Rails - Dec 2004 - Progress on Optimistic Locking

Hey guys,

I''ve made good progress on the optimistic locking mixin I mentioned
earlier.  The examples below  are all ''working''.   I say
''working''
because while the updates fail,  there''s currently no kind of error
condition returned by the adapters when the updates fail.  What''s
required is a return value from connection.update,  ideally the number
of affected rows.  Failling that,  some kind of ''failed'' code
when the
update doesn''t do anything.

Without this kind of information,  I can''t see how I can raise a
StaleObjectError.  So,  I''ve created a ticket (341) requesting this
feature.  I''m unfamiliar with the connections and the adapters, so
I''d
appreciate it if someone else could implement this functionality,  or
something like it.

http://dev.rubyonrails.org/trac.cgi/ticket/341

In the mean time,  I''ll get to work on ''value''
locking,  i.e update
... where id = 1 and attr_one=''old_value'' ......


def some_action
  p1 = Person.find(1)
  p2 =  Person.find(1)

  p1.first_name = "Michael"
  p1.save #UPDATE works

  p2.first_name = "Michael2"
  p2.save # UPDATE ''fails''
end

class Person < ActiveRecord::Base
	include ActiveRecord::Locking
	lock_by :version # default column is ''version_number''
end

class Person < ActiveRecord::Base
	include ActiveRecord::Locking
	lock_by :version, :column=>"some_column"
end

class Person < ActiveRecord::Base
	include ActiveRecord::Locking
	lock_by :date # default column is ''last_modified''
end

class Person < ActiveRecord::Base
	include ActiveRecord::Locking
	lock_by :date => :column=>"some_column
end




-- 
Cheers

Koz