class ActiveSupport::HashWithIndifferentAccess
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.
Private Class Methods
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# File lib/active_support/hash_with_indifferent_access.rb, line 83 def self.[](*args) new.merge!(Hash[*args]) end
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# File lib/active_support/hash_with_indifferent_access.rb, line 68 def initialize(constructor = nil) if constructor.respond_to?(:to_hash) super() update(constructor) hash = constructor.is_a?(Hash) ? constructor : constructor.to_hash self.default = hash.default if hash.default self.default_proc = hash.default_proc if hash.default_proc elsif constructor.nil? super() else super(constructor) end end
Private Instance Methods
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# File lib/active_support/hash_with_indifferent_access.rb, line 166 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
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# File lib/active_support/hash_with_indifferent_access.rb, line 96 def []=(key, value) regular_writer(convert_key(key), convert_value(value, conversion: :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'
.
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# File lib/active_support/hash_with_indifferent_access.rb, line 179 def assoc(key) super(convert_key(key)) end
Same as Hash#assoc
where the key passed as argument can be either a string or a symbol:
counters = ActiveSupport::HashWithIndifferentAccess.new counters[:foo] = 1 counters.assoc('foo') # => ["foo", 1] counters.assoc(:foo) # => ["foo", 1] counters.assoc(:zoo) # => nil
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# File lib/active_support/hash_with_indifferent_access.rb, line 357 def compact dup.tap(&:compact!) end
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# File lib/active_support/hash_with_indifferent_access.rb, line 374 def convert_key(key) key.kind_of?(Symbol) ? key.name : key end
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# File lib/active_support/hash_with_indifferent_access.rb, line 383 def convert_value(value, conversion: nil) if value.is_a? Hash if conversion == :to_hash value.to_hash else value.nested_under_indifferent_access end elsif value.is_a?(Array) if conversion != :assignment || value.frozen? value = value.dup end value.map! { |e| convert_value(e, conversion: conversion) } else value end end
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# File lib/active_support/hash_with_indifferent_access.rb, line 311 def deep_stringify_keys; dup end
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# File lib/active_support/hash_with_indifferent_access.rb, line 309 def deep_stringify_keys!; self end
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# File lib/active_support/hash_with_indifferent_access.rb, line 316 def deep_symbolize_keys; to_hash.deep_symbolize_keys! end
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# File lib/active_support/hash_with_indifferent_access.rb, line 221 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'
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# File lib/active_support/hash_with_indifferent_access.rb, line 295 def delete(key) super(convert_key(key)) end
Removes the specified key from the hash.
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# File lib/active_support/hash_with_indifferent_access.rb, line 206 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
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# File lib/active_support/hash_with_indifferent_access.rb, line 256 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"
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# File lib/active_support/hash_with_indifferent_access.rb, line 303 def except(*keys) slice(*self.keys - keys.map { |key| convert_key(key) }) end
Returns a hash with indifferent access that includes everything except given keys.
hash = { a: "x", b: "y", c: 10 }.with_indifferent_access hash.except(:a, "b") # => {c: 10}.with_indifferent_access hash # => { a: "x", b: "y", c: 10 }.with_indifferent_access
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# File lib/active_support/hash_with_indifferent_access.rb, line 56 def extractable_options? true end
Returns true
so that Array#extract_options!
finds members of this class.
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# File lib/active_support/hash_with_indifferent_access.rb, line 193 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"
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# File lib/active_support/hash_with_indifferent_access.rb, line 244 def fetch_values(*indices, &block) super(*indices.map { |key| convert_key(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"
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# File lib/active_support/hash_with_indifferent_access.rb, line 149 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
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# File lib/active_support/hash_with_indifferent_access.rb, line 265 def merge(*hashes, &block) dup.update(*hashes, &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.
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# File lib/active_support/hash_with_indifferent_access.rb, line 64 def nested_under_indifferent_access self end
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# File lib/active_support/hash_with_indifferent_access.rb, line 324 def reject(*args, &block) return to_enum(:reject) unless block_given? dup.tap { |hash| hash.reject!(*args, &block) } end
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# File lib/active_support/hash_with_indifferent_access.rb, line 290 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}
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# File lib/active_support/hash_with_indifferent_access.rb, line 275 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}
Hash#reverse_merge
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# File lib/active_support/hash_with_indifferent_access.rb, line 281 def reverse_merge!(other_hash) super(self.class.new(other_hash)) end
Same semantics as reverse_merge
but modifies the receiver in-place.
Hash#reverse_merge!
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# File lib/active_support/hash_with_indifferent_access.rb, line 319 def select(*args, &block) return to_enum(:select) unless block_given? dup.tap { |hash| hash.select!(*args, &block) } end
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# File lib/active_support/hash_with_indifferent_access.rb, line 400 def set_defaults(target) if default_proc target.default_proc = default_proc.dup else target.default = default end end
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# File lib/active_support/hash_with_indifferent_access.rb, line 347 def slice(*keys) keys.map! { |key| convert_key(key) } self.class.new(super) end
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# File lib/active_support/hash_with_indifferent_access.rb, line 352 def slice!(*keys) keys.map! { |key| convert_key(key) } super end
Hash#slice!
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# File lib/active_support/hash_with_indifferent_access.rb, line 310 def stringify_keys; dup end
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# File lib/active_support/hash_with_indifferent_access.rb, line 308 def stringify_keys!; self end
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# File lib/active_support/hash_with_indifferent_access.rb, line 314 def symbolize_keys; to_hash.symbolize_keys! end
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# File lib/active_support/hash_with_indifferent_access.rb, line 362 def to_hash _new_hash = Hash.new set_defaults(_new_hash) each do |key, value| _new_hash[key] = convert_value(value, conversion: :to_hash) end _new_hash end
Convert to a regular hash with string keys.
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# File lib/active_support/hash_with_indifferent_access.rb, line 317 def to_options!; self end
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# File lib/active_support/hash_with_indifferent_access.rb, line 334 def transform_keys(*args, &block) return to_enum(:transform_keys) unless block_given? dup.tap { |hash| hash.transform_keys!(*args, &block) } end
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# File lib/active_support/hash_with_indifferent_access.rb, line 339 def transform_keys! return enum_for(:transform_keys!) { size } unless block_given? keys.each do |key| self[yield(key)] = delete(key) end self end
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# File lib/active_support/hash_with_indifferent_access.rb, line 329 def transform_values(*args, &block) return to_enum(:transform_values) unless block_given? dup.tap { |hash| hash.transform_values!(*args, &block) } end
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# File lib/active_support/hash_with_indifferent_access.rb, line 130 def update(*other_hashes, &block) if other_hashes.size == 1 update_with_single_argument(other_hashes.first, block) else other_hashes.each do |other_hash| update_with_single_argument(other_hash, block) end end self end
Updates the receiver in-place, merging in the hashes passed as arguments:
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!"} hash = ActiveSupport::HashWithIndifferentAccess.new hash.update({ "a" => 1 }, { "b" => 2 }) # => { "a" => 1, "b" => 2 }
The arguments 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 408 def update_with_single_argument(other_hash, block) if other_hash.is_a? HashWithIndifferentAccess regular_update(other_hash, &block) else other_hash.to_hash.each_pair do |key, value| if block && key?(key) value = block.call(convert_key(key), self[key], value) end regular_writer(convert_key(key), convert_value(value)) end end end
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# File lib/active_support/hash_with_indifferent_access.rb, line 231 def values_at(*keys) super(*keys.map { |key| 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"]
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# File lib/active_support/hash_with_indifferent_access.rb, line 60 def with_indifferent_access dup end