module Sequel::Plugins::OptimisticLocking

  1. lib/sequel/plugins/optimistic_locking.rb

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
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.


Public Class

  1. apply
  2. configure


Error = Sequel::NoExistingObject  

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

Public Class methods

apply(model, opts=OPTS)

Load the instance_filters plugin into the model.

[show source]
   # File lib/sequel/plugins/optimistic_locking.rb
27 def self.apply(model, opts=OPTS)
28   model.plugin :instance_filters
29 end
configure(model, opts=OPTS)

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

[show source]
   # File lib/sequel/plugins/optimistic_locking.rb
33 def self.configure(model, opts=OPTS)
34   model.lock_column = opts[:lock_column] || :lock_version
35 end