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.
Private Class Methods
# File lib/active_support/hash_with_indifferent_access.rb, line 81 def self.[](*args) new.merge!(Hash[*args]) end
# File lib/active_support/hash_with_indifferent_access.rb, line 57 def initialize(constructor = {}) if constructor.is_a?(Hash) super() update(constructor) else super(constructor) end end
# File lib/active_support/hash_with_indifferent_access.rb, line 74 def self.new_from_hash_copying_default(hash) hash = hash.to_hash new(hash).tap do |new_hash| new_hash.default = hash.default end end
Private Instance Methods
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'+.
# File lib/active_support/hash_with_indifferent_access.rb, line 94 def []=(key, value) regular_writer(convert_key(key), convert_value(value, for: :assignment)) end
# File lib/active_support/hash_with_indifferent_access.rb, line 249 def convert_key(key) key.kind_of?(Symbol) ? key.to_s : key end
# File lib/active_support/hash_with_indifferent_access.rb, line 253 def convert_value(value, options = {}) 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) unless options[:for] == :assignment value = value.dup end value.map! { |e| convert_value(e, options) } else value end end
# File lib/active_support/hash_with_indifferent_access.rb, line 224 def deep_stringify_keys; dup end
# File lib/active_support/hash_with_indifferent_access.rb, line 222 def deep_stringify_keys!; self end
# File lib/active_support/hash_with_indifferent_access.rb, line 228 def deep_symbolize_keys; to_hash.deep_symbolize_keys! end
# File lib/active_support/hash_with_indifferent_access.rb, line 66 def default(key = nil) if key.is_a?(Symbol) && include?(key = key.to_s) self[key] else super end end
Removes the specified key from the hash.
# File lib/active_support/hash_with_indifferent_access.rb, line 217 def delete(key) super(convert_key(key)) end
Returns an exact copy of the hash.
# File lib/active_support/hash_with_indifferent_access.rb, line 180 def dup self.class.new(self).tap do |new_hash| new_hash.default = default end end
Returns true
so that Array#extract_options!
finds
members of this class.
# File lib/active_support/hash_with_indifferent_access.rb, line 45 def extractable_options? true 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"
# File lib/active_support/hash_with_indifferent_access.rb, line 165 def fetch(key, *extras) super(convert_key(key), *extras) 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
# File lib/active_support/hash_with_indifferent_access.rb, line 147 def key?(key) super(convert_key(key)) 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.
# File lib/active_support/hash_with_indifferent_access.rb, line 189 def merge(hash, &block) self.dup.update(hash, &block) end
# File lib/active_support/hash_with_indifferent_access.rb, line 53 def nested_under_indifferent_access self end
# File lib/active_support/hash_with_indifferent_access.rb, line 235 def reject(*args, &block) dup.tap { |hash| hash.reject!(*args, &block) } 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}
# File lib/active_support/hash_with_indifferent_access.rb, line 212 def replace(other_hash) super(self.class.new_from_hash_copying_default(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}
# File lib/active_support/hash_with_indifferent_access.rb, line 199 def reverse_merge(other_hash) super(self.class.new_from_hash_copying_default(other_hash)) end
Same semantics as reverse_merge
but modifies the receiver
in-place.
# File lib/active_support/hash_with_indifferent_access.rb, line 204 def reverse_merge!(other_hash) replace(reverse_merge( other_hash )) end
# File lib/active_support/hash_with_indifferent_access.rb, line 231 def select(*args, &block) dup.tap { |hash| hash.select!(*args, &block) } end
# File lib/active_support/hash_with_indifferent_access.rb, line 223 def stringify_keys; dup end
# File lib/active_support/hash_with_indifferent_access.rb, line 221 def stringify_keys!; self end
# File lib/active_support/hash_with_indifferent_access.rb, line 227 def symbolize_keys; to_hash.symbolize_keys! end
Convert to a regular hash with string keys.
# File lib/active_support/hash_with_indifferent_access.rb, line 240 def to_hash _new_hash= {} each do |key, value| _new_hash[convert_key(key)] = convert_value(value, for: :to_hash) end Hash.new(default).merge!(_new_hash) end
# File lib/active_support/hash_with_indifferent_access.rb, line 229 def to_options!; self 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}
# File lib/active_support/hash_with_indifferent_access.rb, line 125 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
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"]
# File lib/active_support/hash_with_indifferent_access.rb, line 175 def values_at(*indices) indices.collect { |key| self[convert_key(key)] } end
# File lib/active_support/hash_with_indifferent_access.rb, line 49 def with_indifferent_access dup end