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.

Private Class Methods

[](*args) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 81
def self.[](*args)
  new.merge!(Hash[*args])
end
new(constructor = {}) click to toggle source
Calls superclass method
# File lib/active_support/hash_with_indifferent_access.rb, line 57
def initialize(constructor = {})
  if constructor.is_a?(Hash)
    super()
    update(constructor)
  else
    super(constructor)
  end
end
new_from_hash_copying_default(hash) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 74
def self.new_from_hash_copying_default(hash)
  hash = hash.to_hash
  new(hash).tap do |new_hash|
    new_hash.default = hash.default
  end
end

Private Instance Methods

[]=(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 94
def []=(key, value)
  regular_writer(convert_key(key), convert_value(value, for: :assignment))
end
Also aliased as: regular_writer, store
convert_key(key) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 249
def convert_key(key)
  key.kind_of?(Symbol) ? key.to_s : key
end
convert_value(value, options = {}) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 253
def convert_value(value, options = {})
  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)
    unless options[:for] == :assignment
      value = value.dup
    end
    value.map! { |e| convert_value(e, options) }
  else
    value
  end
end
deep_stringify_keys() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 224
def deep_stringify_keys; dup end
deep_stringify_keys!() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 222
def deep_stringify_keys!; self end
deep_symbolize_keys() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 228
def deep_symbolize_keys; to_hash.deep_symbolize_keys! end
default(key = nil) click to toggle source
Calls superclass method
# File lib/active_support/hash_with_indifferent_access.rb, line 66
def default(key = nil)
  if key.is_a?(Symbol) && include?(key = key.to_s)
    self[key]
  else
    super
  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 217
def delete(key)
  super(convert_key(key))
end
dup() click to toggle source

Returns an exact copy of the hash.

# File lib/active_support/hash_with_indifferent_access.rb, line 180
def dup
  self.class.new(self).tap do |new_hash|
    new_hash.default = default
  end
end
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 45
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 165
def fetch(key, *extras)
  super(convert_key(key), *extras)
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 147
def key?(key)
  super(convert_key(key))
end
Also aliased as: include?, has_key?, member?
member?(key)
Alias for: key?
merge(hash, &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 189
def merge(hash, &block)
  self.dup.update(hash, &block)
end
merge!(other_hash)
Alias for: update
nested_under_indifferent_access() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 53
def nested_under_indifferent_access
  self
end
regular_update(other_hash)
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 235
def reject(*args, &block)
  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 212
def replace(other_hash)
  super(self.class.new_from_hash_copying_default(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 199
def reverse_merge(other_hash)
  super(self.class.new_from_hash_copying_default(other_hash))
end
reverse_merge!(other_hash) click to toggle source

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

# File lib/active_support/hash_with_indifferent_access.rb, line 204
def reverse_merge!(other_hash)
  replace(reverse_merge( other_hash ))
end
select(*args, &block) click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 231
def select(*args, &block)
  dup.tap { |hash| hash.select!(*args, &block) }
end
store(key, value)
Alias for: []=
stringify_keys() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 223
def stringify_keys; dup end
stringify_keys!() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 221
def stringify_keys!; self end
symbolize_keys() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 227
def symbolize_keys; to_hash.symbolize_keys! end
to_hash() click to toggle source

Convert to a regular hash with string keys.

# File lib/active_support/hash_with_indifferent_access.rb, line 240
def to_hash
  _new_hash= {}
  each do |key, value|
    _new_hash[convert_key(key)] = convert_value(value, for: :to_hash)
  end
  Hash.new(default).merge!(_new_hash)
end
to_options!() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 229
def to_options!; self end
update(other_hash) { |convert_key(key), self, value| ... } click to toggle source

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}
Calls superclass method
# File lib/active_support/hash_with_indifferent_access.rb, line 125
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
Also aliased as: regular_update, merge!
values_at(*indices) 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"]
# File lib/active_support/hash_with_indifferent_access.rb, line 175
def values_at(*indices)
  indices.collect { |key| self[convert_key(key)] }
end
with_indifferent_access() click to toggle source
# File lib/active_support/hash_with_indifferent_access.rb, line 49
def with_indifferent_access
  dup
end