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

DBIx::Class::Helper::ResultSet::CorrelateRelationship(3pUser Contributed Perl DocumentatDBIx::Class::Helper::ResultSet::CorrelateRelationship(3pm)

NAME

       DBIx::Class::Helper::ResultSet::CorrelateRelationship - Easily correlate your ResultSets

VERSION

       version 2.013002

SYNOPSIS

	package MyApp::Schema::ResultSet::Author;

	use base 'DBIx::Class::ResultSet';

	__PACKAGE__->load_components(qw(Helper::ResultSet::CorrelateRelationship));

	sub with_book_count {
	  my $self = shift;

	  $self->search(undef, {
	    '+columns' => {
	      book_count => $self->correlate('book')->count_rs->as_query
	    }
	  });
	}

	1;

       And then elsewhere, like in a controller:

	my $rows = $schema->resultset('Author')->with_book_count->all;

DESCRIPTION

       Correlated queries are one of the coolest things I've learned about for SQL since my initial learning of SQL.  Unfortunately they are
       somewhat confusing.  DBIx::Class has supported doing them for a long time, but generally people don't think of them because they are so
       rare.  I won't go through all the details of how they work and cool things you can do with them, but here are a couple high level things
       you can use them for to save you time or effort.

       If you want to select a list of authors and counts of books for each author, you could use "group_by" and something like "COUNT(book.id)",
       but then you'd need to make your select list match your "group_by" and it would just be a hassle forever after that.  The "SYNOPSIS" is a
       perfect example of how to implement this.

       If you want to select a list of authors and two separate kinds of counts of books for each author, as far as I know, you must use a
       correlated subquery in DBIx::Class.  Here is an example of how you might do that:

	package MyApp::Schema::ResultSet::Author;

	use base 'DBIx::Class::ResultSet';

	__PACKAGE__->load_components(qw(Helper::ResultSet::CorrelateRelationship));

	sub with_good_book_count {
	  my $self = shift;

	  $self->search(undef, {
	    '+columns' => {
	      good_book_count => $self->correlate('books')->good->count_rs->as_query
	    }
	  });
	}

	sub with_bad_book_count {
	  my $self = shift;

	  $self->search(undef, {
	    '+columns' => {
	      bad_book_count => $self->correlate('books')->bad->count_rs->as_query
	    }
	  });
	}

	1;

       And then elsewhere, like in a controller:

	my $rows = $schema->resultset('Author')
	  ->with_bad_book_count
	  ->with_good_book_count
	  ->all;

       This assumes that the Book resultset has "good" and "bad" methods.

       See "NOTE" in DBIx::Class::Helper::ResultSet for a nice way to apply it to your entire schema.

METHODS

   correlate
	$rs->correlate($relationship_name)

       Correlate takes a single argument, a relationship for the invocant, and returns a resultset that can be used in the selector list.

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::CorrelateRelationship(3pm)

Check Out this Related Man Page

DBIx::Class::Helper::Schema::GenerateSource(3pm)	User Contributed Perl Documentation	  DBIx::Class::Helper::Schema::GenerateSource(3pm)

NAME

       DBIx::Class::Helper::Schema::GenerateSource - Generate sources directly from your Schema

VERSION

       version 2.013002

SYNOPSIS

	package MyApp::Schema;

	__PACKAGE__->load_components('Helper::Schema::GenerateSource');

	__PACKAGE__->generate_source(User => 'MyCompany::BaseResult::User');

DESCRIPTION

       This helper allows you to handily and correctly add new result sources to your schema based on existing result sources.	Typically this
       would be done with something like:

	package MyApp::Schema::Result::MessegeQueue;

	use parent 'MyCo::Schema::Result::MessageQueue';

	__PACKAGE__->table(__PACKAGE__->table);

	1;

       which clearly is in its own file.  This should still be done when you need to add columns or really do anything other than just basic
       addition of the result source to your schema.

       Note: This component correctly generates an "anonymous" subclass of the given base class.  Do not depend on the name of the subclass as it
       is currently considered unstable.

METHODS

   generate_source
	$schema->generate_source(User => 'MyCompany::BaseResult::User')

       The first argument to "generate_source" is the "moniker" to register the class as, the second argument is the base class for the new result
       source.

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::Schema::GenerateSource(3pm)

Linux and UNIX Man Pages

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

Check Out this Related Man Page