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 result_source ("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 To execute some sql statements on every connect you can pass them to your schema after the connect:
98 $schema->storage->on_connect_do(\@on_connect_sql_statments);
100 The simplest way to get a record is by primary key:
102 my $schema = My::Schema->connect( ... );
103 my $album = $schema->resultset('Album')->find(14);
105 This will run a C<SELECT> with C<albumid = 14> in the C<WHERE> clause,
106 and return an instance of C<My::Schema::Album> that represents this
107 row. Once you have that row, you can access and update columns:
109 $album->name('Physical Graffiti');
110 my $title = $album->title; # holds 'Physical Graffiti'
112 If you prefer, you can use the C<set_column> and C<get_column>
115 $album->set_column('title', 'Presence');
116 $title = $album->get_column('title');
118 You use C<update> to commit your changes to the database:
122 If needed, you can throw away your local changes like this:
124 $album->discard_changes() if $album->is_changed();
126 As you can see, C<is_changed> allows you to check if there are local
127 changes to your object.
129 =head2 Adding and removing rows
131 To create a new record in the database, you can use the C<create>
132 method. It returns an instance of C<My::Schema::Album> that can be
133 used to access the data in the new record:
135 my $new_album = $schema->resultset('Album')->create({
136 title => 'Wish You Were Here',
137 artist => 'Pink Floyd'
140 Now you can add data to the new record:
142 $new_album->label('Capitol');
143 $new_album->year('1975');
146 Likewise, you can remove it from the database like this:
150 You can also remove records without or retrieving first. This
151 operation takes the same kind of arguments as a search.
153 # Delete all of Falco's albums
154 $schema->resultset('Album')->delete({ artist => 'Falco' });
156 =head2 Finding your objects
158 L<DBIx::Class> provides a few different ways to retrieve data from
159 your database. Here's one example:
161 # Find all of Santana's albums
162 my $rs = $schema->resultset('Album')->search({ artist => 'Santana' });
164 In scalar context, as above, C<search> returns a
165 L<DBIx::Class::ResultSet> object. It can be used to peek at the first
166 album returned by the database:
168 my $album = $rs->first;
171 Or, you can loop over the albums and update each one:
173 while (my $album = $rs->next) {
174 print $album->artist . ' - ' . $album->title;
179 For more information on what you can do with a
180 L<DBIx::Class::ResultSet>, see L<DBIx::Class::ResultSet/METHODS>.
182 In list context, the C<search> method returns all of the matching
185 # Fetch immediately all of Carlos Santana's albums
186 my @albums = @{ $schema->resultset('Album')->search(
187 { artist => 'Carlos Santana' }
189 foreach my $album (@albums) {
190 print $album->artist . ' - ' . $album->title;
193 We also provide a handy shortcut for doing a C<LIKE> search:
195 # Find albums whose artist starts with 'Jimi'
196 my $rs = $schema->resultset('Album')->search_like({ artist => 'Jimi%' });
198 Or you can provide your own handmade C<WHERE> clause, like:
200 # Find Peter Frampton albums from the year 1986
201 my $where = 'artist = ? AND year = ?';
202 my @bind = ( 'Peter Frampton', 1986 );
203 my $rs = $schema->resultset('Album')->search_literal( $where, @bind );
205 The preferred way to generate complex queries is to provide a
206 L<SQL::Abstract> construct to C<search>:
208 my $rs = $schema->resultset('Album')->search({
209 artist => { '!=', 'Janis Joplin' },
210 year => { '<' => 1980 },
211 albumid => [ 1, 14, 15, 65, 43 ]
214 This results in something like the following C<WHERE> clause:
216 WHERE artist != 'Janis Joplin'
218 AND albumid IN (1, 14, 15, 65, 43)
220 For more examples of complex queries, see
221 L<DBIx::Class::Manual::Cookbook>.
223 The search can also be modified by passing another hash with
226 my @albums = $schema->resultset('Album')->search(
227 { artist => 'Bob Marley' },
228 { rows => 2, order_by => 'year DESC' }
231 C<@albums> then holds the two most recent Bob Marley albums.
233 For a complete overview of the available attributes, see
234 L<DBIx::Class::ResultSet/ATTRIBUTES>.
240 =item * L<DBIx::Class::Manual::Cookbook>
242 =item * L<DBIx::Class::Manual::FAQ>