
    value.map! { |e| convert_value(e, conversion: conversion) }
  else
    value
  end
end
deep_stringify_keys() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 311
def deep_stringify_keys; dup end
deep_stringify_keys!() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 309
def deep_stringify_keys!; self end
deep_symbolize_keys() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 316
def deep_symbolize_keys; to_hash.deep_symbolize_keys! end
default(*args) click to toggle source

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'
Calls superclass method
# File lib/active_support/hash_with_indifferent_access.rb, line 221
def default(*args)
  super(*args.map { |arg| convert_key(arg) })
end
delete(key) click to toggle source

Removes the specified key from the hash.

Calls superclass method
# File lib/active_support/hash_with_indifferent_access.rb, line 295
def delete(key)
  super(convert_key(key))
end
dig(*args) click to toggle source

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
Calls superclass method
# File lib/active_support/hash_with_indifferent_access.rb, line 206
def dig(*args)
  args[0] = convert_key(args[0]) if args.size > 0
  super(*args)
end
dup() click to toggle source

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"
# File lib/active_support/hash_with_indifferent_access.rb, line 256
def dup
  self.class.new(self).tap do |new_hash|
    set_defaults(new_hash)
  end
end
except(*keys) click to toggle source

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
# File lib/active_support/hash_with_indifferent_access.rb, line 303
def except(*keys)
  slice(*self.keys - keys.map { |key| convert_key(key) })
end
Also aliased as: without
extractable_options?() click to toggle source

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

# File lib/active_support/hash_with_indifferent_access.rb, line 56
def extractable_options?
  true
end
fetch(key, *extras) click to toggle source

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"
Calls superclass method
# File lib/active_support/hash_with_indifferent_access.rb, line 193
def fetch(key, *extras)
  super(convert_key(key), *extras)
end
fetch_values(*indices, &block) click to toggle source

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"
Calls superclass method
# File lib/active_support/hash_with_indifferent_access.rb, line 244
def fetch_values(*indices, &block)
  super(*indices.map { |key| convert_key(key) }, &block)
end
has_key?(key)
Alias for: key?
include?(key)
Alias for: key?
key?(key) click to toggle source

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
Calls superclass method
# File lib/active_support/hash_with_indifferent_access.rb, line 149
def key?(key)
  super(convert_key(key))
end
Also aliased as: include?, has_key?, member?
member?(key)
Alias for: key?
merge(*hashes, &block) click to toggle source

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.

# File lib/active_support/hash_with_indifferent_access.rb, line 265
def merge(*hashes, &block)
  dup.update(*hashes, &block)
end
merge!(*other_hashes, &block)
Alias for: update
nested_under_indifferent_access() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 64
def nested_under_indifferent_access
  self
end
regular_update(*other_hashes, &block)
Alias for: update
regular_writer(key, value)
Alias for: []=
reject(*args, &block) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 324
def reject(*args, &block)
  return to_enum(:reject) unless block_given?
  dup.tap { |hash| hash.reject!(*args, &block) }
end
replace(other_hash) click to toggle source

Replaces the contents of this hash with other_hash.

h = { "a" => 100, "b" => 200 }
h.replace({ "c" => 300, "d" => 400 }) # => {"c"=>300, "d"=>400}
Calls superclass method
# File lib/active_support/hash_with_indifferent_access.rb, line 290
def replace(other_hash)
  super(self.class.new(other_hash))
end
reverse_merge(other_hash) click to toggle source

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}
Calls superclass method Hash#reverse_merge
# File lib/active_support/hash_with_indifferent_access.rb, line 275
def reverse_merge(other_hash)
  super(self.class.new(other_hash))
end
Also aliased as: with_defaults
reverse_merge!(other_hash) click to toggle source

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

Calls superclass method Hash#reverse_merge!
# File lib/active_support/hash_with_indifferent_access.rb, line 281
def reverse_merge!(other_hash)
  super(self.class.new(other_hash))
end
Also aliased as: with_defaults!
select(*args, &block) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 319
def select(*args, &block)
  return to_enum(:select) unless block_given?
  dup.tap { |hash| hash.select!(*args, &block) }
end
set_defaults(target) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 400
def set_defaults(target)
  if default_proc
    target.default_proc = default_proc.dup
  else
    target.default = default
  end
end
slice(*keys) click to toggle source
Calls superclass method
# File lib/active_support/hash_with_indifferent_access.rb, line 347
def slice(*keys)
  keys.map! { |key| convert_key(key) }
  self.class.new(super)
end
slice!(*keys) click to toggle source
Calls superclass method Hash#slice!
# File lib/active_support/hash_with_indifferent_access.rb, line 352
def slice!(*keys)
  keys.map! { |key| convert_key(key) }
  super
end
store(key, value)
Alias for: []=
stringify_keys() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 310
def stringify_keys; dup end
stringify_keys!() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 308
def stringify_keys!; self end
symbolize_keys() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 314
def symbolize_keys; to_hash.symbolize_keys! end
Also aliased as: to_options
to_hash() click to toggle source

Convert to a regular hash with string keys.

# File lib/active_support/hash_with_indifferent_access.rb, line 362
def to_hash
  _new_hash = Hash.new
  set_defaults(_new_hash)

  each do |key, value|
    _new_hash[key] = convert_value(value, conversion: :to_hash)
  end
  _new_hash
end
to_options()
Alias for: symbolize_keys
to_options!() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 317
def to_options!; self end
transform_keys(*args, &block) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 334
def transform_keys(*args, &block)
  return to_enum(:transform_keys) unless block_given?
  dup.tap { |hash| hash.transform_keys!(*args, &block) }
end
transform_keys!() { |key| ... } click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 339
def transform_keys!
  return enum_for(:transform_keys!) { size } unless block_given?
  keys.each do |key|
    self[yield(key)] = delete(key)
  end
  self
end
transform_values(*args, &block) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 329
def transform_values(*args, &block)
  return to_enum(:transform_values) unless block_given?
  dup.tap { |hash| hash.transform_values!(*args, &block) }
end
update(*other_hashes, &block) click to toggle source

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}
# File lib/active_support/hash_with_indifferent_access.rb, line 130
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
Also aliased as: regular_update, merge!
update_with_single_argument(other_hash, block) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 408
def update_with_single_argument(other_hash, block)
  if other_hash.is_a? HashWithIndifferentAccess
    regular_update(other_hash, &block)
  else
    other_hash.to_hash.each_pair do |key, value|
      if block && key?(key)
        value = block.call(convert_key(key), self[key], value)
      end
      regular_writer(convert_key(key), convert_value(value))
    end
  end
end
values_at(*keys) click to toggle source

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"]
Calls superclass method
# File lib/active_support/hash_with_indifferent_access.rb, line 231
def values_at(*keys)
  super(*keys.map { |key| convert_key(key) })
end
with_defaults(other_hash)
Alias for: reverse_merge
with_defaults!(other_hash)
Alias for: reverse_merge!
with_indifferent_access() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 60
def with_indifferent_access
  dup
end
without(*keys)
Alias for: except