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, #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_param, #to_query, #to_xml, #transform_keys, #transform_keys!

Constructor Details

- (HashWithIndifferentAccess) initialize(constructor = {})



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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 57

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

Class Method Details

+ (Object) [](*args)



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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 81

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

+ (Object) new_from_hash_copying_default(hash)



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# File 'activesupport/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

Instance Method Details

- (Object) []=(key, value) 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 94

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

- (Object) deep_stringify_keys



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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 224

def deep_stringify_keys; dup end

- (Object) deep_stringify_keys!



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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 222

def deep_stringify_keys!; self end

- (Object) deep_symbolize_keys



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

def deep_symbolize_keys; to_hash.deep_symbolize_keys! end

- (Object) default(key = nil)



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# File 'activesupport/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

- (Object) delete(key)

Removes the specified key from the hash.



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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 217

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

- (Object) dup

Returns an exact copy of the hash.



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# File 'activesupport/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

- (Boolean) extractable_options?

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 45

def extractable_options?
  true
end

- (Object) 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"


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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 165

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

- (Boolean) key?(key) 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 147

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

- (Object) 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.



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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 189

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

- (Object) nested_under_indifferent_access



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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 53

def nested_under_indifferent_access
  self
end

- (Object) regular_update



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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 86

alias_method :regular_update, :update

- (Object) regular_writer



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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 85

alias_method :regular_writer, :[]=

- (Object) reject(*args, &block)



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

def reject(*args, &block)
  dup.tap { |hash| hash.reject!(*args, &block) }
end

- (Object) 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}


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# File 'activesupport/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

- (Object) 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}


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# File 'activesupport/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

- (Object) reverse_merge!(other_hash)

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 204

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

- (Object) select(*args, &block)



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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 231

def select(*args, &block)
  dup.tap { |hash| hash.select!(*args, &block) }
end

- (Object) stringify_keys



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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 223

def stringify_keys; dup end

- (Object) stringify_keys!



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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 221

def stringify_keys!; self end

- (Object) symbolize_keys



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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 227

def symbolize_keys; to_hash.symbolize_keys! end

- (Object) to_hash

Convert to a regular hash with string keys.



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# File 'activesupport/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

- (Object) to_options!



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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 229

def to_options!; self end

- (Object) update(other_hash) 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 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

- (Object) values_at(*indices)

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 175

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

- (Object) with_indifferent_access



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# File 'activesupport/lib/active_support/hash_with_indifferent_access.rb', line 49

def with_indifferent_access
  dup
end