Added database connection as a yield parameter to ActiveRecord::Base.transaction so you can manually rollback [DHH]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@6196 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

2 files changed, 17 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
index 7d7c22c74b..1b75ab53fe 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
@@ -56,7 +56,7 @@ module ActiveRecord
               begin_db_transaction 
               transaction_open = true
             end
-            yield
+            yield self
           end
         rescue Exception => database_transaction_rollback
           if transaction_open
@@ -79,6 +79,11 @@ module ActiveRecord
       # done if the transaction block raises an exception or returns false.
       def rollback_db_transaction() end
 
+      # Alias for rollback_db_transaction to be used when yielding the transaction
+      def rollback!
+        rollback_db_transaction
+      end
+
       # Alias for #add_limit_offset!.
       def add_limit!(sql, options)
         add_limit_offset!(sql, options) if options
diff --git a/activerecord/lib/active_record/transactions.rb b/activerecord/lib/active_record/transactions.rb
index 77a8a14a2a..d9bfd331c6 100644
--- a/activerecord/lib/active_record/transactions.rb
+++ b/activerecord/lib/active_record/transactions.rb
@@ -32,6 +32,17 @@ module ActiveRecord
     # Exceptions will force a ROLLBACK that returns the database to the state before the transaction was begun. Be aware, though,
     # that the objects by default will _not_ have their instance data returned to their pre-transactional state.
     #
+    # == Rolling back a transaction manually
+    #
+    # Instead of relying on exceptions to rollback your transactions, you can also do so manually from within the scope
+    # of the transaction by accepting a yield parameter and calling rollback! on it. Example:
+    #
+    #   transaction do |transaction|
+    #     david.withdrawal(100)
+    #     mary.deposit(100)
+    #     transaction.rollback! # rolls back the transaction that was otherwise going to be successful
+    #   end
+    #
     # == Transactions are not distributed across database connections
     #
     # A transaction acts on a single database connection.  If you have