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)

Source

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

new (constructor = nil)

Source

# File 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

Calls superclass method

Public Instance Methods

[] (key)

Source

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

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

[]= (key, value)

Source

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

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.

Also aliased as: regular_writer

assoc (key)

Source

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

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

compact ()

Source

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

deep_symbolize_keys ()

Source

# File 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))

Source

# File 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

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

delete (key)

Source

# File lib/active_support/hash_with_indifferent_access.rb, line 317
def delete(key)
  super(convert_key(key))
end

Removes the specified key from the hash.

Calls superclass method

dig (*args)

Source

# File 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

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

dup ()

Source

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

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"

except (*keys)

Source

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

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

Also aliased as: without

extractable_options? ()

Source

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

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

fetch (key, *extras)

Source

# File lib/active_support/hash_with_indifferent_access.rb, line 211
def fetch(key, *extras)
  super(convert_key(key), *extras)
end

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

fetch_values (*indices, &block)

Source

# File lib/active_support/hash_with_indifferent_access.rb, line 267
def fetch_values(*indices, &block)
  indices.map! { |key| convert_key(key) }
  super
end

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

has_key? (key)

Alias for: key?

include? (key)

Alias for: key?

key? (key)

Source

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

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

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

member? (key)

Alias for: key?

merge (*hashes, &block)

Source

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

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.

merge! (*other_hashes, &block)

Alias for: update

nested_under_indifferent_access ()

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)

Source

# File 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)

Source

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

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

reverse_merge (other_hash)

Source

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

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

Also aliased as: with_defaults

reverse_merge! (other_hash)

Source

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

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

Calls superclass method Hash#reverse_merge!

Also aliased as: with_defaults!

select (*args, &block)

Source

# File 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)

Source

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

Calls superclass method

slice! (*keys)

Source

# File lib/active_support/hash_with_indifferent_access.rb, line 385
def slice!(*keys)
  keys.map! { |key| convert_key(key) }
  super
end

Calls superclass method Hash#slice!

store (key, value, convert_value: true)

Source

# File 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

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.

symbolize_keys ()

Source

# File 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 ()

Source

# File 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

Convert to a regular hash with string keys.

to_options ()

Alias for: symbolize_keys

to_options! ()

Source

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

to_proc ()

Source

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

transform_keys (hash = NOT_GIVEN, &block)

Source

# File 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

Calls superclass method

transform_keys! (hash = NOT_GIVEN, &block)

Source

# File 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)

Source

# File 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)

Source

# File 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

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}

Also aliased as: regular_update, merge!

values_at (*keys)

Source

# File lib/active_support/hash_with_indifferent_access.rb, line 253
def values_at(*keys)
  keys.map! { |key| convert_key(key) }
  super
end

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

with_defaults (other_hash)

Alias for: reverse_merge

with_defaults! (other_hash)

Alias for: reverse_merge!

with_indifferent_access ()

Source

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

without (*keys)

Alias for: except