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.

Private Class Methods

[](*args) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 85
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 70
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 168
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 98
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 181
def assoc(key)
  super(convert_key(key))
end
compact() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 371
def compact
  dup.tap(&:compact!)
end
convert_key(key) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 388
def convert_key(key)
  Symbol === key ? key.name : key
end
convert_value(value, conversion: nil) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 392
def convert_value(value, conversion: nil)
  if value.is_a? Hash
    value.nested_under_indifferent_access
  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
convert_value_to_hash(value) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 405
def convert_value_to_hash(value)
  if value.is_a? Hash
    value.to_hash
  elsif value.is_a?(Array)
    value.map { |e| convert_value_to_hash(e) }
  else
    value
  end
end
deep_symbolize_keys() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 320
def deep_symbolize_keys; to_hash.deep_symbolize_keys! end
default(key = (no_key = true)) 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 223
def default(key = (no_key = true))
  if no_key
    super()
  else
    super(convert_key(key))
  end
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 303
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 208
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 264
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 311
def except(*keys)
  dup.except!(*keys)
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 58
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 195
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 251
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) 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 151
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 273
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 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) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 328
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 298
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 283
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 289
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 323
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 416
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 361
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 366
def slice!(*keys)
  keys.map! { |key| convert_key(key) }
  super
end
store(key, value)
Alias for: []=
symbolize_keys() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 318
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 376
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!() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 321
def to_options!; self end
to_proc() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 383
def to_proc
  proc { |key| self[key] }
end
transform_keys(hash = NOT_GIVEN, &block) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 340
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) { |key| ... } click to toggle source
Calls superclass method
# File lib/active_support/hash_with_indifferent_access.rb, line 345
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) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 333
def transform_values(&block)
  return to_enum(:transform_values) unless block_given?
  dup.tap { |hash| hash.transform_values!(&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 132
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 424
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 237
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() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 62
def with_indifferent_access
  dup
end
without(*keys)
Alias for: except