Class: ActiveSupport::HashWithIndifferentAccess

Inherits:
Hash
  • Object
show all
Defined in:
activesupport/lib/active_support/hash_with_indifferent_access.rb

Overview

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.

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Hash

#as_json, #assert_valid_keys, #compact, #compact!, #deep_dup, #deep_merge, #deep_merge!, #deep_symbolize_keys!, #deep_transform_keys, #deep_transform_keys!, #except, #except!, #extract!, from_trusted_xml, from_xml, #slice, #slice!, #symbolize_keys!, #to_query, #to_xml, #transform_keys, #transform_keys!, #transform_values, #transform_values!

Constructor Details

#initialize(constructor = {}) ⇒ HashWithIndifferentAccess


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 64

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

Class Method Details

.[](*args) ⇒ Object


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 96

def self.[](*args)
  new.merge!(Hash[*args])
end

.new_from_hash_copying_default(hash) ⇒ Object


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 87

def self.new_from_hash_copying_default(hash)
  ActiveSupport::Deprecation.warn(<<-MSG.squish)
    `ActiveSupport::HashWithIndifferentAccess.new_from_hash_copying_default`
    has been deprecated, and will be removed in Rails 5.1. The behavior of
    this method is now identical to the behavior of `.new`.
  MSG
  new(hash)
end

Instance Method Details

#[](key) ⇒ Object

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

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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 180

def [](key)
  super(convert_key(key))
end

#[]=(key, value) ⇒ Object Also known as: store

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'.


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 109

def []=(key, value)
  regular_writer(convert_key(key), convert_value(value, for: :assignment))
end

#deep_stringify_keysObject


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 260

def deep_stringify_keys; dup end

#deep_stringify_keys!Object


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 258

def deep_stringify_keys!; self end

#deep_symbolize_keysObject


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 264

def deep_symbolize_keys; to_hash.deep_symbolize_keys! end

#default(*args) ⇒ Object


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 77

def default(*args)
  arg_key = args.first

  if include?(key = convert_key(arg_key))
    self[key]
  else
    super
  end
end

#delete(key) ⇒ Object

Removes the specified key from the hash.


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 253

def delete(key)
  super(convert_key(key))
end

#dupObject

Returns a shallow copy of the hash.

hash = ActiveSupport::HashWithIndifferentAccess.new({ a: { b: 'b' } })
dup  = hash.dup
dup[:a][:c] = 'c'

hash[:a][:c] # => nil
dup[:a][:c]  # => "c"

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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 216

def dup
  self.class.new(self).tap do |new_hash|
    set_defaults(new_hash)
  end
end

#extractable_options?Boolean

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


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 52

def extractable_options?
  true
end

#fetch(key, *extras) ⇒ Object

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"

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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 194

def fetch(key, *extras)
  super(convert_key(key), *extras)
end

#key?(key) ⇒ Boolean Also known as: include?, has_key?, member?

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

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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 162

def key?(key)
  super(convert_key(key))
end

#merge(hash, &block) ⇒ Object

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.


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 225

def merge(hash, &block)
  self.dup.update(hash, &block)
end

#nested_under_indifferent_accessObject


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 60

def nested_under_indifferent_access
  self
end

#regular_updateObject


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 101

alias_method :regular_update, :update

#regular_writerObject


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 100

alias_method :regular_writer, :[]=

#reject(*args, &block) ⇒ Object


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 272

def reject(*args, &block)
  return to_enum(:reject) unless block_given?
  dup.tap { |hash| hash.reject!(*args, &block) }
end

#replace(other_hash) ⇒ Object

Replaces the contents of this hash with other_hash.

h = { "a" => 100, "b" => 200 }
h.replace({ "c" => 300, "d" => 400 }) # => {"c"=>300, "d"=>400}

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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 248

def replace(other_hash)
  super(self.class.new(other_hash))
end

#reverse_merge(other_hash) ⇒ Object

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}

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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 235

def reverse_merge(other_hash)
  super(self.class.new(other_hash))
end

#reverse_merge!(other_hash) ⇒ Object

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


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 240

def reverse_merge!(other_hash)
  replace(reverse_merge( other_hash ))
end

#select(*args, &block) ⇒ Object


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 267

def select(*args, &block)
  return to_enum(:select) unless block_given?
  dup.tap { |hash| hash.select!(*args, &block) }
end

#stringify_keysObject


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 259

def stringify_keys; dup end

#stringify_keys!Object


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 257

def stringify_keys!; self end

#symbolize_keysObject


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 263

def symbolize_keys; to_hash.symbolize_keys! end

#to_hashObject

Convert to a regular hash with string keys.


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 278

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!Object


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 265

def to_options!; self end

#update(other_hash) ⇒ Object Also known as: merge!

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}

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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 140

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(*indices) ⇒ Object

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"]

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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 204

def values_at(*indices)
  indices.collect { |key| self[convert_key(key)] }
end

#with_indifferent_accessObject


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 56

def with_indifferent_access
  dup
end