allow the 'lock_version' column to be configured with set_locking_column. Closes #3402

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3422 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/CHANGELOG

 *SVN*
 
+* Allow configuration of the column used for optimistic locking [wilsonb@gmail.com]
+
 * Don't hardcode 'id' in acts as list.  [ror@philippeapril.com]
 
 * Fix date errors for SQLServer in association tests. #3406 [kevin.clark@gmal.com]

activerecord/lib/active_record/locking.rb

@@ -18,6 +18,8 @@ module ActiveRecord
   # You must ensure that your database schema defaults the lock_version column to 0.
   #
   # This behavior can be turned off by setting <tt>ActiveRecord::Base.lock_optimistically = false</tt>.
+  # To override the name of the lock_version column, invoke the <tt>set_locking_column</tt> method.
+  # This method uses the same syntax as <tt>set_table_name</tt>
   module Locking
     def self.append_features(base) #:nodoc:
       super
@@ -29,13 +31,15 @@ def self.append_features(base) #:nodoc:
 
     def update_with_lock #:nodoc:
       if locking_enabled?
-        previous_value    = self.lock_version
-        self.lock_version = previous_value + 1
+        lock_col = self.class.locking_column
+        previous_value = send(lock_col)
+        send(lock_col + '=', previous_value + 1)
         
         affected_rows = connection.update(<<-end_sql, "#{self.class.name} Update with optimistic locking")
           UPDATE #{self.class.table_name}
           SET #{quoted_comma_pair_list(connection, attributes_with_quotes(false))}
-          WHERE #{self.class.primary_key} = #{quote(id)} AND lock_version = #{quote(previous_value)}
+          WHERE #{self.class.primary_key} = #{quote(id)} 
+          AND #{lock_col} = #{quote(previous_value)}
         end_sql
 
         unless affected_rows == 1
@@ -52,7 +56,24 @@ class Base
     cattr_accessor :lock_optimistically
 
     def locking_enabled? #:nodoc:
-      lock_optimistically && respond_to?(:lock_version)
+      lock_optimistically && respond_to?(self.class.locking_column)
     end
+    
+    class << self
+      def set_locking_column( value=nil, &block )
+          define_attr_method :locking_column, value, &block
+      end
+  
+      def locking_column
+        reset_locking_column
+      end
+  
+      def reset_locking_column
+        default = 'lock_version'
+        set_locking_column(default)
+        default
+      end
+    end
+    
   end
 end

activerecord/test/fixtures/db_definitions/db2.drop.sql

@@ -25,3 +25,4 @@ DROP TABLE categories_posts;
 DROP TABLE fk_test_has_pk;
 DROP TABLE fk_test_has_fk;
 DROP TABLE keyboards;
+DROP TABLE legacy_things;

activerecord/test/fixtures/db_definitions/db2.sql

@@ -194,3 +194,11 @@ CREATE TABLE fk_test_has_fk (
 
   FOREIGN KEY (fk_id) REFERENCES fk_test_has_pk(id)
 );
+
+--This table has an altered lock_version column name
+CREATE TABLE legacy_things (
+  id INT GENERATED BY DEFAULT AS IDENTITY (START WITH 10000),
+  tps_report_number INT DEFAULT NULL,
+  version INT DEFAULT 0,
+  PRIMARY KEY (id)
+);

activerecord/test/fixtures/db_definitions/firebird.drop.sql

@@ -26,6 +26,7 @@ DROP TABLE fk_test_has_fk;
 DROP TABLE fk_test_has_pk;
 DROP TABLE keyboards;
 DROP TABLE defaults;
+DROP TABLE legacy_things;
 
 DROP DOMAIN D_BOOLEAN;
 

activerecord/test/fixtures/db_definitions/firebird.sql

@@ -257,3 +257,12 @@ CREATE TABLE defaults (
 );
 CREATE GENERATOR defaults_seq;
 SET GENERATOR defaults_seq TO 10000;
+
+CREATE TABLE legacy_things (
+  id BIGINT NOT NULL,
+  tps_report_number INTEGER,
+  version INTEGER DEFAULT 0 NOT NULL,
+  PRIMARY KEY (id)
+);
+CREATE GENERATOR legacy_things_seq;
+SET GENERATOR legacy_things_seq TO 10000;

activerecord/test/fixtures/db_definitions/mysql.drop.sql

@@ -25,3 +25,4 @@ DROP TABLE categories_posts;
 DROP TABLE fk_test_has_fk;
 DROP TABLE fk_test_has_pk;
 DROP TABLE keyboards;
+DROP TABLE legacy_things;

activerecord/test/fixtures/db_definitions/mysql.sql

@@ -197,3 +197,11 @@ CREATE TABLE `keyboards` (
   `key_number` int(11) NOT NULL auto_increment primary key,
   `name` varchar(50) default NULL
 );
+
+--Altered lock_version column name.
+CREATE TABLE `legacy_things` (
+  `id` int(11) NOT NULL auto_increment,
+  `tps_report_number` int(11) default NULL,
+  `version` int(11) NOT NULL default 0,
+  PRIMARY KEY  (`id`)
+) TYPE=InnoDB;

activerecord/test/fixtures/db_definitions/oci.drop.sql

@@ -26,6 +26,8 @@ drop table posts;
 drop table fk_test_has_pk;
 drop table fk_test_has_fk;
 drop table keyboards;
+drop table legacy_things;
+
 drop sequence accounts_seq;
 drop sequence companies_nonstd_seq;
 drop sequence topics_seq;
@@ -53,3 +55,4 @@ drop sequence categories_posts_seq;
 drop sequence fk_test_has_pk_seq;
 drop sequence fk_test_has_fk_seq;
 drop sequence keyboards_seq;
+drop sequence legacy_things_seq;

activerecord/test/fixtures/db_definitions/oci.sql

@@ -269,3 +269,10 @@ create table test_oci_defaults (
 );
 create sequence test_oci_defaults_seq minvalue 10000;
 
+--This table has an altered lock_version column name.
+create table legacy_things (
+    id integer not null primary key,
+    tps_report_number integer default null,
+    version integer default 0
+);
+create sequence legacy_things_seq minvalue 10000;

activerecord/test/fixtures/db_definitions/postgresql.drop.sql

@@ -28,3 +28,4 @@ DROP TABLE fk_test_has_fk;
 DROP TABLE fk_test_has_pk;
 DROP TABLE geometrics;
 DROP TABLE keyboards;
+DROP TABLE legacy_things;

activerecord/test/fixtures/db_definitions/postgresql.sql

@@ -225,3 +225,10 @@ CREATE TABLE keyboards (
   key_number serial primary key,
   "name" character varying(50)
 );
+
+--Altered lock_version column name.
+CREATE TABLE legacy_things (
+  id serial primary key,
+  tps_report_number integer,
+  version integer default 0
+);

activerecord/test/fixtures/db_definitions/sqlite.drop.sql

@@ -25,3 +25,4 @@ DROP TABLE categories_posts;
 DROP TABLE fk_test_has_fk;
 DROP TABLE fk_test_has_pk;
 DROP TABLE keyboards;
+DROP TABLE legacy_things;

activerecord/test/fixtures/db_definitions/sqlite.sql

@@ -181,3 +181,10 @@ CREATE TABLE 'keyboards' (
   'key_number' INTEGER PRIMARY KEY NOT NULL,
   'name' VARCHAR(255) DEFAULT NULL
 );
+
+--Altered lock_version column name.
+CREATE TABLE 'legacy_things' (
+  'id' INTEGER NOT NULL PRIMARY KEY,
+  'tps_report_number' INTEGER DEFAULT NULL,
+  'version' INTEGER NOT NULL DEFAULT 0
+)

activerecord/test/fixtures/db_definitions/sqlserver.drop.sql

@@ -25,3 +25,4 @@ DROP TABLE categories_posts;
 DROP TABLE fk_test_has_fk;
 DROP TABLE fk_test_has_pk;
 DROP TABLE keyboards;
+DROP TABLE legacy_things;

activerecord/test/fixtures/db_definitions/sqlserver.sql

@@ -181,3 +181,11 @@ CREATE TABLE keyboards (
   key_number int NOT NULL IDENTITY(1, 1) PRIMARY KEY,
   name varchar(50) default NULL
 );
+
+--This table has an altered lock_version column name.
+CREATE TABLE legacy_things (
+  id int NOT NULL IDENTITY(1, 1),
+  tps_report_number int default NULL,
+  version int default 0,
+  PRIMARY KEY (id)
+);

activerecord/test/fixtures/legacy_thing.rb

+class LegacyThing < ActiveRecord::Base
+  set_locking_column :version
+end

activerecord/test/fixtures/legacy_things.yml

+obtuse:
+  id: 1
+  tps_report_number: 500

activerecord/test/locking_test.rb

 require 'abstract_unit'
 require 'fixtures/person'
+require 'fixtures/legacy_thing'
 
 class LockingTest < Test::Unit::TestCase
-  fixtures :people
+  fixtures :people, :legacy_things
 
   def test_lock_existing
     p1 = Person.find(1)
@@ -28,5 +29,18 @@ def test_lock_new
       p2.first_name = "should fail"
       p2.save
     }
+  end
+  
+  def test_lock_column_name_existing
+    t1 = LegacyThing.find(1)
+    t2 = LegacyThing.find(1)
+    t1.tps_report_number = 400
+    t1.save
+
+    assert_raises(ActiveRecord::StaleObjectError) {
+      t2.tps_report_number = 300
+      t2.save
+    }
   end 
+
 end