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.

Public Class Methods

[] (*args)

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

new (constructor = nil)

Calls superclass method

# 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

Calls superclass method

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 184
def [](key)
  super(convert_key(key))
end

[]= (key, value)

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.

# 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

Also aliased as: regular_writer

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

Calls superclass method

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 197
def assoc(key)
  super(convert_key(key))
end

compact ()

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 390
def compact
  dup.tap(&:compact!)
end

deep_symbolize_keys ()

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 334
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'

Calls superclass method

# 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.

Calls superclass method

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 317
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

Calls superclass method

# 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"

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 280
def dup
  copy_defaults(self.class.new(self))
end

except (*keys)

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 activesupport/lib/active_support/hash_with_indifferent_access.rb, line 325
def except(*keys)
  dup.except!(*keys)
end

Also aliased as: without

extractable_options? ()

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

# 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"

Calls superclass method

# 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"

Calls superclass method

# 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)

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 activesupport/lib/active_support/hash_with_indifferent_access.rb, line 167
def key?(key)
  super(convert_key(key))
end

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

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.

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 287
def merge(*hashes, &block)
  dup.update(*hashes, &block)
end

merge! (*other_hashes, &block)

Alias for: update

nested_under_indifferent_access ()

# 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)

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 342
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}

Calls superclass method

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 312
def replace(other_hash)
  super(cast(other_hash))
end

reverse_merge (other_hash)

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 activesupport/lib/active_support/hash_with_indifferent_access.rb, line 297
def reverse_merge(other_hash)
  super(cast(other_hash))
end

Also aliased as: with_defaults

reverse_merge! (other_hash)

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

Calls superclass method Hash#reverse_merge!

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 303
def reverse_merge!(other_hash)
  super(cast(other_hash))
end

Also aliased as: with_defaults!

select (*args, &block)

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 337
def select(*args, &block)
  return to_enum(:select) unless block_given?
  dup.tap { |hash| hash.select!(*args, &block) }
end

slice (*keys)

Calls superclass method

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 380
def slice(*keys)
  keys.map! { |key| convert_key(key) }
  self.class.new(super)
end

slice! (*keys)

Calls superclass method Hash#slice!

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 385
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.

# 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 ()

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 332
def symbolize_keys; to_hash.symbolize_keys! end

Also aliased as: to_options

to_hash ()

Convert to a regular hash with string keys.

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 395
def to_hash
  copy = Hash[self]
  copy.transform_values! { |v| convert_value_to_hash(v) }
  copy_defaults(copy)
end

to_options ()

Alias for: symbolize_keys

to_options! ()

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 335
def to_options!; self end

to_proc ()

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 401
def to_proc
  proc { |key| self[key] }
end

transform_keys (hash = NOT_GIVEN, &block)

Calls superclass method

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 354
def transform_keys(hash = NOT_GIVEN, &block)
  if NOT_GIVEN.equal?(hash)
    if block_given?
      self.class.new(super(&block))
    else
      to_enum(:transform_keys)
    end
  else
    self.class.new(super)
  end
end

transform_keys! (hash = NOT_GIVEN, &block)

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 366
def transform_keys!(hash = NOT_GIVEN, &block)
  if NOT_GIVEN.equal?(hash)
    if block_given?
      replace(copy_defaults(transform_keys(&block)))
    else
      return to_enum(:transform_keys!)
    end
  else
    replace(copy_defaults(transform_keys(hash, &block)))
  end

  self
end

transform_values (&block)

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 347
def transform_values(&block)
  return to_enum(:transform_values) unless block_given?
  dup.tap { |hash| hash.transform_values!(&block) }
end

update (*other_hashes, &block)

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 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

Also aliased as: regular_update, merge!

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"]

Calls superclass method

# 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 ()

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

without (*keys)

Alias for: except