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.

Methods

[]
[]
[]=
assoc
compact
deep_symbolize_keys
default
delete
dig
dup
except
extractable_options?
fetch
fetch_values
has_key?
include?
key?
member?
merge
merge!
nested_under_indifferent_access
new
regular_update
regular_writer
reject
replace
reverse_merge
reverse_merge!
select
slice
slice!
store
symbolize_keys
to_hash
to_options
to_options!
to_proc
transform_keys
transform_keys!
transform_values
update
values_at
with_defaults
with_defaults!
with_indifferent_access
without

Class Public methods

[](*args)

📝 Source code

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

🔎 See on GitHub

new(constructor = nil)

📝 Source code

# File activesupport/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

🔎 See on GitHub

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 code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 168
    def [](key)
      super(convert_key(key))
    end

🔎 See on GitHub

[]=(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 code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 98
    def []=(key, value)
      regular_writer(convert_key(key), convert_value(value, conversion: :assignment))
    end

🔎 See on GitHub

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 code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 181
    def assoc(key)
      super(convert_key(key))
    end

🔎 See on GitHub

compact()

📝 Source code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 371
    def compact
      dup.tap(&:compact!)
    end

🔎 See on GitHub

deep_symbolize_keys()

📝 Source code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 320
    def deep_symbolize_keys; to_hash.deep_symbolize_keys! end

🔎 See on GitHub

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'

📝 Source code

# File activesupport/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

🔎 See on GitHub

delete(key)

Removes the specified key from the hash.

📝 Source code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 303
    def delete(key)
      super(convert_key(key))
    end

🔎 See on GitHub

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 code

# File activesupport/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

🔎 See on GitHub

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 code

# File activesupport/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

🔎 See on GitHub

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

Also aliased as: without

📝 Source code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 311
    def except(*keys)
      dup.except!(*keys)
    end

🔎 See on GitHub

extractable_options?()

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

📝 Source code

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

🔎 See on GitHub

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 code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 195
    def fetch(key, *extras)
      super(convert_key(key), *extras)
    end

🔎 See on GitHub

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 code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 251
    def fetch_values(*indices, &block)
      indices.map! { |key| convert_key(key) }
      super
    end

🔎 See on GitHub

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 code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 151
    def key?(key)
      super(convert_key(key))
    end

🔎 See on GitHub

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.

📝 Source code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 273
    def merge(*hashes, &block)
      dup.update(*hashes, &block)
    end

🔎 See on GitHub

merge!(*other_hashes, &block)

Alias for: update

nested_under_indifferent_access()

📝 Source code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 66
    def nested_under_indifferent_access
      self
    end

🔎 See on GitHub

regular_update(*other_hashes, &block)

Alias for: update

regular_writer(key, value)

Alias for: []=

reject(*args, &block)

📝 Source code

# File activesupport/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

🔎 See on GitHub

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 code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 298
    def replace(other_hash)
      super(self.class.new(other_hash))
    end

🔎 See on GitHub

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 code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 283
    def reverse_merge(other_hash)
      super(self.class.new(other_hash))
    end

🔎 See on GitHub

reverse_merge!(other_hash)

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

Also aliased as: with_defaults!

📝 Source code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 289
    def reverse_merge!(other_hash)
      super(self.class.new(other_hash))
    end

🔎 See on GitHub

select(*args, &block)

📝 Source code

# File activesupport/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

🔎 See on GitHub

slice(*keys)

📝 Source code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 361
    def slice(*keys)
      keys.map! { |key| convert_key(key) }
      self.class.new(super)
    end

🔎 See on GitHub

slice!(*keys)

📝 Source code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 366
    def slice!(*keys)
      keys.map! { |key| convert_key(key) }
      super
    end

🔎 See on GitHub

store(key, value)

Alias for: []=

symbolize_keys()

Also aliased as: to_options

📝 Source code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 318
    def symbolize_keys; to_hash.symbolize_keys! end

🔎 See on GitHub

to_hash()

Convert to a regular hash with string keys.

📝 Source code

# File activesupport/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

🔎 See on GitHub

to_options()

Alias for: symbolize_keys

to_options!()

📝 Source code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 321
    def to_options!; self end

🔎 See on GitHub

to_proc()

📝 Source code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 383
    def to_proc
      proc { |key| self[key] }
    end

🔎 See on GitHub

transform_keys(hash = NOT_GIVEN, &block)

📝 Source code

# File activesupport/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

🔎 See on GitHub

transform_keys!(hash = NOT_GIVEN, &block)

📝 Source code

# File activesupport/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

🔎 See on GitHub

transform_values(&block)

📝 Source code

# File activesupport/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

🔎 See on GitHub

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}

Also aliased as: regular_update, merge!

📝 Source code

# File activesupport/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

🔎 See on GitHub

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 code

# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 237
    def values_at(*keys)
      keys.map! { |key| convert_key(key) }
      super
    end

🔎 See on GitHub

with_defaults(other_hash)

Alias for: reverse_merge

with_defaults!(other_hash)

Alias for: reverse_merge!

with_indifferent_access()

📝 Source code

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

🔎 See on GitHub

without(*keys)

Alias for: except

ActiveSupport::HashWithIndifferentAccess < Hash

Hash With Indifferent Access

Methods

Class Public methods

[](*args)

new(constructor = nil)

Instance Public methods

[](key)

[]=(key, value)

assoc(key)

compact()

deep_symbolize_keys()

default(key = (no_key = true))

delete(key)

dig(*args)

dup()

except(*keys)

extractable_options?()

fetch(key, *extras)

fetch_values(*indices, &block)

has_key?(key)

include?(key)

key?(key)

member?(key)

merge(*hashes, &block)

merge!(*other_hashes, &block)

nested_under_indifferent_access()

regular_update(*other_hashes, &block)

regular_writer(key, value)

reject(*args, &block)

replace(other_hash)

reverse_merge(other_hash)

reverse_merge!(other_hash)

select(*args, &block)

slice(*keys)

slice!(*keys)

store(key, value)

symbolize_keys()

to_hash()

to_options()

to_options!()

to_proc()

transform_keys(hash = NOT_GIVEN, &block)

transform_keys!(hash = NOT_GIVEN, &block)

transform_values(&block)

update(*other_hashes, &block)

values_at(*keys)

with_defaults(other_hash)

with_defaults!(other_hash)

with_indifferent_access()

without(*keys)