/ 
DBIx-ScopedTransaction-1.0.2
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/ DBIx::ScopedTransaction

NAME

DBIx::ScopedTransaction - Scope database transactions on DBI handles in code, to detect and prevent issues with unterminated transactions.

VERSION

Version 1.0.2

SYNOPSIS

use DBIx::ScopedTransaction;
use Try::Tiny;

# Optional, define custom logger for errors detected when destroying a
# transaction object. By default, this prints to STDERR.
local $DBIx::ScopedTransaction::DESTROY_LOGGER = sub
{
	my ( $messages ) = @_;
	
	foreach $message ( @$messages )
	{
		warn "DBIx::ScopedTransaction: $message";
	}
};

# Start a transaction on $dbh - this in turn calls $dbh->begin_work();
my $transaction = DBIx::ScopedTransaction->new( $dbh );
try
{
	# Do some work on $dbh that may succeed or fail.
}
finally
{
	my @errors = @_;
	if ( scalar( @errors ) == 0 )
	{
		$transaction->commit() || die 'Failed to commit transaction';
	}
	else
	{
		$transaction->rollback() || die 'Failed to roll back transaction.';
	}
};

DESCRIPTION

Small class designed to be instantiated in a localized scope. Its purpose is to start and then clean up a transaction on a DBI object, while detecting cases where the transaction isn't terminated properly.

The synopsis has an example of working code, let's see here an example in which DBIx::ScopedTransaction helps us to detect a logic error in how the programmer handled terminating the transaction.

sub test
{
	my $transaction = DBIx::ScopedTransaction->new( $dbh );
	try
	{
		# Do some work on $dbh that may succeed or fail.
	}
	catch
	{
		$transaction->rollback();
	}
}

test();

As soon as the test() function has been run, $transaction goes out of scope and gets destroyed by Perl. DBIx::ScopedTransaction subclasses destroy and detects that the underlying transaction has neither been committed nor rolled back, and forces a rollback for safety as well as prints details on what code should be reviewed on STDERR.

FUNCTIONS

new()

Creates a new transaction.

my $transaction = DBIx::ScopedTransaction->new(
	$database_handle,
);

get_database_handle()

Returns the database handle the current transaction is operating on.

my $database_handle = get_database_handle();

is_active()

Returns whether the current transaction object is active.

my $boolean = $self->is_active();
my $boolean = $self->is_active( $boolean );

commit()

Commits the current transaction.

my $boolean = $self->commit();

rollback()

Rolls back the current transaction.

my $boolean = $self->rollback();

_default_destroy_logger()

Log to STDERR warnings and errors that occur when a DBIx::ScopedTransaction object is destroyed.

_default_destroy_logger( $messages );

To override this default logger you can localize $DBIx::ScopedTransaction::DESTROY_LOGGER. For example:

local $DBIx::ScopedTransaction::DESTROY_LOGGER = sub
{
	my ( $messages ) = @_;
	
	foreach $message ( @$messages )
	{
		warn "DBIx::ScopedTransaction: $message";
	}
};

DESTROY()

Clean up function to detect unterminated transactions and try to roll them back safely before destroying the DBIx::ScopedTransaction object.

AUTHOR

Guillaume Aubert, <aubertg at cpan.org>.

BUGS

Please report any bugs or feature requests to bug-dbix-scopedtransaction at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=DBIx::ScopedTransaction. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SUPPORT

You can find documentation for this module with the perldoc command.

perldoc DBIx::ScopedTransaction

You can also look for information at:

ACKNOWLEDGEMENTS

Thanks to ThinkGeek (http://www.thinkgeek.com/) and its corporate overlords at Geeknet (http://www.geek.net/), for footing the bill while I write code for them!

COPYRIGHT & LICENSE

Copyright 2012 Guillaume Aubert.

This program is free software; you can redistribute it and/or modify it under the terms of the Artistic License.

See http://dev.perl.org/licenses/ for more information.