=head2 Search results are returned as Rows
Rows of the search from the database are blessed into
-L<DBIx::Class::Row> objects.
+L<Result|DBIx::Class::Manual::ResultClass> objects.
=head1 SETTING UP DBIx::Class
Let's look at how you can set and use your first native L<DBIx::Class> tree.
First we'll see how you can set up your classes yourself. If you want them to
-be auto-discovered, just skip to the next section, which shows you how to use
+be auto-discovered, just skip to the L<next section|/Using
+DBIx::Class::Schema::Loader>, which shows you how to use
L<DBIx::Class::Schema::Loader>.
=head2 Setting it up manually
__PACKAGE__->position_column('rank');
Ordered will refer to a field called 'position' unless otherwise directed. Here you are defining
-the ordering field to be named 'rank'. (NOTE: Insert errors may occur if you use the Ordered
+the ordering field to be named 'rank'. (NOTE: Insert errors may occur if you use the Ordered
component, but have not defined a position column or have a 'position' field in your row.)
Set the table for your class:
size => 16,
is_nullable => 0,
is_auto_increment => 1,
- default_value => '',
},
artist =>
{ data_type => 'integer',
size => 16,
is_nullable => 0,
- is_auto_increment => 0,
- default_value => '',
},
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 => '',
+ default_value => 0,
}
);
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.
+modules such as L<HTML::FormHandler::Model::DBIC> make use of it.
+Also it allows you to create your database tables from your Schema,
+instead of the other way around.
See L<DBIx::Class::Schema/deploy> for details.
See L<DBIx::Class::ResultSource> for more details of the possible column
See L<DBIx::Class::Relationship> for more information about the various types of
available relationships and how you can design your own.
-=head2 Using L<DBIx::Class::Schema::Loader>
+=head2 Using DBIx::Class::Schema::Loader
-This is an external module, and not part of the L<DBIx::Class> distribution.
-Like L<Class::DBI::Loader>, it inspects your database, and automatically creates
-classes for all the tables in your database. Here's a simple setup:
+This module (L<DBIx::Class::Schema::Loader>) is an external module, and not part
+of the L<DBIx::Class> distribution. It inspects your database, and automatically
+creates classes for all the tables in your schema.
- package My::Schema;
- use base qw/DBIx::Class::Schema::Loader/;
+The simplest way to use it is via the L<dbicdump> script from the
+L<DBIx::Class::Schema::Loader> distribution. For example:
+
+ $ dbicdump -o dump_directory=./lib \
+ -o components='["InflateColumn::DateTime"]' \
+ MyApp::Schema dbi:mysql:mydb user pass
+
+If you have a mixed-case database, use the C<preserve_case> option, e.g.:
- __PACKAGE__->loader_options( relationships => 1 );
+ $ dbicdump -o dump_directory=./lib -o preserve_case=1 \
+ -o components='["InflateColumn::DateTime"]' \
+ MyApp::Schema dbi:mysql:mydb user pass
- 1;
+If you are using L<Catalyst>, then you can use the helper that comes with
+L<Catalyst::Model::DBIC::Schema>:
-The actual autoloading process will occur when you create a connected instance
-of your schema below.
+ $ script/myapp_create.pl model MyDB DBIC::Schema MyDB::Schema \
+ create=static moniker_map='{ foo => "FOO" }' dbi:SQLite:./myapp.db \
+ on_connect_do='PRAGMA foreign_keys=ON' quote_char='"'
-See the L<DBIx::Class::Schema::Loader> documentation for more information on its
-many options.
+See L<Catalyst::Helper::Model::DBIC::Schema> for more information on this
+helper.
+
+See the L<DBIx::Class::Schema::Loader> and L<DBIx::Class::Schema::Loader::Base>
+documentation for more information on the many loader options.
=head2 Connecting
{ on_connect_do => \@on_connect_sql_statments }
);
-See L<DBIx::Class::Schema::Storage::DBI/connect_info> for more information about
+See L<DBIx::Class::Storage::DBI/connect_info> for more information about
this and other special C<connect>-time options.
=head3 Via a database handle
my @albums = My::Schema->resultset('Album')->search(
{ artist => 'Bob Marley' },
- { rows => 2, order_by => 'year DESC' }
+ { rows => 2, order_by => { -desc => 'year' } }
);
C<@albums> then holds the two most recent Bob Marley albums.
=head1 NOTES
+=head2 The Significance and Importance of Primary Keys
+
+The concept of a L<primary key|DBIx::Class::ResultSource/set_primary_key> in
+DBIx::Class warrants special discussion. The formal definition (which somewhat
+resembles that of a classic RDBMS) is I<a unique constraint that is least
+likely to change after initial row creation>. However this is where the
+similarity ends. Any time you call a CRUD operation on a row (e.g.
+L<delete|DBIx::Class::Row/delete>,
+L<update|DBIx::Class::Row/update>,
+L<discard_changes|DBIx::Class::Row/discard_changes>,
+etc.) DBIx::Class will use the values of of the
+L<primary key|DBIx::Class::ResultSource/set_primary_key> columns to populate
+the C<WHERE> clause necessary to accomplish the operation. This is why it is
+important to declare a L<primary key|DBIx::Class::ResultSource/set_primary_key>
+on all your result sources B<even if the underlying RDBMS does not have one>.
+In a pinch one can always declare each row identifiable by all its columns:
+
+ __PACKAGE__->set_primary_key(__PACKAGE__->columns);
+
+Note that DBIx::Class is smart enough to store a copy of the PK values before
+any row-object changes take place, so even if you change the values of PK
+columns the C<WHERE> clause will remain correct.
+
+If you elect not to declare a C<primary key>, DBIx::Class will behave correctly
+by throwing exceptions on any row operation that relies on unique identifiable
+rows. If you inherited datasets with multiple identical rows in them, you can
+still operate with such sets provided you only utilize
+L<DBIx::Class::ResultSet> CRUD methods:
+L<search|DBIx::Class::ResultSet/search>,
+L<update|DBIx::Class::ResultSet/update>,
+L<delete|DBIx::Class::ResultSet/delete>
+
+For example, the following would not work (assuming C<People> does not have
+a declared PK):
+
+ my $row = $schema->resultset('People')
+ ->search({ last_name => 'Dantes' })
+ ->next;
+ $row->update({ children => 2 }); # <-- exception thrown because $row isn't
+ # necessarily unique
+
+So instead the following should be done:
+
+ $schema->resultset('People')
+ ->search({ last_name => 'Dantes' })
+ ->update({ children => 2 }); # <-- update's ALL Dantes to have children of 2
+
=head2 Problems on RHEL5/CentOS5
There used to be an issue with the system perl on Red Hat Enterprise
projects / dbsrgits/DBIx-Class.git / blobdiff