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.
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Class Public methods
[](*args) Link
new(constructor = nil) Link
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 70 def initialize(constructor = nil) if constructor.nil? super() elsif 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 else super(constructor) end end
Instance Public methods
[](key) Link
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
[]=(key, value) Link
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'.
If the value is a Hash or contains one or multiple Hashes, they will be converted to HashWithIndifferentAccess.
assoc(key) Link
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
compact() Link
deep_symbolize_keys() Link
default(key = (no_key = true)) Link
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'
delete(key) Link
Removes the specified key from the hash.
dig(*args) Link
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
dup() Link
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"
except(*keys) Link
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
extractable_options?() Link
Returns true so that Array#extract_options! finds members of this class.
fetch(key, *extras) Link
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"
fetch_values(*indices, &block) Link
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"
key?(key) Link
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
merge(*hashes, &block) Link
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.
nested_under_indifferent_access() Link
reject(*args, &block) Link
replace(other_hash) Link
Replaces the contents of this hash with other_hash.
h = { "a" => 100, "b" => 200 } h.replace({ "c" => 300, "d" => 400 }) # => {"c"=>300, "d"=>400}
reverse_merge(other_hash) Link
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}
reverse_merge!(other_hash) Link
Same semantics as reverse_merge but modifies the receiver in-place.
select(*args, &block) Link
slice(*keys) Link
slice!(*keys) Link
store(key, value, convert_value: true) Link
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'.
If the value is a Hash or contains one or multiple Hashes, they will be converted to HashWithIndifferentAccess. unless ‘convert_value: false` is set.
to_hash() Link
Convert to a regular hash with string keys.
to_options!() Link
to_proc() Link
transform_keys(hash = NOT_GIVEN, &block) Link
transform_keys!(hash = NOT_GIVEN, &block) Link
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 366 def transform_keys!(hash = NOT_GIVEN, &block) if NOT_GIVEN.equal?(hash) if block_given? replace(copy_defaults(transform_keys(&block))) else return to_enum(:transform_keys!) end else replace(copy_defaults(transform_keys(hash, &block))) end self end
transform_values(&block) Link
update(*other_hashes, &block) Link
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}
# File activesupport/lib/active_support/hash_with_indifferent_access.rb, line 148 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
values_at(*keys) Link
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"]