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/Ruby on Rails 5.2

class ActiveSupport::HashWithIndifferentAccess

Parent:
Hash

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.

Public Class Methods

[](*args) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 79
def self.[](*args)
  new.merge!(Hash[*args])
end
new(constructor = {}) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 66
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
Calls superclass method

Public Instance Methods

[](key) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 162
def [](key)
  super(convert_key(key))
end

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
Calls superclass method
[]=(key, value) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 92
def []=(key, value)
  regular_writer(convert_key(key), convert_value(value, for: :assignment))
end

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
compact() Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 333
def compact
  dup.tap(&:compact!)
end
deep_stringify_keys() Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 287
def deep_stringify_keys; dup end
deep_stringify_keys!() Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 285
def deep_stringify_keys!; self end
deep_symbolize_keys() Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 292
def deep_symbolize_keys; to_hash.deep_symbolize_keys! end
default(*args) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 206
def default(*args)
  super(*args.map { |arg| convert_key(arg) })
end

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'
Calls superclass method
delete(key) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 280
def delete(key)
  super(convert_key(key))
end

Removes the specified key from the hash.

Calls superclass method
dig(*args) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 190
def dig(*args)
  args[0] = convert_key(args[0]) if args.size > 0
  super(*args)
end

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
Calls superclass method
dup() Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 241
def dup
  self.class.new(self).tap do |new_hash|
    set_defaults(new_hash)
  end
end

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"
extractable_options?() Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 54
def extractable_options?
  true
end

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

fetch(key, *extras) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 176
def fetch(key, *extras)
  super(convert_key(key), *extras)
end

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
fetch_values(*indices, &block) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 229
def fetch_values(*indices, &block)
  indices.collect { |key| fetch(key, &block) }
end

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"
has_key?(key)
Alias for: key?
include?(key)
Alias for: key?
key?(key) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 145
def key?(key)
  super(convert_key(key))
end

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
Also aliased as: include?, has_key?, member?
member?(key)
Alias for: key?
merge(hash, &block) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 250
def merge(hash, &block)
  dup.update(hash, &block)
end

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.

merge!(other_hash)
Alias for: update
nested_under_indifferent_access() Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 62
def nested_under_indifferent_access
  self
end
regular_update(other_hash)
Alias for: update
regular_writer(key, value)
Alias for: []=
reject(*args, &block) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 300
def reject(*args, &block)
  return to_enum(:reject) unless block_given?
  dup.tap { |hash| hash.reject!(*args, &block) }
end
replace(other_hash) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 275
def replace(other_hash)
  super(self.class.new(other_hash))
end

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
reverse_merge(other_hash) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 260
def reverse_merge(other_hash)
  super(self.class.new(other_hash))
end

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
Also aliased as: with_defaults
reverse_merge!(other_hash) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 266
def reverse_merge!(other_hash)
  super(self.class.new(other_hash))
end

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

Calls superclass method Hash#reverse_merge!
Also aliased as: with_defaults!
select(*args, &block) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 295
def select(*args, &block)
  return to_enum(:select) unless block_given?
  dup.tap { |hash| hash.select!(*args, &block) }
end
slice(*keys) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 323
def slice(*keys)
  keys.map! { |key| convert_key(key) }
  self.class.new(super)
end
Calls superclass method Hash#slice
slice!(*keys) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 328
def slice!(*keys)
  keys.map! { |key| convert_key(key) }
  super
end
Calls superclass method Hash#slice!
store(key, value)
Alias for: []=
stringify_keys() Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 286
def stringify_keys; dup end
stringify_keys!() Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 284
def stringify_keys!; self end
symbolize_keys() Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 290
def symbolize_keys; to_hash.symbolize_keys! end
Also aliased as: to_options
to_hash() Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 338
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

Convert to a regular hash with string keys.

to_options()
Alias for: symbolize_keys
to_options!() Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 293
def to_options!; self end
transform_keys(*args, &block) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 310
def transform_keys(*args, &block)
  return to_enum(:transform_keys) unless block_given?
  dup.tap { |hash| hash.transform_keys!(*args, &block) }
end
transform_keys!() { |key| ... } Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 315
def transform_keys!
  return enum_for(:transform_keys!) { size } unless block_given?
  keys.each do |key|
    self[yield(key)] = delete(key)
  end
  self
end
transform_values(*args, &block) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 305
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) { |convert_key(key), self, value| ... } Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 123
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

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
Also aliased as: regular_update, merge!
values_at(*indices) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 216
def values_at(*indices)
  indices.collect { |key| self[convert_key(key)] }
end

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"]
with_defaults(other_hash)
Alias for: reverse_merge
with_defaults!(other_hash)
Alias for: reverse_merge!
with_indifferent_access() Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 58
def with_indifferent_access
  dup
end

Private Instance Methods

convert_key(key) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 349
def convert_key(key) # :doc:
  key.kind_of?(Symbol) ? key.to_s : key
end
convert_value(value, options = {}) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 353
def convert_value(value, options = {}) # :doc:
  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)
    if options[:for] != :assignment || value.frozen?
      value = value.dup
    end
    value.map! { |e| convert_value(e, options) }
  else
    value
  end
end
set_defaults(target) Show source
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 370
def set_defaults(target) # :doc:
  if default_proc
    target.default_proc = default_proc.dup
  else
    target.default = default
  end
end

© 2004–2018 David Heinemeier Hansson
Licensed under the MIT License.