Class: ActiveSupport::HashWithIndifferentAccess

Inherits:
Hash
  • Object
show all
Defined in:
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!, #deep_dup, #deep_merge, #deep_merge!, #deep_symbolize_keys!, #deep_transform_keys, #deep_transform_keys!, #except, #except!, #extract!, from_trusted_xml, from_xml, #symbolize_keys!, #to_query, #to_xml, #transform_values!

Constructor Details

#initialize(constructor = {}) ⇒ HashWithIndifferentAccess

Returns a new instance of HashWithIndifferentAccess.


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# File '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

Class Method Details

.[](*args) ⇒ Object


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 79

def self.[](*args)
  new.merge!(Hash[*args])
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 'lib/active_support/hash_with_indifferent_access.rb', line 162

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 'lib/active_support/hash_with_indifferent_access.rb', line 92

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

#compactObject


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 332

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

#deep_stringify_keysObject


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 287

def deep_stringify_keys; dup end

#deep_stringify_keys!Object


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 285

def deep_stringify_keys!; self end

#deep_symbolize_keysObject


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 291

def deep_symbolize_keys; to_hash.deep_symbolize_keys! end

#default(*args) ⇒ Object

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'

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# File 'lib/active_support/hash_with_indifferent_access.rb', line 206

def default(*args)
  super(*args.map { |arg| convert_key(arg) })
end

#delete(key) ⇒ Object

Removes the specified key from the hash.


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 280

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

#dig(*args) ⇒ Object

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

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# File '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

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

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# File '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

#extractable_options?Boolean

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

Returns:

  • (Boolean)

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# File 'lib/active_support/hash_with_indifferent_access.rb', line 54

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 'lib/active_support/hash_with_indifferent_access.rb', line 176

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

#fetch_values(*indices, &block) ⇒ Object

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"

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

def fetch_values(*indices, &block)
  indices.collect { |key| fetch(key, &block) }
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 'lib/active_support/hash_with_indifferent_access.rb', line 145

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 'lib/active_support/hash_with_indifferent_access.rb', line 250

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

#nested_under_indifferent_accessObject


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 62

def nested_under_indifferent_access
  self
end

#regular_updateObject


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 84

alias_method :regular_update, :update

#regular_writerObject


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 83

alias_method :regular_writer, :[]=

#reject(*args, &block) ⇒ Object


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 299

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 'lib/active_support/hash_with_indifferent_access.rb', line 275

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

#reverse_merge(other_hash) ⇒ Object Also known as: with_defaults

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 'lib/active_support/hash_with_indifferent_access.rb', line 260

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

#reverse_merge!(other_hash) ⇒ Object Also known as: with_defaults!

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


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 266

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

#select(*args, &block) ⇒ Object


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 294

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

#slice(*keys) ⇒ Object


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 322

def slice(*keys)
  keys.map! { |key| convert_key(key) }
  self.class.new(super)
end

#slice!(*keys) ⇒ Object


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 327

def slice!(*keys)
  keys.map! { |key| convert_key(key) }
  super
end

#stringify_keysObject


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 286

def stringify_keys; dup end

#stringify_keys!Object


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 284

def stringify_keys!; self end

#symbolize_keysObject


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 290

def symbolize_keys; to_hash.symbolize_keys! end

#to_hashObject

Convert to a regular hash with string keys.


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 337

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 'lib/active_support/hash_with_indifferent_access.rb', line 292

def to_options!; self end

#transform_keys(*args, &block) ⇒ Object


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 309

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

#transform_keys!Object


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 314

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) ⇒ Object


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# File 'lib/active_support/hash_with_indifferent_access.rb', line 304

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 '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

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

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

#with_indifferent_accessObject


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

def with_indifferent_access
  dup
end