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.

Direct Known Subclasses

ActionController::Parameters

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Hash

#as_json, #assert_valid_keys, #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!

Constructor Details

#initialize(constructor = {}) ⇒ HashWithIndifferentAccess

Returns a new instance of HashWithIndifferentAccess.


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 58

def initialize(constructor = {})
  if constructor.respond_to?(:to_hash)
    super()
    update(constructor)
  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 83

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 75

def self.new_from_hash_copying_default(hash)
  hash = hash.to_hash
  new(hash).tap do |new_hash|
    new_hash.default = hash.default
    new_hash.default_proc = hash.default_proc if hash.default_proc
  end
end

Instance Method Details

#[]=(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 96

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

#compactObject


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

def compact
  dup.tap(&:compact!)
end

#deep_stringify_keysObject


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 233

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 231

def deep_stringify_keys!; self end

#deep_symbolize_keysObject


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 237

def deep_symbolize_keys; to_hash.deep_symbolize_keys! end

#default(key = nil) ⇒ Object


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 67

def default(key = nil)
  if key.is_a?(Symbol) && include?(key = key.to_s)
    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 226

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 189

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.

Returns:

  • (Boolean)

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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 46

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 167

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

Returns:

  • (Boolean)

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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 149

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 198

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 54

def nested_under_indifferent_access
  self
end

#regular_updateObject


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 88

alias_method :regular_update, :update

#regular_writerObject


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

alias_method :regular_writer, :[]=

#reject(*args, &block) ⇒ Object


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 244

def reject(*args, &block)
  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 221

def replace(other_hash)
  super(self.class.new_from_hash_copying_default(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 208

def reverse_merge(other_hash)
  super(self.class.new_from_hash_copying_default(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 213

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 240

def select(*args, &block)
  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 232

def stringify_keys; dup end

#stringify_keys!Object


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 230

def stringify_keys!; self end

#symbolize_keysObject


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 236

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 258

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 238

def to_options!; self end

#transform_values(*args, &block) ⇒ Object


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

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) ⇒ 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 127

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 177

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 50

def with_indifferent_access
  dup
end