Methods
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Constants
DISALLOWED_XML_TYPES = %w(symbol yaml)
 
Instance Public methods
assert_valid_keys(*valid_keys)

Validate all keys in a hash match *valid keys, raising ArgumentError on a mismatch. Note that keys are NOT treated indifferently, meaning if you use strings for keys but assert symbols as keys, this will fail.

Examples

{ :name => "Rob", :years => "28" }.assert_valid_keys(:name, :age) # => raises "ArgumentError: Unknown key: years"
{ :name => "Rob", :age => "28" }.assert_valid_keys("name", "age") # => raises "ArgumentError: Unknown key: name"
{ :name => "Rob", :age => "28" }.assert_valid_keys(:name, :age) # => passes, raises nothing
# File activesupport/lib/active_support/core_ext/hash/keys.rb, line 48
def assert_valid_keys(*valid_keys)
  valid_keys.flatten!
  each_key do |k|
    raise(ArgumentError, "Unknown key: #{k}") unless valid_keys.include?(k)
  end
end
deep_dup()

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/hash/deep_dup.rb, line 10
def deep_dup
  duplicate = self.dup
  duplicate.each_pair do |k,v|
    tv = duplicate[k]
    duplicate[k] = tv.is_a?(Hash) && v.is_a?(Hash) ? tv.deep_dup : v
  end
  duplicate
end
deep_merge(other_hash)

Returns a new hash with selfand other_hash merged recursively.

h1 = {:x => {:y => [4,5,6]}, :z => [7,8,9]}
h2 = {:x => {:y => [7,8,9]}, :z => "xyz"}

h1.deep_merge(h2) #=> { :x => {:y => [7, 8, 9]}, :z => "xyz" }
h2.deep_merge(h1) #=> { :x => {:y => [4, 5, 6]}, :z => [7, 8, 9] }
# File activesupport/lib/active_support/core_ext/hash/deep_merge.rb, line 9
def deep_merge(other_hash)
  dup.deep_merge!(other_hash)
end
deep_merge!(other_hash)

Same as deep_merge, but modifies self.

# File activesupport/lib/active_support/core_ext/hash/deep_merge.rb, line 14
def deep_merge!(other_hash)
  other_hash.each_pair do |k,v|
    tv = self[k]
    self[k] = tv.is_a?(Hash) && v.is_a?(Hash) ? tv.deep_merge(v) : v
  end
  self
end
diff(h2)

Returns a hash that represents the difference between two hashes.

Examples:

{1 => 2}.diff(1 => 2)         # => {}
{1 => 2}.diff(1 => 3)         # => {1 => 2}
{}.diff(1 => 2)               # => {1 => 2}
{1 => 2, 3 => 4}.diff(1 => 2) # => {3 => 4}
# File activesupport/lib/active_support/core_ext/hash/diff.rb, line 10
def diff(h2)
  dup.delete_if { |k, v| h2[k] == v }.merge!(h2.dup.delete_if { |k, v| has_key?(k) })
end
except(*keys)

Return a hash that includes everything but the given keys. This is useful for limiting a set of parameters to everything but a few known toggles:

@person.update_attributes(params[:person].except(:admin))

If the receiver responds to convert_key, the method is called on each of the arguments. This allows exceptto play nice with hashes with indifferent access for instance:

{:a => 1}.with_indifferent_access.except(:a)  # => {}
{:a => 1}.with_indifferent_access.except("a") # => {}
# File activesupport/lib/active_support/core_ext/hash/except.rb, line 14
def except(*keys)
  dup.except!(*keys)
end
except!(*keys)

Replaces the hash without the given keys.

# File activesupport/lib/active_support/core_ext/hash/except.rb, line 19
def except!(*keys)
  keys.each { |key| delete(key) }
  self
end
extract!(*keys)

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}
# File activesupport/lib/active_support/core_ext/hash/slice.rb, line 35
def extract!(*keys)
  result = {}
  keys.each {|key| result[key] = delete(key) }
  result
end
extractable_options?()

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
from_trusted_xml(xml)
# File activesupport/lib/active_support/core_ext/hash/conversions.rb, line 101
def from_trusted_xml(xml)
  from_xml xml, []
end
from_xml(xml, disallowed_types = nil)
# File activesupport/lib/active_support/core_ext/hash/conversions.rb, line 97
def from_xml(xml, disallowed_types = nil)
  typecast_xml_value(unrename_keys(ActiveSupport::XmlMini.parse(xml)), disallowed_types)
end
nested_under_indifferent_access()

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 selfif converting to an ActiveSupport::HashWithIndifferentAccesswould not be desirable.

b = {:b => 1}
{:a => b}.with_indifferent_access["a"] # calls b.nested_under_indifferent_access
reverse_merge(other_hash)

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
reverse_merge!(other_hash)

Destructive reverse_merge.

Also aliased as: reverse_update
# 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
reverse_update(other_hash)
Alias for: reverse_merge!
slice(*keys)

Slice a hash to include only the given keys. This is useful for limiting an options hash to valid keys before passing to a method:

def search(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 15
def slice(*keys)
  keys = keys.map! { |key| convert_key(key) } if respond_to?(:convert_key, true)
  hash = self.class.new
  keys.each { |k| hash[k] = self[k] if has_key?(k) }
  hash
end
slice!(*keys)

Replaces the hash with only the given keys. Returns a hash contained 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 25
def slice!(*keys)
  keys = keys.map! { |key| convert_key(key) } if respond_to?(:convert_key, true)
  omit = slice(*self.keys - keys)
  hash = slice(*keys)
  replace(hash)
  omit
end
stringify_keys()

Return a new hash with all keys converted to strings.

{ :name => 'Rob', :years => '28' }.stringify_keys
#=> { "name" => "Rob", "years" => "28" }
# File activesupport/lib/active_support/core_ext/hash/keys.rb, line 6
def stringify_keys
  dup.stringify_keys!
end
stringify_keys!()

Destructively convert all keys to strings. Same as stringify_keys, but modifies self.

# File activesupport/lib/active_support/core_ext/hash/keys.rb, line 12
def stringify_keys!
  keys.each do |key|
    self[key.to_s] = delete(key)
  end
  self
end
symbolize_keys()

Return a new hash with all keys converted to symbols, as long as they respond to to_sym.

{ 'name' => 'Rob', 'years' => '28' }.symbolize_keys
#=> { :name => "Rob", :years => "28" }
Also aliased as: to_options
# File activesupport/lib/active_support/core_ext/hash/keys.rb, line 24
def symbolize_keys
  dup.symbolize_keys!
end
symbolize_keys!()

Destructively convert all keys to symbols, as long as they respond to to_sym. Same as symbolize_keys, but modifies self.

Also aliased as: to_options!
# File activesupport/lib/active_support/core_ext/hash/keys.rb, line 30
def symbolize_keys!
  keys.each do |key|
    self[(key.to_sym rescue key) || key] = delete(key)
  end
  self
end
to_options()
Alias for: symbolize_keys
to_options!()
Alias for: symbolize_keys!
to_param(namespace = nil)

Returns a string representation of the receiver suitable for use as a URL query string:

{:name => 'David', :nationality => 'Danish'}.to_param
# => "name=David&nationality=Danish"

An optional namespace can be passed to enclose the param names:

{:name => 'David', :nationality => 'Danish'}.to_param('user')
# => "user[name]=David&user[nationality]=Danish"

The string pairs “key=value” that conform the query string are sorted lexicographically in ascending order.

This method is also aliased as to_query.

Also aliased as: to_query
# File activesupport/lib/active_support/core_ext/object/to_param.rb, line 50
def to_param(namespace = nil)
  collect do |key, value|
    value.to_query(namespace ? "#{namespace}[#{key}]" : key)
  end.sort * '&'
end
to_query(namespace = nil)
Alias for: to_param
to_xml(options = {})

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 valueis a hash there's a recursive call with keyas :root.

  • If valueis an array there's a recursive call with keyas :root, and keysingularized as :children.

  • If valueis a callable object it must expect one or two arguments. Depending on the arity, the callable is invoked with the optionshash as first argument with keyas :root, and keysingularized as second argument. The callable can add nodes by using options[:builder].

    "foo".to_xml(lambda { |options, key| options[:builder].b(key) })
    # => "<b>foo</b>"
    
  • If valueresponds to to_xmlthe method is invoked with keyas :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 keyas tag is created with a string representation of valueas text node. If valueis nilan attribute “nil” set to “true” is added. Unless the option :skip_typesexists and is true, an attribute “type” is added as well according to the following mapping:

    XML_TYPE_NAMES = {
      "Symbol"     => "symbol",
      "Fixnum"     => "integer",
      "Bignum"     => "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 :rootoption.

The default XML builder is a fresh instance of Builder::XmlMarkup. You can configure your own builder with the :builderoption. The method also accepts options like :dasherizeand friends, they are forwarded to the builder.

# File activesupport/lib/active_support/core_ext/hash/conversions.rb, line 69
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.__send__(:method_missing, root) do
    each { |key, value| ActiveSupport::XmlMini.to_tag(key, value, options) }
    yield builder if block_given?
  end
end
with_indifferent_access()

Returns an ActiveSupport::HashWithIndifferentAccessout 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_from_hash_copying_default(self)
end