Class: ActiveSupport::CurrentAttributes
Relationships & Source Files | |
Namespace Children | |
Modules:
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Super Chains via Extension / Inclusion / Inheritance | |
Class Chain:
self,
DescendantsTracker
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Instance Chain:
self,
Callbacks
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Inherits: | Object |
Defined in: | activesupport/lib/active_support/current_attributes.rb |
Overview
Current Attributes
Abstract super class that provides a thread-isolated attributes singleton, which resets automatically before and after each request. This allows you to keep all the per-request attributes easily available to the whole system.
The following full app-like example demonstrates how to use a Current class to facilitate easy access to the global, per-request attributes without passing them deeply around everywhere:
# app/models/current.rb
class Current < ActiveSupport::CurrentAttributes
attribute :account, :user
attribute :request_id, :user_agent, :ip_address
resets { Time.zone = nil }
def user=(user)
super
self.account = user.account
Time.zone = user.time_zone
end
end
# app/controllers/concerns/authentication.rb
module Authentication
extend ActiveSupport::Concern
included do
before_action :authenticate
end
private
def authenticate
if authenticated_user = User.find_by(id: .encrypted[:user_id])
Current.user = authenticated_user
else
redirect_to new_session_url
end
end
end
# app/controllers/concerns/set_current_request_details.rb
module SetCurrentRequestDetails
extend ActiveSupport::Concern
included do
before_action do
Current.request_id = request.uuid
Current.user_agent = request.user_agent
Current.ip_address = request.ip
end
end
end
class ApplicationController < ActionController::Base
include Authentication
include SetCurrentRequestDetails
end
class MessagesController < ApplicationController
def create
Current.account. .create( )
end
end
class Message < ApplicationRecord
belongs_to :creator, default: -> { Current.user }
after_create { || Event.create(record: ) }
end
class Event < ApplicationRecord
before_create do
self.request_id = Current.request_id
self.user_agent = Current.user_agent
self.ip_address = Current.ip_address
end
end
A word of caution: It’s easy to overdo a global singleton like Current and tangle your model as a result. Current should only be used for a few, top-level globals, like account, user, and request details. The attributes stuck in Current should be used by more or less all actions on all requests. If you start sticking controller-specific attributes in there, you’re going to create a mess.
Constant Summary
-
INVALID_ATTRIBUTE_NAMES =
Internal use only
# File 'activesupport/lib/active_support/current_attributes.rb', line 96[:set, :reset, :resets, :instance, :before_reset, :after_reset, :reset_all, :clear_all]
-
NOT_SET =
Internal use only
# File 'activesupport/lib/active_support/current_attributes.rb', line 98Object.new.freeze
Callbacks
- Included
Callbacks
- Attributes & Methods
- .__callbacks rw
- #__callbacks readonly
Class Attribute Summary
Class Method Summary
-
.after_reset(*methods, &block)
Alias for .resets.
-
.attribute(*names, default: NOT_SET)
Declares one or more attributes that will be given both class and instance accessor methods.
-
.before_reset(*methods, &block)
Calls this callback before #reset is called on the instance.
-
.instance
Returns singleton instance for this class in this thread.
- .new ⇒ CurrentAttributes constructor
-
.resets(*methods, &block)
(also: .after_reset)
Calls this callback after #reset is called on the instance.
- .current_instances private
- .current_instances_key private
- .generated_attribute_methods private
- .method_added(name) private
- .method_missing(name) private
- .respond_to_missing?(name, _) ⇒ Boolean private
- .clear_all Internal use only
- .reset_all Internal use only
DescendantsTracker
- self
Instance Attribute Summary
- #attributes rw
- #attributes=(value) rw
- #defaults readonly
- #defaults? ⇒ Boolean readonly
-
#reset
readonly
Reset all attributes.
-
#set(attributes, &block)
readonly
Expose one or more attributes within a block.
Instance Method Summary
- #resolve_defaults private
Callbacks
- Included
#run_callbacks | Runs the callbacks for the given event. |
#halted_callback_hook | A hook invoked every time a before callback is halted. |
Constructor Details
.new ⇒ CurrentAttributes
# File 'activesupport/lib/active_support/current_attributes.rb', line 199
def initialize @attributes = resolve_defaults end
Class Attribute Details
.__callbacks (rw)
[ GitHub ]# File 'activesupport/lib/active_support/callbacks.rb', line 69
class_attribute :__callbacks, instance_writer: false, instance_predicate: false, default: {}
.defaults (rw)
[ GitHub ]# File 'activesupport/lib/active_support/current_attributes.rb', line 195
class_attribute :defaults, instance_writer: false, default: {}.freeze
.defaults? ⇒ Boolean
(rw)
[ GitHub ]
# File 'activesupport/lib/active_support/current_attributes.rb', line 195
class_attribute :defaults, instance_writer: false, default: {}.freeze
Class Method Details
.after_reset(*methods, &block)
Alias for .resets.
# File 'activesupport/lib/active_support/current_attributes.rb', line 152
alias_method :after_reset, :resets
.attribute(*names, default: NOT_SET)
Declares one or more attributes that will be given both class and instance accessor methods.
Options
-
:default
- The default value for the attributes. If the value
is a proc or lambda, it will be called whenever an instance is constructed. Otherwise, the value will be duplicated with #dup
. Default values are re-assigned when the attributes are reset.
# File 'activesupport/lib/active_support/current_attributes.rb', line 114
def attribute(*names, default: NOT_SET) invalid_attribute_names = names.map(&:to_sym) & INVALID_ATTRIBUTE_NAMES if invalid_attribute_names.any? raise ArgumentError, "Restricted attribute names: #{invalid_attribute_names.join(", ")}" end ActiveSupport::CodeGenerator.batch(generated_attribute_methods, __FILE__, __LINE__) do |owner| names.each do |name| owner.define_cached_method(name, namespace: :current_attributes) do |batch| batch << "def #{name}" << "@attributes[:#{name}]" << "end" end owner.define_cached_method("#{name}=", namespace: :current_attributes) do |batch| batch << "def #{name}=(value)" << "@attributes[:#{name}] = value" << "end" end end end Delegation.generate(singleton_class, names, to: :instance, nilable: false, signature: "") Delegation.generate(singleton_class, names.map { |n| "#{n}=" }, to: :instance, nilable: false, signature: "value") self.defaults = defaults.merge(names.index_with { default }) end
.before_reset(*methods, &block)
Calls this callback before #reset is called on the instance. Used for resetting external collaborators that depend on current values.
# File 'activesupport/lib/active_support/current_attributes.rb', line 144
def before_reset(*methods, &block) set_callback :reset, :before, *methods, &block end
.clear_all
# File 'activesupport/lib/active_support/current_attributes.rb', line 160
def clear_all # :nodoc: reset_all current_instances.clear end
.current_instances (private)
[ GitHub ]# File 'activesupport/lib/active_support/current_attributes.rb', line 170
def current_instances IsolatedExecutionState[:current_attributes_instances] ||= {} end
.current_instances_key (private)
[ GitHub ]# File 'activesupport/lib/active_support/current_attributes.rb', line 174
def current_instances_key @current_instances_key ||= name.to_sym end
.generated_attribute_methods (private)
[ GitHub ].instance
Returns singleton instance for this class in this thread. If none exists, one is created.
# File 'activesupport/lib/active_support/current_attributes.rb', line 102
def instance current_instances[current_instances_key] ||= new end
.method_added(name) (private)
[ GitHub ]# File 'activesupport/lib/active_support/current_attributes.rb', line 186
def method_added(name) super return if name == :initialize return unless public_method_defined?(name) return if respond_to?(name, true) Delegation.generate(singleton_class, [name], to: :instance, as: self, nilable: false) end
.method_missing(name) (private)
[ GitHub ]# File 'activesupport/lib/active_support/current_attributes.rb', line 178
def method_missing(name, ...) instance.public_send(name, ...) end
.reset_all
# File 'activesupport/lib/active_support/current_attributes.rb', line 156
def reset_all # :nodoc: current_instances.each_value(&:reset) end
.resets(*methods, &block) Also known as: .after_reset
# File 'activesupport/lib/active_support/current_attributes.rb', line 149
def resets(*methods, &block) set_callback :reset, :after, *methods, &block end
.respond_to_missing?(name, _) ⇒ Boolean
(private)
# File 'activesupport/lib/active_support/current_attributes.rb', line 182
def respond_to_missing?(name, _) instance.respond_to?(name) || super end
Instance Attribute Details
#__callbacks (readonly)
[ GitHub ]# File 'activesupport/lib/active_support/callbacks.rb', line 69
class_attribute :__callbacks, instance_writer: false, instance_predicate: false, default: {}
#attributes (rw)
[ GitHub ]# File 'activesupport/lib/active_support/current_attributes.rb', line 203
def attributes @attributes.dup end
#attributes=(value) (rw)
[ GitHub ]# File 'activesupport/lib/active_support/current_attributes.rb', line 197
attr_writer :attributes
#defaults (readonly)
[ GitHub ]# File 'activesupport/lib/active_support/current_attributes.rb', line 195
class_attribute :defaults, instance_writer: false, default: {}.freeze
#defaults? ⇒ Boolean
(readonly)
[ GitHub ]
# File 'activesupport/lib/active_support/current_attributes.rb', line 195
class_attribute :defaults, instance_writer: false, default: {}.freeze
#reset (readonly)
Reset all attributes. Should be called before and after actions, when used as a per-request singleton.
#set(attributes, &block) (readonly)
Expose one or more attributes within a block. Old values are returned after the block concludes. Example demonstrating the common use of needing to set Current attributes outside the request-cycle:
class Chat::PublicationJob < ApplicationJob
def perform(attributes, room_number, creator)
Current.set(person: creator) do
Chat::Publisher.publish(attributes: attributes, room_number: room_number)
end
end
end