Module: Sequel::Plugins::OptimisticLocking

Defined in:
lib/sequel/plugins/optimistic_locking.rb

Overview

This plugin implements a simple database-independent locking mechanism to ensure that concurrent updates do not override changes. This is best implemented by a code example:

class Person < Sequel::Model
  plugin :optimistic_locking
end
p1 = Person[1]
p2 = Person[1]
p1.update(:name=>'Jim') # works
p2.update(:name=>'Bob') # raises Sequel::Plugins::OptimisticLocking::Error

In order for this plugin to work, you need to make sure that the database table has a lock_version column (or other column you name via the lock_column class level accessor) that defaults to 0.

This plugin relies on the instance_filters plugin.

Defined Under Namespace

Modules: ClassMethods, InstanceMethods

Constant Summary collapse

Error =

Exception class raised when trying to update or destroy a stale object.

InstanceFilters::Error

Class Method Summary collapse

Class Method Details

.apply(model, opts = {}) ⇒ Object

Load the instance_filters plugin into the model.



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# File 'lib/sequel/plugins/optimistic_locking.rb', line 27

def self.apply(model, opts={})
  model.plugin :instance_filters
end

.configure(model, opts = {}) ⇒ Object

Set the lock_column to the :lock_column option, or :lock_version if that option is not given.



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# File 'lib/sequel/plugins/optimistic_locking.rb', line 33

def self.configure(model, opts={})
  model.lock_column = opts[:lock_column] || :lock_version
end