3 DBIx::Class::Manual::SchemaIntro - Introduction to DBIx::Class::Schema
7 This document describes how to set up DBIx::Class using the recommended
12 First, you should create your base schema class, which inherits from
13 L<DBIx::Class::Schema>:
16 use base qw/DBIx::Class::Schema/;
18 In this class you load your resultsource ("table", "model") classes, which
19 we will define later, using the load_classes() method. You can specify which
20 classes to load manually:
22 # load My::Schema::Album and My::Schema::Artist
23 __PACKAGE__->load_classes(qw/ Album Artist /);
25 Or load classes by namespace:
27 # load My::Schema::Album, My::Schema::Artist and My::OtherSchema::LinerNotes
28 __PACKAGE__->load_classes(
30 'My::Schema' => qw/ Album Artist /,
31 'My::OtherSchema' => qw/ LinerNotes /
35 Or let your schema class load all classes in its namespace automatically:
38 __PACKAGE__->load_classes();
40 Next, create each of the classes you want to load as specified above:
42 package My::Schema::Album;
43 use base qw/DBIx::Class/;
45 Load any components required by each class with the load_components() method.
46 This should consist of "Core" plus any additional components you want to use.
47 For example, if you use SQLite and want serial/auto-incrementing primary keys:
49 __PACKAGE__->load_components(qw/ PK::Auto::SQLite Core /);
51 C<PK::Auto> classes exist for many databases; see
52 L<DBIx::Class::PK::Auto> for more information.
54 Set the table for your class:
56 __PACKAGE__->table('album');
58 Add columns to your class:
60 __PACKAGE__->add_columns(qw/ albumid artist title /);
62 Accessors are created for each column automatically, so My::Schema::Album will
63 have albumid(), artist() and title() methods.
65 Define a primary key for your class:
67 __PACKAGE__->set_primary_key('albumid');
69 If you have a multi-column primary key, just pass a list instead:
71 __PACKAGE__->set_primary_key( qw/ albumid artistid / );
73 You can define relationships for any of your classes. L<DBIx::Class> will
74 automatically fill in the correct namespace, so if you want to say
75 "a My::Schema::Album object belongs to a My::Schema::Artist object" you do not
76 need to include the namespace when declaring the relationship:
78 __PACKAGE__->belongs_to('artist' => 'Artist');
80 That's all you need in terms of setup.
84 In your application code, you should first create a connected schema object:
86 my $schema = My::Schema->connect( $dsn, $user, $password, $attrs );
88 You can create as many different schema instances as you need. So if you have
89 a second database you want to access:
91 my $other_schema = My::Schema->connect( $dsn, $user, $password, $attrs );
93 Note that L<DBIx::Class::Schema> does not cache connnections for you. If you
94 use multiple connections, you need to do this manually.
96 The simplest way to get a record is by primary key:
98 my $schema = My::Schema->connect( ... );
99 my $album = $schema->resultset('Album')->find(14);
101 This will run a C<SELECT> with C<albumid = 14> in the C<WHERE> clause,
102 and return an instance of C<My::Schema::Album> that represents this
103 row. Once you have that row, you can access and update columns:
105 $album->name('Physical Graffiti');
106 my $title = $album->title; # holds 'Physical Graffiti'
108 If you prefer, you can use the C<set_column> and C<get_column>
111 $album->set_column('title', 'Presence');
112 $title = $album->get_column('title');
114 You use C<update> to commit your changes to the database:
118 If needed, you can throw away your local changes like this:
120 $album->discard_changes() if $album->is_changed();
122 As you can see, C<is_changed> allows you to check if there are local
123 changes to your object.
125 =head2 Adding and removing rows
127 To create a new record in the database, you can use the C<create>
128 method. It returns an instance of C<My::Schema::Album> that can be
129 used to access the data in the new record:
131 my $new_album = $schema->resultset('Album')->create({
132 title => 'Wish You Were Here',
133 artist => 'Pink Floyd'
136 Now you can add data to the new record:
138 $new_album->label('Capitol');
139 $new_album->year('1975');
142 Likewise, you can remove it from the database like this:
146 You can also remove records without or retrieving first. This
147 operation takes the same kind of arguments as a search.
149 # Delete all of Falco's albums
150 $schema->resultset('Album')->delete({ artist => 'Falco' });
152 =head2 Finding your objects
154 L<DBIx::Class> provides a few different ways to retrieve data from
155 your database. Here's one example:
157 # Find all of Santana's albums
158 my $rs = $schema->resultset('Album')->search({ artist => 'Santana' });
160 In scalar context, as above, C<search> returns a
161 L<DBIx::Class::ResultSet> object. It can be used to peek at the first
162 album returned by the database:
164 my $album = $rs->first;
167 Or, you can loop over the albums and update each one:
169 while (my $album = $rs->next) {
170 print $album->artist . ' - ' . $album->title;
175 For more information on what you can do with a
176 L<DBIx::Class::ResultSet>, see L<DBIx::Class::ResultSet/METHODS>.
178 In list context, the C<search> method returns all of the matching
181 # Fetch immediately all of Carlos Santana's albums
182 my @albums = @{ $schema->resultset('Album')->search(
183 { artist => 'Carlos Santana' }
185 foreach my $album (@albums) {
186 print $album->artist . ' - ' . $album->title;
189 We also provide a handy shortcut for doing a C<LIKE> search:
191 # Find albums whose artist starts with 'Jimi'
192 my $rs = MyApp::DB::Album->search_like({ artist => 'Jimi%' });
194 Or you can provide your own handmade C<WHERE> clause, like:
196 # Find Peter Frampton albums from the year 1986
197 my $where = 'artist = ? AND year = ?';
198 my @bind = ( 'Peter Frampton', 1986 );
199 my $rs = $schema->resultset('Album')->search_literal( $where, @bind );
201 The preferred way to generate complex queries is to provide a
202 L<SQL::Abstract> construct to C<search>:
204 my $rs = $schema->resultset('Album')->search({
205 artist => { '!=', 'Janis Joplin' },
206 year => { '<' => 1980 },
207 albumid => [ 1, 14, 15, 65, 43 ]
210 This results in something like the following C<WHERE> clause:
212 WHERE artist != 'Janis Joplin'
214 AND albumid IN (1, 14, 15, 65, 43)
216 For more examples of complex queries, see
217 L<DBIx::Class::Manual::Cookbook>.
219 The search can also be modified by passing another hash with
222 my @albums = $schema->resultset('Album')->search(
223 { artist => 'Bob Marley' },
224 { rows => 2, order_by => 'year DESC' }
227 C<@albums> then holds the two most recent Bob Marley albums.
229 For a complete overview of the available attributes, see
230 L<DBIx::Class::ResultSet/ATTRIBUTES>.
236 =item * L<DBIx::Class::Manual::Cookbook>
238 =item * L<DBIx::Class::Manual::FAQ>