Class: ActiveSupport::CurrentAttributes
- Includes:
- Callbacks
- Defined in:
- 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.
Defined Under Namespace
Modules: TestHelper
Constant Summary collapse
- INVALID_ATTRIBUTE_NAMES =
:nodoc:
[:set, :reset, :resets, :instance, :before_reset, :after_reset, :reset_all, :clear_all]
Constants included from Callbacks
ActiveSupport::Callbacks::CALLBACK_FILTER_TYPES
Instance Attribute Summary collapse
-
#attributes ⇒ Object
Returns the value of attribute attributes.
Class Method Summary collapse
-
.attribute(*names, default: nil) ⇒ Object
Declares one or more attributes that will be given both class and instance accessor methods.
-
.before_reset(*methods, &block) ⇒ Object
Calls this callback before #reset is called on the instance.
-
.clear_all ⇒ Object
:nodoc:.
-
.instance ⇒ Object
Returns singleton instance for this class in this thread.
-
.reset_all ⇒ Object
:nodoc:.
-
.resets(*methods, &block) ⇒ Object
(also: after_reset)
Calls this callback after #reset is called on the instance.
Instance Method Summary collapse
-
#initialize ⇒ CurrentAttributes
constructor
A new instance of CurrentAttributes.
-
#reset ⇒ Object
Reset all attributes.
-
#set(attributes, &block) ⇒ Object
Expose one or more attributes within a block.
Methods included from Callbacks
Methods included from Concern
#append_features, #class_methods, extended, #included, #prepend_features, #prepended
Constructor Details
#initialize ⇒ CurrentAttributes
Returns a new instance of CurrentAttributes.
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# File 'lib/active_support/current_attributes.rb', line 196 def initialize @attributes = resolve_defaults end |
Instance Attribute Details
#attributes ⇒ Object
Returns the value of attribute attributes.
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# File 'lib/active_support/current_attributes.rb', line 194 def attributes @attributes end |
Class Method Details
.attribute(*names, default: nil) ⇒ Object
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.
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# File 'lib/active_support/current_attributes.rb', line 112 def attribute(*names, default: nil) 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) ⇒ Object
Calls this callback before #reset is called on the instance. Used for resetting external collaborators that depend on current values.
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# File 'lib/active_support/current_attributes.rb', line 142 def before_reset(*methods, &block) set_callback :reset, :before, *methods, &block end |
.clear_all ⇒ Object
:nodoc:
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# File 'lib/active_support/current_attributes.rb', line 158 def clear_all # :nodoc: reset_all current_instances.clear end |
.instance ⇒ Object
Returns singleton instance for this class in this thread. If none exists, one is created.
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# File 'lib/active_support/current_attributes.rb', line 100 def instance current_instances[current_instances_key] ||= new end |
.reset_all ⇒ Object
:nodoc:
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# File 'lib/active_support/current_attributes.rb', line 154 def reset_all # :nodoc: current_instances.each_value(&:reset) end |
.resets(*methods, &block) ⇒ Object Also known as: after_reset
Calls this callback after #reset is called on the instance. Used for resetting external collaborators, like Time.zone.
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# File 'lib/active_support/current_attributes.rb', line 147 def resets(*methods, &block) set_callback :reset, :after, *methods, &block end |
Instance Method Details
#reset ⇒ Object
Reset all attributes. Should be called before and after actions, when used as a per-request singleton.
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# File 'lib/active_support/current_attributes.rb', line 215 def reset run_callbacks :reset do self.attributes = resolve_defaults end end |
#set(attributes, &block) ⇒ Object
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
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# File 'lib/active_support/current_attributes.rb', line 210 def set(attributes, &block) with(**attributes, &block) end |