Hash
class Hash
Public Class Methods
Returns a Hash containing a collection of pairs when the key is the node name and the value is its content
xml = <<-XML <?xml version="1.0" encoding="UTF-8"?> <hash> <foo type="integer">1</foo> <bar type="integer">2</bar> </hash> XML hash = Hash.from_xml(xml) # => {"hash"=>{"foo"=>1, "bar"=>2}}
DisallowedType
is raised if the XML contains attributes with type="yaml"
or type="symbol"
. Use Hash.from_trusted_xml
to parse this XML.
Custom disallowed_types
can also be passed in the form of an array.
xml = <<-XML <?xml version="1.0" encoding="UTF-8"?> <hash> <foo type="integer">1</foo> <bar type="string">"David"</bar> </hash> XML hash = Hash.from_xml(xml, ['integer']) # => ActiveSupport::XMLConverter::DisallowedType: Disallowed type attribute: "integer"
Note that passing custom disallowed types will override the default types, which are Symbol and YAML.
# File activesupport/lib/active_support/core_ext/hash/conversions.rb, line 127 def from_xml(xml, disallowed_types = nil) ActiveSupport::XMLConverter.new(xml, disallowed_types).to_h end
Public Instance Methods
Validates all keys in a hash match *valid_keys
, raising ArgumentError
on a mismatch.
Note that keys are treated differently than HashWithIndifferentAccess, meaning that string and symbol keys will not match.
{ name: 'Rob', years: '28' }.assert_valid_keys(:name, :age) # => raises "ArgumentError: Unknown key: :years. Valid keys are: :name, :age" { name: 'Rob', age: '28' }.assert_valid_keys('name', 'age') # => raises "ArgumentError: Unknown key: :name. Valid keys are: 'name', 'age'" { name: 'Rob', age: '28' }.assert_valid_keys(:name, :age) # => passes, raises nothing
# File activesupport/lib/active_support/core_ext/hash/keys.rb, line 75 def assert_valid_keys(*valid_keys) valid_keys.flatten! each_key do |k| unless valid_keys.include?(k) raise ArgumentError.new("Unknown key: #{k.inspect}. Valid keys are: #{valid_keys.map(&:inspect).join(', ')}") end end end
Returns a hash with non nil
values.
hash = { a: true, b: false, c: nil} hash.compact # => { a: true, b: false} hash # => { a: true, b: false, c: nil} { c: nil }.compact # => {}
# File activesupport/lib/active_support/core_ext/hash/compact.rb, line 9 def compact self.select { |_, value| !value.nil? } end
Replaces current hash with non nil
values.
hash = { a: true, b: false, c: nil} hash.compact! # => { a: true, b: false} hash # => { a: true, b: false}
# File activesupport/lib/active_support/core_ext/hash/compact.rb, line 20 def compact! self.reject! { |_, value| value.nil? } end
Returns a deep copy of hash.
hash = { a: { b: 'b' } } dup = hash.deep_dup dup[:a][:c] = 'c' hash[:a][:c] # => nil dup[:a][:c] # => "c"
# File activesupport/lib/active_support/core_ext/object/deep_dup.rb, line 41 def deep_dup hash = dup each_pair do |key, value| if key.frozen? && ::String === key hash[key] = value.deep_dup else hash.delete(key) hash[key.deep_dup] = value.deep_dup end end hash end
Returns a new hash with self
and other_hash
merged recursively.
h1 = { a: true, b: { c: [1, 2, 3] } } h2 = { a: false, b: { x: [3, 4, 5] } } h1.deep_merge(h2) # => { a: false, b: { c: [1, 2, 3], x: [3, 4, 5] } }
Like with Hash#merge in the standard library, a block can be provided to merge values:
h1 = { a: 100, b: 200, c: { c1: 100 } } h2 = { b: 250, c: { c1: 200 } } h1.deep_merge(h2) { |key, this_val, other_val| this_val + other_val } # => { a: 100, b: 450, c: { c1: 300 } }
# File activesupport/lib/active_support/core_ext/hash/deep_merge.rb, line 16 def deep_merge(other_hash, &block) dup.deep_merge!(other_hash, &block) end
Same as deep_merge
, but modifies self
.
# File activesupport/lib/active_support/core_ext/hash/deep_merge.rb, line 21 def deep_merge!(other_hash, &block) other_hash.each_pair do |current_key, other_value| this_value = self[current_key] self[current_key] = if this_value.is_a?(Hash) && other_value.is_a?(Hash) this_value.deep_merge(other_value, &block) else if block_given? && key?(current_key) block.call(current_key, this_value, other_value) else other_value end end end self end
Returns a new hash with all keys converted to strings. This includes the keys from the root hash and from all nested hashes and arrays.
hash = { person: { name: 'Rob', age: '28' } } hash.deep_stringify_keys # => {"person"=>{"name"=>"Rob", "age"=>"28"}}
# File activesupport/lib/active_support/core_ext/hash/keys.rb, line 111 def deep_stringify_keys deep_transform_keys(&:to_s) end
Destructively converts all keys to strings. This includes the keys from the root hash and from all nested hashes and arrays.
# File activesupport/lib/active_support/core_ext/hash/keys.rb, line 118 def deep_stringify_keys! deep_transform_keys!(&:to_s) end
Returns a new hash with all keys converted to symbols, as long as they respond to to_sym
. This includes the keys from the root hash and from all nested hashes and arrays.
hash = { 'person' => { 'name' => 'Rob', 'age' => '28' } } hash.deep_symbolize_keys # => {:person=>{:name=>"Rob", :age=>"28"}}
# File activesupport/lib/active_support/core_ext/hash/keys.rb, line 130 def deep_symbolize_keys deep_transform_keys{ |key| key.to_sym rescue key } end
Destructively converts all keys to symbols, as long as they respond to to_sym
. This includes the keys from the root hash and from all nested hashes and arrays.
# File activesupport/lib/active_support/core_ext/hash/keys.rb, line 137 def deep_symbolize_keys! deep_transform_keys!{ |key| key.to_sym rescue key } end
Returns a new hash with all keys converted by the block operation. This includes the keys from the root hash and from all nested hashes and arrays.
hash = { person: { name: 'Rob', age: '28' } } hash.deep_transform_keys{ |key| key.to_s.upcase } # => {"PERSON"=>{"NAME"=>"Rob", "AGE"=>"28"}}
# File activesupport/lib/active_support/core_ext/hash/keys.rb, line 92 def deep_transform_keys(&block) _deep_transform_keys_in_object(self, &block) end
Destructively converts all keys by using the block operation. This includes the keys from the root hash and from all nested hashes and arrays.
# File activesupport/lib/active_support/core_ext/hash/keys.rb, line 99 def deep_transform_keys!(&block) _deep_transform_keys_in_object!(self, &block) end
Returns a hash that includes everything except given keys.
hash = { a: true, b: false, c: nil } hash.except(:c) # => { a: true, b: false } hash.except(:a, :b) # => { c: nil } hash # => { a: true, b: false, c: nil }
This is useful for limiting a set of parameters to everything but a few known toggles:
@person.update(params[:person].except(:admin))
# File activesupport/lib/active_support/core_ext/hash/except.rb, line 10 def except(*keys) dup.except!(*keys) end
Removes the given keys from hash and returns it.
hash = { a: true, b: false, c: nil } hash.except!(:c) # => { a: true, b: false } hash # => { a: true, b: false }
# File activesupport/lib/active_support/core_ext/hash/except.rb, line 18 def except!(*keys) keys.each { |key| delete(key) } self end
Removes and returns the key/value pairs matching the given keys.
{ a: 1, b: 2, c: 3, d: 4 }.extract!(:a, :b) # => {:a=>1, :b=>2} { a: 1, b: 2 }.extract!(:a, :x) # => {:a=>1}
# File activesupport/lib/active_support/core_ext/hash/slice.rb, line 45 def extract!(*keys) keys.each_with_object(self.class.new) { |key, result| result[key] = delete(key) if has_key?(key) } end
By default, only instances of Hash itself are extractable. Subclasses of Hash may implement this method and return true to declare themselves as extractable. If a Hash is extractable, Array#extract_options! pops it from the Array when it is the last element of the Array.
# File activesupport/lib/active_support/core_ext/array/extract_options.rb, line 7 def extractable_options? instance_of?(Hash) end
Called when object is nested under an object that receives with_indifferent_access. This method will be called on the current object by the enclosing object and is aliased to with_indifferent_access by default. Subclasses of Hash may overwrite this method to return self
if converting to an ActiveSupport::HashWithIndifferentAccess
would not be desirable.
b = { b: 1 } { a: b }.with_indifferent_access['a'] # calls b.nested_under_indifferent_access # => {"b"=>1}
Merges the caller into other_hash
. For example,
options = options.reverse_merge(size: 25, velocity: 10)
is equivalent to
options = { size: 25, velocity: 10 }.merge(options)
This is particularly useful for initializing an options hash with default values.
# File activesupport/lib/active_support/core_ext/hash/reverse_merge.rb, line 12 def reverse_merge(other_hash) other_hash.merge(self) end
Destructive reverse_merge
.
# File activesupport/lib/active_support/core_ext/hash/reverse_merge.rb, line 17 def reverse_merge!(other_hash) # right wins if there is no left merge!( other_hash ){|key,left,right| left } end
Slices a hash to include only the given keys. Returns a hash containing the given keys.
{ a: 1, b: 2, c: 3, d: 4 }.slice(:a, :b) # => {:a=>1, :b=>2}
This is useful for limiting an options hash to valid keys before passing to a method:
def search(criteria = {}) criteria.assert_valid_keys(:mass, :velocity, :time) end search(options.slice(:mass, :velocity, :time))
If you have an array of keys you want to limit to, you should splat them:
valid_keys = [:mass, :velocity, :time] search(options.slice(*valid_keys))
# File activesupport/lib/active_support/core_ext/hash/slice.rb, line 21 def slice(*keys) keys.map! { |key| convert_key(key) } if respond_to?(:convert_key, true) keys.each_with_object(self.class.new) { |k, hash| hash[k] = self[k] if has_key?(k) } end
Replaces the hash with only the given keys. Returns a hash containing the removed key/value pairs.
{ a: 1, b: 2, c: 3, d: 4 }.slice!(:a, :b) # => {:c=>3, :d=>4}
# File activesupport/lib/active_support/core_ext/hash/slice.rb, line 31 def slice!(*keys) keys.map! { |key| convert_key(key) } if respond_to?(:convert_key, true) omit = slice(*self.keys - keys) hash = slice(*keys) hash.default = default hash.default_proc = default_proc if default_proc replace(hash) omit end
Returns a new hash with all keys converted to strings.
hash = { name: 'Rob', age: '28' } hash.stringify_keys # => {"name"=>"Rob", "age"=>"28"}
# File activesupport/lib/active_support/core_ext/hash/keys.rb, line 37 def stringify_keys transform_keys(&:to_s) end
Destructively converts all keys to strings. Same as stringify_keys
, but modifies self
.
# File activesupport/lib/active_support/core_ext/hash/keys.rb, line 43 def stringify_keys! transform_keys!(&:to_s) end
Returns a new hash with all keys converted to symbols, as long as they respond to to_sym
.
hash = { 'name' => 'Rob', 'age' => '28' } hash.symbolize_keys # => {:name=>"Rob", :age=>"28"}
# File activesupport/lib/active_support/core_ext/hash/keys.rb, line 54 def symbolize_keys transform_keys{ |key| key.to_sym rescue key } end
Destructively converts all keys to symbols, as long as they respond to to_sym
. Same as symbolize_keys
, but modifies self
.
# File activesupport/lib/active_support/core_ext/hash/keys.rb, line 61 def symbolize_keys! transform_keys!{ |key| key.to_sym rescue key } end
Returns a string representation of the receiver suitable for use as a URL query string:
{name: 'David', nationality: 'Danish'}.to_query # => "name=David&nationality=Danish"
An optional namespace can be passed to enclose key names:
{name: 'David', nationality: 'Danish'}.to_query('user') # => "user%5Bname%5D=David&user%5Bnationality%5D=Danish"
The string pairs “key=value” that conform the query string are sorted lexicographically in ascending order.
This method is also aliased as to_param
.
# File activesupport/lib/active_support/core_ext/object/to_query.rb, line 75 def to_query(namespace = nil) collect do |key, value| unless (value.is_a?(Hash) || value.is_a?(Array)) && value.empty? value.to_query(namespace ? "#{namespace}[#{key}]" : key) end end.compact.sort! * '&' end
Returns a string containing an XML representation of its receiver:
{ foo: 1, bar: 2 }.to_xml # => # <?xml version="1.0" encoding="UTF-8"?> # <hash> # <foo type="integer">1</foo> # <bar type="integer">2</bar> # </hash>
To do so, the method loops over the pairs and builds nodes that depend on the values. Given a pair key
, value
:
-
If
value
is a hash there's a recursive call withkey
as:root
. -
If
value
is an array there's a recursive call withkey
as:root
, andkey
singularized as:children
. -
If
value
is a callable object it must expect one or two arguments. Depending on the arity, the callable is invoked with theoptions
hash as first argument withkey
as:root
, andkey
singularized as second argument. The callable can add nodes by usingoptions[:builder]
.{foo: lambda { |options, key| options[:builder].b(key) }}.to_xml # => "<b>foo</b>"
-
If
value
responds toto_xml
the method is invoked withkey
as:root
.class Foo def to_xml(options) options[:builder].bar 'fooing!' end end { foo: Foo.new }.to_xml(skip_instruct: true) # => # <hash> # <bar>fooing!</bar> # </hash>
-
Otherwise, a node with
key
as tag is created with a string representation ofvalue
as text node. Ifvalue
isnil
an attribute “nil” set to “true” is added. Unless the option:skip_types
exists and is true, an attribute “type” is added as well according to the following mapping:XML_TYPE_NAMES = { "Symbol" => "symbol", "Integer" => "integer", "BigDecimal" => "decimal", "Float" => "float", "TrueClass" => "boolean", "FalseClass" => "boolean", "Date" => "date", "DateTime" => "dateTime", "Time" => "dateTime" }
By default the root node is “hash”, but that's configurable via the :root
option.
The default XML builder is a fresh instance of Builder::XmlMarkup
. You can configure your own builder with the :builder
option. The method also accepts options like :dasherize
and friends, they are forwarded to the builder.
# File activesupport/lib/active_support/core_ext/hash/conversions.rb, line 73 def to_xml(options = {}) require 'active_support/builder' unless defined?(Builder) options = options.dup options[:indent] ||= 2 options[:root] ||= 'hash' options[:builder] ||= Builder::XmlMarkup.new(indent: options[:indent]) builder = options[:builder] builder.instruct! unless options.delete(:skip_instruct) root = ActiveSupport::XmlMini.rename_key(options[:root].to_s, options) builder.tag!(root) do each { |key, value| ActiveSupport::XmlMini.to_tag(key, value, options) } yield builder if block_given? end end
Returns a new hash with all keys converted using the block
operation.
hash = { name: 'Rob', age: '28' } hash.transform_keys { |key| key.to_s.upcase } # => {"NAME"=>"Rob", "AGE"=>"28"}
If you do not provide a block
, it will return an Enumerator for chaining with other methods:
hash.transform_keys.with_index { |k, i| [k, i].join } # => {"name0"=>"Rob", "age1"=>"28"}
# File activesupport/lib/active_support/core_ext/hash/keys.rb, line 12 def transform_keys return enum_for(:transform_keys) { size } unless block_given? result = {} each_key do |key| result[yield(key)] = self[key] end result end
Destructively converts all keys using the block
operations. Same as transform_keys
but modifies self
.
# File activesupport/lib/active_support/core_ext/hash/keys.rb, line 23 def transform_keys! return enum_for(:transform_keys!) { size } unless block_given? keys.each do |key| self[yield(key)] = delete(key) end self end
Returns a new hash with the results of running block
once for every value. The keys are unchanged.
{ a: 1, b: 2, c: 3 }.transform_values { |x| x * 2 } # => { a: 2, b: 4, c: 6 }
If you do not provide a block
, it will return an Enumerator for chaining with other methods:
{ a: 1, b: 2 }.transform_values.with_index { |v, i| [v, i].join.to_i } # => { a: 10, b: 21 }
# File activesupport/lib/active_support/core_ext/hash/transform_values.rb, line 11 def transform_values return enum_for(:transform_values) { size } unless block_given? return {} if empty? result = self.class.new each do |key, value| result[key] = yield(value) end result end
Destructively converts all values using the block
operations. Same as transform_values
but modifies self
.
# File activesupport/lib/active_support/core_ext/hash/transform_values.rb, line 23 def transform_values! return enum_for(:transform_values!) { size } unless block_given? each do |key, value| self[key] = yield(value) end end
Returns an ActiveSupport::HashWithIndifferentAccess
out of its receiver:
{ a: 1 }.with_indifferent_access['a'] # => 1
# File activesupport/lib/active_support/core_ext/hash/indifferent_access.rb, line 8 def with_indifferent_access ActiveSupport::HashWithIndifferentAccess.new(self) end
© 2004–2017 David Heinemeier Hansson
Licensed under the MIT License.