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.

Methods

Class Public methods

[](*args)

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 80
def self.[](*args)
  new.merge!(Hash[*args])
end

new(constructor = {})

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 67
def initialize(constructor = {})
  if constructor.respond_to?(:to_hash)
    super()
    update(constructor)

    hash = 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

Instance Public 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: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 163
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'.

Also aliased as: regular_writer, store

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 93
def []=(key, value)
  regular_writer(convert_key(key), convert_value(value, for: :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: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 176
def assoc(key)
  super(convert_key(key))
end

compact()

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 350
def compact
  dup.tap(&:compact!)
end

deep_stringify_keys()

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 304
def deep_stringify_keys; dup end

deep_stringify_keys!()

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 302
def deep_stringify_keys!; self end

deep_symbolize_keys()

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 309
def deep_symbolize_keys; to_hash.deep_symbolize_keys! end

default(*args)

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: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 218
def default(*args)
  super(*args.map { |arg| convert_key(arg) })
end

delete(key)

Removes the specified key from the hash.

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 292
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: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 203
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: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 253
def dup
  self.class.new(self).tap do |new_hash|
    set_defaults(new_hash)
  end
end

except(*keys)

Also aliased as: without

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 296
def except(*keys)
  slice(*self.keys - keys.map { |key| convert_key(key) })
end

extractable_options?()

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

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 55
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: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 190
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: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 241
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)

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

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 146
def key?(key)
  super(convert_key(key))
end

member?(key)

Alias for: key?

merge(hash, &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: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 262
def merge(hash, &block)
  dup.update(hash, &block)
end

merge!(other_hash)

Alias for: update

nested_under_indifferent_access()

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 63
def nested_under_indifferent_access
  self
end

regular_update(other_hash)

Alias for: update

regular_writer(key, value)

Alias for: []=

reject(*args, &block)

Source: 

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

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 287
def replace(other_hash)
  super(self.class.new(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}
Also aliased as: with_defaults

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 272
def reverse_merge(other_hash)
  super(self.class.new(other_hash))
end

reverse_merge!(other_hash)

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

Also aliased as: with_defaults!

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 278
def reverse_merge!(other_hash)
  super(self.class.new(other_hash))
end

select(*args, &block)

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 312
def select(*args, &block)
  return to_enum(:select) unless block_given?
  dup.tap { |hash| hash.select!(*args, &block) }
end

slice(*keys)

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 340
def slice(*keys)
  keys.map! { |key| convert_key(key) }
  self.class.new(super)
end

slice!(*keys)

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 345
def slice!(*keys)
  keys.map! { |key| convert_key(key) }
  super
end

store(key, value)

Alias for: []=

stringify_keys()

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 303
def stringify_keys; dup end

stringify_keys!()

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 301
def stringify_keys!; self end

symbolize_keys()

Also aliased as: to_options

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 307
def symbolize_keys; to_hash.symbolize_keys! end

to_hash()

Convert to a regular hash with string keys.

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 355
def to_hash
  _new_hash = Hash.new
  set_defaults(_new_hash)

  each do |key, value|
    _new_hash[key] = convert_value(value, for: :to_hash)
  end
  _new_hash
end

to_options()

Alias for: symbolize_keys

to_options!()

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 310
def to_options!; self end

transform_keys(*args, &block)

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 327
def transform_keys(*args, &block)
  return to_enum(:transform_keys) unless block_given?
  dup.tap { |hash| hash.transform_keys!(*args, &block) }
end

transform_keys!()

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 332
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)

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 322
def transform_values(*args, &block)
  return to_enum(:transform_values) unless block_given?
  dup.tap { |hash| hash.transform_values!(*args, &block) }
end

update(other_hash)

Updates the receiver in-place, merging in the hash passed as argument:

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!"}

The argument 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!

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 124
def update(other_hash)
  if other_hash.is_a? HashWithIndifferentAccess
    super(other_hash)
  else
    other_hash.to_hash.each_pair do |key, value|
      if block_given? && key?(key)
        value = yield(convert_key(key), self[key], value)
      end
      regular_writer(convert_key(key), convert_value(value))
    end
    self
  end
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: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 228
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()

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 59
def with_indifferent_access
  dup
end

without(*keys)

Alias for: except

Instance Private methods

convert_key(key)

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 366
def convert_key(key) # :doc:
  key.kind_of?(Symbol) ? key.to_s : key
end

convert_value(value, options = {})

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 370
def convert_value(value, options = {}) # :doc:
  if value.is_a? Hash
    if options[:for] == :to_hash
      value.to_hash
    else
      value.nested_under_indifferent_access
    end
  elsif value.is_a?(Array)
    if options[:for] != :assignment || value.frozen?
      value = value.dup
    end
    value.map! { |e| convert_value(e, options) }
  else
    value
  end
end

set_defaults(target)

Source: 

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 387
def set_defaults(target) # :doc:
  if default_proc
    target.default_proc = default_proc.dup
  else
    target.default = default
  end
end