Иван Бахчеев > DBI-Easy-0.24 > DBI::Easy

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NAME ^

DBI::Easy - yet another perl ORM for SQL databases

DESCRIPTION ^

DBI::Easy is another ORM, aimed at making the life of the developer using it a lot easier.

INTRODUCTION ^

The key notions of DBI::Easy are data records, collection of data records and relations between them. A data record is a presentation of SQL result: row or blessed hash, depending on how you look at it. Data records collection is a set of records limited by certain criteria or without any limitations. the differentiation between collections and records has to do with different relations between them: one-to-one, one-to-many, many-to-many.

For Example: Within a domain auction based on DBI::Easy, every user may have a few bids, but each bid belongs to just one concrete user.

It's also worth mentioning the relations between DBI::Easy and SQL. DBI::Easy is currently using a small set of sql, limited to tables and views, including four operations to work with data: insert, update, select, delete. The relations between SQL objects are not formed automatically with the help of constraints.

Also it's important that DBI::Easy is not trying to hide SQL from you. If you need it you can use it fully. However, it allows carrying out the vast majority of simple operations with data without the participation of SQL.

SYNOPSIS ^

Let's start from the most simple things. To start the work you will need two modules that will return database handler ($dbh) upon request.

To avoid unpleasant consequences it's recommended to cache the returned connection only after the fork, if there is a fork in your code. for the case when CL environment variables for DBI_DSN and DBI_* are defined, and they can be used to establish a connection that doesn't need to be cached, you can do without these modules at all. The main task for 'Entity' is to acquire DBI::Easy::Record[::Collection] or one of the child classes.

        package DBEntity;
        use strict;
        use DBI;
        use DBI::Easy::Record;
        use base qw(DBI::Easy::Record);
        sub dbh {               # optional. You don't have to write a procedure similar
                                        # to this one since DBI->connect is requested
                                        # when a ready $dbh hasn't been provided
                return DBI->connect;
        };
        1;

#-----------------------------------------

        package DBEntity::Collection;
        use strict;
        use DBI::Easy::Record::Collection;
        use base qw(DBI::Easy::Record::Collection);
        1;

Now let's get down to something concrete. Let's assume we have a user and his passport data (one-to-one relation) and some contact data (one-to-many) NOTE: the many-to-many relations hasn't been realized yet.

        package Entity::Passport;
        use strict;
        use DBEntity;
        use base qw(DBEntity);
        1;

#-----------------------------------------

        package Entity::Contact;
        use strict;
        use DBEntity;
        use base qw(DBEntity);
1;

#-----------------------------------------

        package Entity::Contact::Collection;
        use strict;
        use DBEntity::Collection;
        use base qw(DBEntity::Collection);
        1;

#-----------------------------------------

        package Entity::Account;
        use strict;
        use DBEntity;
        use base qw(DBEntity);
        use Entity::Passport;
        use Entity::Contact::Collection;

        sub _init_last {
                my $self = shift;
                $self->is_related_to (
                        passport => 'Entity::Passport'
                );
                $self->is_related_to (
                        contacts => 'Entity::Contact::Collection'
                );
        }
        1;

#-----------------------------------------

        package Entity::Account::Collection;
        use strict;
        use DBEntity::Collection;
        use base qw(DBEntity::Collection);
        1;

#-----------------------------------------

Now let's create some SQL tables for our test application (using SQLite):

        create table account (
                account_id serial not null primary key,
                account_login varchar (50) not null
        );
        create table pasport (
                passport_id serial not null primary key,
                passport_serial varchar (50) not null,
                account_id integer
        );
        create table contact (
                contact_id serial not null primary key,
                contact_proto varchar (10) not null,
                contact_address varchar (200) not null,
                account_id integer
        );

And now the funniest part: the script itself:

#-----------------------------------------

        #!/usr/bin/perl

        use strict;
        use Entity::Account;

        # here it doesn`t matter whether there is a user with such a login in
        # the database, if needed we can create it.

        my $account = Entity::Account->fetch_or_create ({login => 'apla'});

        # here fetch_or_create is implicitly activated with the parameters
        # {id => $account->id, serial => 'aabbcc'}

        $account->passport ({serial => 'aabbcc'});

        my $acc_contacts = $account->contacts;

        my $contact = $acc_contacts->new_record ({
                proto => 'email', address => 'apla@localhost'
        });
        $contact->save;
        $acc_contacts->count; 

        1;

AUTHOR ^

Ivan Baktsheev, <apla at the-singlers.us>

BUGS ^

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

SUPPORT ^

ACKNOWLEDGEMENTS ^

COPYRIGHT & LICENSE ^

Copyright 2008-2009 Ivan Baktsheev

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

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