DOKK / manpages / debian 10 / libjifty-dbi-perl / Jifty::DBI::Collection::Unique.3pm.en
Jifty::DBI::Collection::Unique(3pm) User Contributed Perl Documentation Jifty::DBI::Collection::Unique(3pm)

Overrides add_record to ensure uniqueness.

Jifty::DBI::Collection::Unique - Ensure uniqueness of records in a collection

    package Foo::Collection;
    use base 'Jifty::DBI::Collection';
    use Jifty::DBI::Collection::Unique; # mixin
    my $collection = Foo::Collection->New();
    $collection->SetupComplicatedJoins;
    $collection->OrderByMagic;
    
    while (my $thing = $collection->Next) {
        # $thing is going to be distinct
    }

Currently, Jifty::DBI makes exceptions for databases which cannot handle both "SELECT DISTINCT" and ordering in the same statement; it drops the "DISTINCT" requirement. This, of course, means that you can get the same row twice, which you might not want. If that's the case, use this module as a mix-in, and it will provide you with an "AddRecord" method which ensures that a record will not appear twice in the same search.

Simon Cozens.

Copyright 2005 Best Practical Solutions, LLC

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

2014-05-29 perl v5.20.2