class ActiveSupport::HashWithIndifferentAccess
Hash With Indifferent Access¶ ↑
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
Source
# File lib/active_support/hash_with_indifferent_access.rb, line 85 def self.[](*args) new.merge!(Hash[*args]) end
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# File lib/active_support/hash_with_indifferent_access.rb, line 70 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
Source
# File lib/active_support/hash_with_indifferent_access.rb, line 168 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 98 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'
.
Source
# File lib/active_support/hash_with_indifferent_access.rb, line 181 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 371 def compact dup.tap(&:compact!) end
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# File lib/active_support/hash_with_indifferent_access.rb, line 388 def convert_key(key) Symbol === key ? key.name : key end
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# File lib/active_support/hash_with_indifferent_access.rb, line 392 def convert_value(value, conversion: nil) if value.is_a? Hash value.nested_under_indifferent_access 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 405 def convert_value_to_hash(value) if value.is_a? Hash value.to_hash elsif value.is_a?(Array) value.map { |e| convert_value_to_hash(e) } else value end end
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# File lib/active_support/hash_with_indifferent_access.rb, line 320 def deep_symbolize_keys; to_hash.deep_symbolize_keys! end
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# File lib/active_support/hash_with_indifferent_access.rb, line 223 def default(key = (no_key = true)) if no_key super() else super(convert_key(key)) end 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 303 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 208 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 264 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 311 def except(*keys) dup.except!(*keys) 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 58 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 195 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 251 def fetch_values(*indices, &block) indices.map! { |key| convert_key(key) } super 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 151 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 273 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 66 def nested_under_indifferent_access self end
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# File lib/active_support/hash_with_indifferent_access.rb, line 328 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 298 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 283 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 289 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 323 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 416 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 361 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 366 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 318 def symbolize_keys; to_hash.symbolize_keys! end
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# File lib/active_support/hash_with_indifferent_access.rb, line 376 def to_hash copy = Hash[self] copy.transform_values! { |v| convert_value_to_hash(v) } set_defaults(copy) copy end
Convert to a regular hash with string keys.
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# File lib/active_support/hash_with_indifferent_access.rb, line 321 def to_options!; self end
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# File lib/active_support/hash_with_indifferent_access.rb, line 383 def to_proc proc { |key| self[key] } end
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# File lib/active_support/hash_with_indifferent_access.rb, line 340 def transform_keys(hash = NOT_GIVEN, &block) return to_enum(:transform_keys) if NOT_GIVEN.equal?(hash) && !block_given? dup.tap { |h| h.transform_keys!(hash, &block) } end
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# File lib/active_support/hash_with_indifferent_access.rb, line 345 def transform_keys!(hash = NOT_GIVEN, &block) return to_enum(:transform_keys!) if NOT_GIVEN.equal?(hash) && !block_given? if hash.nil? super elsif NOT_GIVEN.equal?(hash) keys.each { |key| self[yield(key)] = delete(key) } elsif block_given? keys.each { |key| self[hash[key] || yield(key)] = delete(key) } else keys.each { |key| self[hash[key] || key] = delete(key) } end self end
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# File lib/active_support/hash_with_indifferent_access.rb, line 333 def transform_values(&block) return to_enum(:transform_values) unless block_given? dup.tap { |hash| hash.transform_values!(&block) } end
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# File lib/active_support/hash_with_indifferent_access.rb, line 132 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 424 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 237 def values_at(*keys) keys.map! { |key| convert_key(key) } super 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 62 def with_indifferent_access dup end