Module: GraphMediator

Defined in:
lib/graph_mediator.rb,
lib/graph_mediator/locking.rb,
lib/graph_mediator/version.rb,
lib/graph_mediator/mediator.rb

Overview

GraphMediator

GraphMediator is used to coordinate changes between a graph of ActiveRecord objects related to a root node. See README.rdoc for details.

GraphMediator::Base::DSL - is the simple class macro language used to set up mediation.

Versioning and Optimistic Locking

If you include an integer lock_version column in your class, it will be incremented only once within a mediated_transaction and will serve as the optimistic locking check for the entire graph so long as you have declared all your dependent models for mediation.

Outside of a mediated_transaction, lock_version will increment per update as usual.

Convenience Methods for Save Without Mediation

There are convenience method to perform a save, save!, toggle, toggle!, update_attribute, update_attributes or update_attributes! call without mediation. They are of the form <method>_without_mediation<punc>

For example, save_without_mediation! is equivalent to:

instance.disable_mediation!
instance.save!
instance.enable_mediation!

Overriding

GraphMediator overrides ActiveRecord’s save_without_transaction to slip in mediation just before the save process is wrapped in a transaction.

  • save_without_transaction

  • save_without_transaction_with_mediation

  • save_without_transaction_without_mediation

may all be overridden in your implementation class, but they end up being defined locally by GraphMediator, so you can override with something like alias_method_chain, but will need to be in a subclass to use super.

My original intention was to define aliased overrides in MediatorProxy if the target was a method in a superclass (like save), so that the implementation class could make a simple def foo; something; super; end override, but this is prevented by a bug in ruby 1.8 with aliasing of methods that use super in a module. redmine.ruby-lang.org/issues/show/734

Defined Under Namespace

Modules: AliasExtension, Configuration, DSL, Locking, Proxy, Util Classes: Mediator, MediatorException

Constant Summary collapse

CALLBACKS = 
[:before_mediation, :mediate_reconciles, :mediate_caches, :mediate_bumps]
SAVE_METHODS = 
[:save_without_transactions, :save_without_transactions!]
VERSION = 
"0.2.3"

Class Method Summary collapse

Class Method Details

.included(base) ⇒ Object 



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# File 'lib/graph_mediator.rb', line 67

def included(base)
  base.class_eval do
    extend DSL
  end
  initialize_for_mediation(base)
end