class OpenStruct

Parent:
Object

An OpenStruct is a data structure, similar to a Hash, that allows the definition of arbitrary attributes with their accompanying values. This is accomplished by using Ruby's metaprogramming to define methods on the class itself.

Examples

require "ostruct"

person = OpenStruct.new
person.name = "John Smith"
person.age  = 70

person.name      # => "John Smith"
person.age       # => 70
person.address   # => nil

An OpenStruct employs a Hash internally to store the attributes and values and can even be initialized with one:

australia = OpenStruct.new(:country => "Australia", :capital => "Canberra")
  # => #<OpenStruct country="Australia", capital="Canberra">

Hash keys with spaces or characters that could normally not be used for method calls (e.g. ()[]*) will not be immediately available on the OpenStruct object as a method for retrieval or assignment, but can still be reached through the Object#send method.

measurements = OpenStruct.new("length (in inches)" => 24)
measurements.send("length (in inches)")   # => 24

message = OpenStruct.new(:queued? => true)
message.queued?                           # => true
message.send("queued?=", false)
message.queued?                           # => false

Removing the presence of an attribute requires the execution of the #delete_field method as setting the property value to nil will not remove the attribute.

first_pet  = OpenStruct.new(:name => "Rowdy", :owner => "John Smith")
second_pet = OpenStruct.new(:name => "Rowdy")

first_pet.owner = nil
first_pet                 # => #<OpenStruct name="Rowdy", owner=nil>
first_pet == second_pet   # => false

first_pet.delete_field(:owner)
first_pet                 # => #<OpenStruct name="Rowdy">
first_pet == second_pet   # => true

Implementation

An OpenStruct utilizes Ruby's method lookup structure to find and define the necessary methods for properties. This is accomplished through the methods method_missing and define_singleton_method.

This should be a consideration if there is a concern about the performance of the objects that are created, as there is much more overhead in the setting of these properties compared to using a Hash or a Struct.

Public Class Methods

json_create(object) Show source
# File ext/json/lib/json/add/ostruct.rb, line 11
def self.json_create(object)
  new(object['t'] || object[:t])
end

Deserializes JSON string by constructing new Struct object with values t serialized by to_json.

new(hash=nil) Show source
# File lib/ostruct.rb, line 90
def initialize(hash=nil)
  @table = {}
  if hash
    hash.each_pair do |k, v|
      k = k.to_sym
      @table[k] = v
    end
  end
end

Creates a new OpenStruct object. By default, the resulting OpenStruct object will have no attributes.

The optional hash, if given, will generate attributes and values (can be a Hash, an OpenStruct or a Struct). For example:

require "ostruct"
hash = { "country" => "Australia", :capital => "Canberra" }
data = OpenStruct.new(hash)

data   # => #<OpenStruct country="Australia", capital="Canberra">

Public Instance Methods

==(other) Show source
# File lib/ostruct.rb, line 346
def ==(other)
  return false unless other.kind_of?(OpenStruct)
  @table == other.table!
end

Compares this object and other for equality. An OpenStruct is equal to other when other is an OpenStruct and the two objects' Hash tables are equal.

require "ostruct"
first_pet  = OpenStruct.new("name" => "Rowdy")
second_pet = OpenStruct.new(:name  => "Rowdy")
third_pet  = OpenStruct.new("name" => "Rowdy", :age => nil)

first_pet == second_pet   # => true
first_pet == third_pet    # => false
ostruct[name] → object Show source
# File lib/ostruct.rb, line 226
def [](name)
  @table[name.to_sym]
end

Returns the value of an attribute.

require "ostruct"
person = OpenStruct.new("name" => "John Smith", "age" => 70)
person[:age]   # => 70, same as person.age
ostruct[name] = obj → obj Show source
# File lib/ostruct.rb, line 241
def []=(name, value)
  modifiable?[new_ostruct_member!(name)] = value
end

Sets the value of an attribute.

require "ostruct"
person = OpenStruct.new("name" => "John Smith", "age" => 70)
person[:age] = 42   # equivalent to person.age = 42
person.age          # => 42
as_json(*) Show source
# File ext/json/lib/json/add/ostruct.rb, line 17
def as_json(*)
  klass = self.class.name
  klass.to_s.empty? and raise JSON::JSONError, "Only named structs are supported!"
  {
    JSON.create_id => klass,
    't'            => table,
  }
end

Returns a hash, that will be turned into a JSON object and represent this object.

delete_field(name) Show source
# File lib/ostruct.rb, line 290
def delete_field(name)
  sym = name.to_sym
  begin
    singleton_class.__send__(:remove_method, sym, "#{sym}=")
  rescue NameError
  end
  @table.delete(sym) do
    raise NameError.new("no field `#{sym}' in #{self}", sym)
  end
end

Removes the named field from the object. Returns the value that the field contained if it was defined.

require "ostruct"

person = OpenStruct.new(name: "John", age: 70, pension: 300)

person.delete_field("age")   # => 70
person                       # => #<OpenStruct name="John", pension=300>

Setting the value to nil will not remove the attribute:

person.pension = nil
person                 # => #<OpenStruct name="John", pension=nil>
dig(name, ...) → object Show source
# File lib/ostruct.rb, line 265
def dig(name, *names)
  begin
    name = name.to_sym
  rescue NoMethodError
    raise TypeError, "#{name} is not a symbol nor a string"
  end
  @table.dig(name, *names)
end

Extracts the nested value specified by the sequence of name objects by calling dig at each step, returning nil if any intermediate step is nil.

require "ostruct"
address = OpenStruct.new("city" => "Anytown NC", "zip" => 12345)
person  = OpenStruct.new("name" => "John Smith", "address" => address)

person.dig(:address, "zip")            # => 12345
person.dig(:business_address, "zip")   # => nil

data = OpenStruct.new(:array => [1, [2, 3]])

data.dig(:array, 1, 0)   # => 2
data.dig(:array, 0, 0)   # TypeError: Integer does not have #dig method
each_pair {|name, value| block } → ostruct Show source
each_pair → Enumerator
# File lib/ostruct.rb, line 130
def each_pair
  return to_enum(__method__) { @table.size } unless block_given?
  @table.each_pair{|p| yield p}
  self
end

Yields all attributes (as symbols) along with the corresponding values or returns an enumerator if no block is given.

require "ostruct"
data = OpenStruct.new("country" => "Australia", :capital => "Canberra")
data.each_pair.to_a   # => [[:country, "Australia"], [:capital, "Canberra"]]
eql?(other) Show source
# File lib/ostruct.rb, line 356
def eql?(other)
  return false unless other.kind_of?(OpenStruct)
  @table.eql?(other.table!)
end

Compares this object and other for equality. An OpenStruct is eql? to other when other is an OpenStruct and the two objects' Hash tables are eql?.

freeze() Show source
# File lib/ostruct.rb, line 187
def freeze
  @table.each_key {|key| new_ostruct_member!(key)}
  super
end
Calls superclass method Object#freeze
hash() Show source
# File lib/ostruct.rb, line 366
def hash
  @table.hash
end

Computes a hash code for this OpenStruct. Two OpenStruct objects with the same content will have the same hash code (and will compare using eql?).

See also Object#hash.

inspect() Show source
# File lib/ostruct.rb, line 306
def inspect
  str = "#<#{self.class}"

  ids = (Thread.current[InspectKey] ||= [])
  if ids.include?(object_id)
    return str << ' ...>'
  end

  ids << object_id
  begin
    first = true
    for k,v in @table
      str << "," unless first
      first = false
      str << " #{k}=#{v.inspect}"
    end
    return str << '>'
  ensure
    ids.pop
  end
end

Returns a string containing a detailed summary of the keys and values.

Also aliased as: to_s
marshal_dump() Show source
# File lib/ostruct.rb, line 139
def marshal_dump
  @table
end

Provides marshalling support for use by the Marshal library.

marshal_load(x) Show source
# File lib/ostruct.rb, line 146
def marshal_load(x)
  @table = x
end

Provides marshalling support for use by the Marshal library.

to_h() Show source
# File lib/ostruct.rb, line 114
def to_h
  @table.dup
end

Converts the OpenStruct to a hash with keys representing each attribute (as symbols) and their corresponding values.

require "ostruct"
data = OpenStruct.new("country" => "Australia", :capital => "Canberra")
data.to_h   # => {:country => "Australia", :capital => "Canberra" }
to_json(*args) Show source
# File ext/json/lib/json/add/ostruct.rb, line 28
def to_json(*args)
  as_json.to_json(*args)
end

Stores class name (OpenStruct) with this struct's values v as a JSON string.

to_s()
Alias for: inspect

Ruby Core © 1993–2017 Yukihiro Matsumoto
Licensed under the Ruby License.
Ruby Standard Library © contributors
Licensed under their own licenses.