=head1 THE DBIx::Class WAY
Here are a few simple tips that will help you get your bearings with
-DBIx::Class.
+DBIx::Class.
=head2 Tables become Result classes
=head2 It's all about the ResultSet
So, we've got some ResultSources defined. Now, we want to actually use those
-definitions to help us translate the queries we need into handy perl objects!
+definitions to help us translate the queries we need into handy perl objects!
Let's say we defined a ResultSource for an "album" table with three columns:
"albumid", "artist", and "title". Any time we want to query this table, we'll
SELECT albumid, artist, title FROM album;
Would be retrieved by creating a ResultSet object from the album table's
-ResultSource, likely by using the "search" method.
+ResultSource, likely by using the "search" method.
DBIx::Class doesn't limit you to creating only simple ResultSets -- if you
wanted to do something like:
SELECT title FROM album GROUP BY title;
-You could easily achieve it.
+You could easily achieve it.
-The important thing to understand:
+The important thing to understand:
- Any time you would reach for a SQL query in DBI, you are
+ Any time you would reach for a SQL query in DBI, you are
creating a DBIx::Class::ResultSet.
=head2 Search is like "prepare"
Next, create each of the classes you want to load as specified above:
package My::Schema::Result::Album;
- use base qw/DBIx::Class/;
-
-Load any components required by each class with the load_components() method.
-This should consist of "Core" plus any additional components you want to use.
-For example, if you want serial/auto-incrementing primary keys:
+ use base qw/DBIx::Class::Core/;
- __PACKAGE__->load_components(qw/ PK::Auto Core /);
+Load any additional components you may need with the load_components() method,
+and provide component configuration if required. For example, if you want
+automatic row ordering:
-C<PK::Auto> is supported for many databases; see L<DBIx::Class::Storage::DBI>
-for more information.
+ __PACKAGE__->load_components(qw/ Ordered /);
+ __PACKAGE__->position_column('rank');
Set the table for your class:
Add columns to your class:
- __PACKAGE__->add_columns(qw/ albumid artist title /);
+ __PACKAGE__->add_columns(qw/ albumid artist title rank /);
Each column can also be set up with its own accessor, data_type and other pieces
of information that it may be useful to have -- just pass C<add_columns> a hash:
is_auto_increment => 0,
default_value => '',
},
- title =>
+ title =>
{ data_type => 'varchar',
size => 256,
is_nullable => 0,
is_auto_increment => 0,
default_value => '',
+ },
+ rank =>
+ { data_type => 'integer',
+ size => 16,
+ is_nullable => 0,
+ is_auto_increment => 0,
+ default_value => '',
}
);
DBIx::Class doesn't directly use most of this data yet, but various related
modules such as L<DBIx::Class::WebForm> make use of it. Also it allows you to
create your database tables from your Schema, instead of the other way around.
-See L<SQL::Translator> for details.
+See L<DBIx::Class::Schema/deploy> for details.
See L<DBIx::Class::ResultSource> for more details of the possible column
attributes.
make a predefined accessor for fetching objects that contain this Table's
foreign key:
- __PACKAGE__->has_many('albums', 'My::Schema::Result::Artist', 'album_id');
+ # in My::Schema::Result::Artist
+ __PACKAGE__->has_many('albums', 'My::Schema::Result::Album', 'artist');
See L<DBIx::Class::Relationship> for more information about the various types of
available relationships and how you can design your own.
=head2 Connecting
-To connect to your Schema, you need to provide the connection details. The
-arguments are the same as for L<DBI/connect>:
+To connect to your Schema, you need to provide the connection details or a
+database handle.
+
+=head3 Via connection details
+
+The arguments are the same as for L<DBI/connect>:
my $schema = My::Schema->connect('dbi:SQLite:/home/me/myapp/my.db');
Note that L<DBIx::Class::Schema> does not cache connections for you. If you use
multiple connections, you need to do this manually.
-To execute some sql statements on every connect you can add them as an option in
+To execute some SQL statements on every connect you can add them as an option in
a special fifth argument to connect:
my $another_schema = My::Schema->connect(
See L<DBIx::Class::Schema::Storage::DBI/connect_info> for more information about
this and other special C<connect>-time options.
+=head3 Via a database handle
+
+The supplied coderef is expected to return a single connected database handle
+(e.g. a L<DBI> C<$dbh>)
+
+ my $schema = My::Schema->connect (
+ sub { Some::DBH::Factory->connect },
+ \%extra_attrs,
+ );
+
=head2 Basic usage
Once you've defined the basic classes, either manually or using
$album->set_column('title', 'Presence');
$title = $album->get_column('title');
-Just like with L<Class::DBI>, you call C<update> to commit your changes to the
-database:
+Just like with L<Class::DBI>, you call C<update> to save your changes to the
+database (by executing the actual C<UPDATE> statement):
$album->update;
returns an instance of C<My::Schema::Result::Album> that can be used to access the data
in the new record:
- my $new_album = $schema->resultset('Album')->create({
+ my $new_album = $schema->resultset('Album')->create({
title => 'Wish You Were Here',
artist => 'Pink Floyd'
});
=head2 Problems on RHEL5/CentOS5
-There is a problem with slow performance of certain DBIx::Class
-operations in perl-5.8.8-10 and later on RedHat and related systems, due
-to a bad backport of a "use overload" related bug. The problem is in the
-Perl binary itself, not in DBIx::Class. If your system might suffer this
-problem, you will see a warning on startup, with some options as to what
-to do about it. This problem was eliminated in the perl-5.8.8-15.el5_2.1
-package which was issued in September 2008.
+There used to be an issue with the system perl on Red Hat Enterprise
+Linux 5, some versions of Fedora and derived systems. Further
+information on this can be found in L<DBIx::Class::Manual::Troubleshooting>
=head1 SEE ALSO
projects / dbsrgits/DBIx-Class.git / blobdiff