So, you are bored with SQL, and want a native Perl interface for your
database? Or you've been doing this for a while with L<Class::DBI>,
-and think there's a better way? You've come to the right place. Let's
-look at how you can set and use your first native L<DBIx::Class> tree.
+and think there's a better way? You've come to the right place.
+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
+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 L<DBIx::Class::Loader>.
+you how to use L<DBIx::Class::Schema::Loader>.
=head2 Setting it up manually
-First, you'll need a base class. It should inherit from DBIx::Class
-like this:
+First, you should create your base schema class, which inherits from
+L<DBIx::Class::Schema>:
- package MyApp::DB;
- use base qw/DBIx::Class/;
+ package My::Schema;
+ use base qw/DBIx::Class::Schema/;
-You will also want to load some of L<DBIx::Class>'s components.
-L<DBIx::Class::Core> provides a good basic set. In addition you'll
-have to use either L<DBIx::Class::Schema> or L<DBIx::Class::DB> We'll
-use C<DB> in this introduction, since it involves less magic.
-L<Schema> is mostly useful if you want to use multiple database
-connections.
+In this class you load your result_source ("table", "model") classes, which
+we will define later, using the load_classes() method. You can specify which
+classes to load manually:
- __PACKAGE__->load_components(qw/Core DB/);
+ # load My::Schema::Album and My::Schema::Artist
+ __PACKAGE__->load_classes(qw/ Album Artist /);
-If you want serial/auto-incremental primary keys, you'll need to add
-the apropriate component for your db as well, for example. The
-L<DBIx::Class::PK::Auto> modules help L<DBIx::Class> keep up with
-newly generated keys in auto increment database fields.
+Or load classes by namespace:
- __PACKAGE__->load_components(qw/PK::Auto::SQLite Core DB/);
+ # load My::Schema::Album, My::Schema::Artist and My::OtherSchema::LinerNotes
+ __PACKAGE__->load_classes(
+ {
+ 'My::Schema' => [qw/ Album Artist /],
+ 'My::OtherSchema' => [qw/ LinerNotes /]
+ }
+ );
-Once you've loaded the components, it's time to set up your connection:
+Or let your schema class load all classes in its namespace automatically:
- __PACKAGE__->connection('dbi:SQLite:/home/me/myapp/my.db');
+ # load My::Schema::*
+ __PACKAGE__->load_classes();
-This method is similar to the normal L<DBI>, and can take username,
-password, and L<DBI> attribute hash as well as the DSN.
+Next, create each of the classes you want to load as specified above:
-With that out of the way, we can define our first table class:
+ package My::Schema::Album;
+ use base qw/DBIx::Class/;
- package MyApp::DB::Album;
- use base qw/MyApp::DB/;
+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:
-Then we specify which table it uses,
+ __PACKAGE__->load_components(qw/ PK::Auto Core /);
- __PACKAGE__->table('album');
+C<PK::Auto> is supported for many databases; see
+L<DBIx::Class::Storage::DBI> for more information.
-and specify which columns it has.
+Set the table for your class:
- __PACKAGE__->add_columns(qw/albumID artist title label year/);
+ __PACKAGE__->table('album');
-This will automatically create accessors for each of the columns, so
-that you can read/update the values in rows you've retrieved.
+Add columns to your class:
-Also, you need to tell it which column is the primary key:
+ __PACKAGE__->add_columns(qw/ albumid artist title /);
- __PACKAGE__->set_primary_key('albumID');
+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 such as:
-If you have multiple primary keys, just pass a list instead.
+ __PACKAGE__->add_columns(albumid =>
+ { accessor => 'album',
+ data_type => 'integer',
+ 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 => '',
+ }
+ );
-That's pretty much all you need for a basic setup. If you have more
-advanced needs like using more than one database connection for the
-same class, see L<DBIx::Class::Schema>.
+Most of this data isn't yet used directly by DBIx::Class, 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.
-=head2 Using L<DBIx::Class::Loader>
+See L<DBIx::Class::ResultSource> for more details of the possible column
+attributes.
-This is an additional class, and not part of the L<DBIx::Class>
+Accessors are created for each column automatically, so My::Schema::Album will
+have albumid() (or album(), when using the accessor), artist() and title()
+methods.
+
+Define a primary key for your class:
+
+ __PACKAGE__->set_primary_key('albumid');
+
+If you have a multi-column primary key, just pass a list instead:
+
+ __PACKAGE__->set_primary_key( qw/ albumid artistid / );
+
+Define relationships that the class has with any other classes by using
+either C<belongs_to> to describe a column which contains an ID of another
+table, or C<has_many> to make a predefined accessor for fetching objects
+that contain this tables foreign key in one of their columns:
+
+ __PACKAGE__->has_many('albums', 'My::Schema::Artist', 'album_id');
+
+More information about the various types of relationships available, and
+how you can design your own, can be found in L<DBIx::Class::Relationship>.
+
+
+=head2 Using L<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:
+and automatically creates classes for all the tables in your database.
+Here's a simple setup:
- package MyApp::DB;
- use DBIx::Class::Loader;
+ package My::Schema;
+ use base qw/DBIx::Class::Schema::Loader/;
- my $loader = DBIx::Class::Loader->new(
- dsn => 'dbi:SQLite:/home/me/myapp/my.db',
- namespace => 'MyApp::DB'
- );
+ __PACKAGE__->load_from_connection(
+ connect_info = [ 'dbi:SQLite:/home/me/myapp/my.db' ]
+ );
- 1;
+ 1;
-This should be equivalent to the manual in the section above.
-L<DBIx::Class::Loader> takes lots of other options. For more
+This should be equivalent to the manual setup in the section above.
+L<DBIx::Class::Schema::Loader> takes lots of other options. For more
information, consult its documentation.
+=head2 Connecting
+
+L<DBIx::Class::Schema::Loader> already contains the connection info for the
+database, so to get started all you need to do is create an instance of your
+class:
+
+ my $schema = My::Schema->new();
+
+To connect to your manually created Schema, you also need to provide the
+connection details:
+
+ my $schema = My::Schema->connect('dbi:SQLite:/home/me/myapp/my.db');
+
+You can create as many different schema instances as you need. So if you have
+a second database you want to access:
+
+ my $other_schema = My::Schema->connect( $dsn, $user, $password, $attrs );
+
+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 pass them to your schema after the connect:
+
+ $schema->storage->on_connect_do(\@on_connect_sql_statments);
+
=head2 Basic usage
-Once you've defined the basic classes, you can start interacting with
-your database. The simplest way to get a column is by primary key:
+Once you've defined the basic classes, either manually or using
+L<DBIx::Class::Schema::Loader>, you can start interacting with your database.
+
+To access your database using your $schema object, you can fetch a L<DBIx::Class::Manual::Glossary/"ResultSet">
+representing each of your tables by calling the ->resultset method.
- my $albumID = 14;
- my $album = MyApp::DB::Album->find($albumID);
+The simplest way to get a record is by primary key:
-This will run a select with C<albumID = 14> in the C<WHERE> clause,
-and return an instance of C<MyApp::DB::Artist> that represents this
-row. Once you have that row, you can access and update columns:
+ my $album = $schema->resultset('Album')->find(14);
- $album->title('Physical Graffiti');
- my $title = $album->title; # $title holds 'Physical Graffiti'
+This will run a C<SELECT> with C<albumid = 14> in the C<WHERE> clause,
+and return an instance of C<My::Schema::Album> that represents this
+row. Once you have that row, you can access and update columns:
+
+ $album->title('Physical Graffiti');
+ my $title = $album->title; # $title holds 'Physical Graffiti'
If you prefer, you can use the C<set_column> and C<get_column>
accessors instead:
- $album->set_column('title', 'Presence');
- $title = $album->get_column('title');
+ $album->set_column('title', 'Presence');
+ $title = $album->get_column('title');
-Just like with L<Class::DBI>, you do an C<update> to commit your
+Just like with L<Class::DBI>, you call C<update> to commit your
changes to the database:
- $album->update;
+ $album->update;
-If needed, you can drop your local changes instead like this:
+If needed, you can throw away your local changes like this:
- $album->discard_changes if $album->is_changed;
+ $album->discard_changes if $album->is_changed;
As you can see, C<is_changed> allows you to check if there are local
changes to your object.
=head2 Adding and removing rows
To create a new record in the database, you can use the C<create>
-method from L<DBIx::Class::Row>. It returns a
-L<DBIx::Class::ResultSet> object that can be used to access the data
-in the new record.
+method. It returns an instance of C<My::Schema::Album> that can be
+used to access the data in the new record:
- my $new_album = MyApp::DB::Album->create({
- title => 'Wish You Were Here',
- artist => 'Pink Floyd'
- });
+ my $new_album = $schema->resultset('Album')->create({
+ title => 'Wish You Were Here',
+ artist => 'Pink Floyd'
+ });
Now you can add data to the new record:
- $new_album->label('Capitol');
- $new_album->year('1975');
+ $new_album->label('Capitol');
+ $new_album->year('1975');
+ $new_album->update;
-Likewise, you can remove if from the database like this:
+Likewise, you can remove it from the database like this:
- $new_album->delete;
+ $new_album->delete;
-or even without retrieving first. This operation takes the same kind
-of arguments as a search.
+You can also remove records without retrieving them first, by calling
+delete directly on a ResultSet object.
- MyApp::DB::Album->delete({ artist => 'Falco' });
+ # Delete all of Falco's albums
+ $schema->resultset('Album')->search({ artist => 'Falco' })->delete;
=head2 Finding your objects
L<DBIx::Class> provides a few different ways to retrieve data from
-your database. The simplest looks something like this:
+your database. Here's one example:
+
+ # Find all of Santana's albums
+ my $rs = $schema->resultset('Album')->search({ artist => 'Santana' });
+
+In scalar context, as above, C<search> returns a
+L<DBIx::Class::ResultSet> object. It can be used to peek at the first
+album returned by the database:
+
+ my $album = $rs->first;
+ print $album->title;
+
+You can loop over the albums and update each one:
- my $album = MyApp::DB::Album->search( artist => 'Santana' );
+ while (my $album = $rs->next) {
+ print $album->artist . ' - ' . $album->title;
+ $album->year(2001);
+ $album->update;
+ }
+
+Or, you can update them all at once:
+
+ $rs->update({ year => 2001 });
+
+For more information on what you can do with a
+L<DBIx::Class::ResultSet>, see L<DBIx::Class::ResultSet/METHODS>.
+
+In list context, the C<search> method returns all of the matching
+rows:
-Note that all the search methods return a L<DBIx::Class::ResultSet>
-object in scalar context or a list containing all the records in list
-context.
+ # Fetch immediately all of Carlos Santana's albums
+ my @albums = $schema->resultset('Album')->search(
+ { artist => 'Carlos Santana' }
+ );
+ foreach my $album (@albums) {
+ print $album->artist . ' - ' . $album->title;
+ }
We also provide a handy shortcut for doing a C<LIKE> search:
- my $album = MyApp::DB::Album->search_like( artist => 'Jimi%' );
+ # Find albums whose artist starts with 'Jimi'
+ my $rs = $schema->resultset('Album')->search_like({ artist => 'Jimi%' });
-Or you can provide your own handmade C<WHERE> clause, like:
-
- my $album = MyApp::DB::Album->search_literal( 'artist = ?', 'Peter Frampton' );
+Or you can provide your own C<WHERE> clause, like:
+
+ # Find Peter Frampton albums from the year 1986
+ my $where = 'artist = ? AND year = ?';
+ my @bind = ( 'Peter Frampton', 1986 );
+ my $rs = $schema->resultset('Album')->search_literal( $where, @bind );
The preferred way to generate complex queries is to provide a
L<SQL::Abstract> construct to C<search>:
- my $album = MyApp::DB::Album->search({
- artist => { '!=', 'Janis Joplin' },
- year => { '<' => 1980 },
- id => [ 1, 14, 15, 65, 43 ]
- });
+ my $rs = $schema->resultset('Album')->search({
+ artist => { '!=', 'Janis Joplin' },
+ year => { '<' => 1980 },
+ albumid => [ 1, 14, 15, 65, 43 ]
+ });
+
+This results in something like the following C<WHERE> clause:
-For more examples of complex searches, see
+ WHERE artist != 'Janis Joplin'
+ AND year < 1980
+ AND albumid IN (1, 14, 15, 65, 43)
+
+For more examples of complex queries, see
L<DBIx::Class::Manual::Cookbook>.
The search can also be modified by passing another hash with
attributes:
- my $album = MyApp::DB::Album->search(
- { artist => 'Bob Marley' },
- { page => 1, rows => 2, order_by => 'year' }
- );
+ my @albums = My::Schema->resultset('Album')->search(
+ { artist => 'Bob Marley' },
+ { rows => 2, order_by => 'year DESC' }
+ );
+
+C<@albums> then holds the two most recent Bob Marley albums.
For a complete overview of the available attributes, see
L<DBIx::Class::ResultSet/ATTRIBUTES>.
projects / dbsrgits/DBIx-Class.git / blobdiff