dbix::class::helper::resultset::virtualview(3pm) [debian man page]

DBIx::Class::Helper::ResultSet::VirtualView(3pm)	User Contributed Perl Documentation	  DBIx::Class::Helper::ResultSet::VirtualView(3pm)

NAME

       DBIx::Class::Helper::ResultSet::VirtualView - Clean up your SQL namespace (DEPRECATED)

VERSION

       version 2.013002

SYNOPSIS

	# note that this is normally a component for a ResultSet
	package MySchema::ResultSet::Bar;

	use strict;
	use warnings;

	use parent 'DBIx::Class::ResultSet';

	__PACKAGE__->load_components('Helper::ResultSet::VirtualView');

	# and then in code that uses the ResultSet Join with relation x
	my $rs = $schema->resultset('Bar')->search({'x.name' => 'abc'},{ join => 'x' });

	# 'x' now pollutes the query namespace

	# So the following works as expected
	my $ok_rs = $rs->search({'x.other' => 1});

	# But this doesn't: instead of finding a 'Bar' related to two x rows (abc and
	# def) we look for one row with contradictory terms and join in another table
	# (aliased 'x_2') which we never use
	my $broken_rs = $rs->search({'x.name' => 'def'});

	my $rs2 = $rs->as_virtual_view;

	# doesn't work - 'x' is no longer accessible in $rs2, having been sealed away
	my $not_joined_rs = $rs2->search({'x.other' => 1});

	# works as expected: finds a 'table' row related to two x rows (abc and def)
	my $correctly_joined_rs = $rs2->search({'x.name' => 'def'});

DESCRIPTION

       This component is will allow you to clean up your SQL namespace.  See "NOTE" in DBIx::Class::Helper::ResultSet for a nice way to apply it
       to your entire schema.

DEPRECATED

       This component has been suplanted by DBIx::Class::ResultSet::as_subselect_rs.  In the next major version(3) we will begin issuing a
       warning on it's use.  In the major version after that(4) we will remove it entirely.

METHODS

   as_virtual_view
       Act as a barrier to SQL symbols.  The resultset provided will be made into a "virtual view" by including it as a subquery within the from
       clause.	From this point on, any joined tables are inaccessible to ->search on the resultset (as if it were simply where-filtered without
       joins).	See "SYNOPSIS" for example.

NOTE

       You don't have to use this as a Component.  If you prefer you can use it in the following manner:

	# in code using ResultSet:
	use DBIx::Class:Helper::VirtualView;

	my $new_rs = DBIx::Class::Helper::VirtualView::as_virtual_view($rs);

THANKS

       Thanks to ijw from #dbix-class for the idea for this helper (originally called seal), most of the code, and most of the documentation.

AUTHOR

       Arthur Axel "fREW" Schmidt <frioux+cpan@gmail.com>

COPYRIGHT AND LICENSE

       This software is copyright (c) 2012 by Arthur Axel "fREW" Schmidt.

       This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

perl v5.14.2							    2012-06-18			  DBIx::Class::Helper::ResultSet::VirtualView(3pm)

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DBIx::Class::Helper::ResultSet::Random(3pm)		User Contributed Perl Documentation	       DBIx::Class::Helper::ResultSet::Random(3pm)

NAME

       DBIx::Class::Helper::ResultSet::Random - Get random rows from a ResultSet

VERSION

       version 2.013002

SYNOPSIS

	# note that this is normally a component for a ResultSet
	package MySchema::ResultSet::Bar;

	use strict;
	use warnings;

	use parent 'DBIx::Class::ResultSet';

	__PACKAGE__->load_components('Helper::ResultSet::Random');

	# in code using resultset:
	my $random_row	= $schema->resultset('Bar')->rand->single;

DESCRIPTION

       This component allows convenient selection of random rows.  See "NOTE" in DBIx::Class::Helper::ResultSet for a nice way to apply it to your
       entire schema.

       Currently this works by doing something akin to

	SELECT TOP($x) from $table ORDER BY RANDOM()

       Lots of people think this is slow.  My own benchmarks show that doing the above, for 10 rows in a table with just over 8 million rows, is
       nearly instant.	Although that was with SQL Server, and different databases will handle that differently.

       So please, if you have performance issues and want this to work with your database, get in touch and I will do what I can to get it to work
       quickly enough to suite your needs.

METHODS

   rand
       This method takes a single argument, being the size of the random ResultSet to return.  It defaults to 1.  This Component will throw
       exceptions if the argument is not an integer or not greater than zero.

   _rand_order_by
       This module currently does an "ORDER BY" on some db specific function.  If for some reason it guesses incorrectly for your database the
       easiest way to fix that in the short-term (ie without patching upstream) is to override this method.  So for example, if your db uses
       "RAND()" instead of "RANDOM()" and it's not in the predefined list of dbs you could just do the following in your ResultSet class:

	sub _rand_order_by { 'RAND()' }

AUTHOR

       Arthur Axel "fREW" Schmidt <frioux+cpan@gmail.com>

COPYRIGHT AND LICENSE

       This software is copyright (c) 2012 by Arthur Axel "fREW" Schmidt.

       This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

perl v5.14.2							    2012-06-18			       DBIx::Class::Helper::ResultSet::Random(3pm)

Linux and UNIX Man Pages

dbix::class::helper::resultset::virtualview(3pm) [debian man page]

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