C<lib/MyApp/Controller/Books.pm> would match on the URL
C<http://localhost:3000/books/list> but "C<:Path('/list')>" would match
on C<http://localhost:3000/list>. You can use C<:Args()> to specify
-how many arguments an action should except. See
+how many arguments an action should accept. See
L<Catalyst::Manual::Intro/Action_types> for more information and a few
examples.
<tr>
<td>[% book.title %]</td>
<td>[% book.rating %]</td>
+ <td></td>
</tr>
[% END -%]
</table>
=head1 DATABASE ACCESS WITH DBIx::Class
-Catalyst can be used with virtually any form of datastore available via
-Perl. For example, L<Catalyst::Model::DBI|Catalyst::Model::DBI> can be
-used to access databases through the traditional Perl C<DBI>
-interface. However, most Catalyst applications use some form of
-object-relational mapping (ORM) technology to create objects associated
-with tables in a relational database. Although L<Class::DBI|Class::DBI>
-has been a popular choice in the past, Matt Trout's
-L<DBIx::Class|DBIx::Class> (abbreviated as "DBIC") has rapidly emerged
-as the Perl-based ORM technology of choice. Most new Catalyst
-applications rely on DBIC, as will this tutorial.
+Catalyst can be used with virtually any form of datastore available
+via Perl. For example, L<Catalyst::Model::DBI|Catalyst::Model::DBI>
+can be used to access databases through the traditional Perl C<DBI>
+interface or you can use a model to access files of any type on the
+filesystem. However, most Catalyst applications use some form of
+object-relational mapping (ORM) technology to create objects
+associated with tables in a relational database. Matt Trout's
+L<DBIx::Class|DBIx::Class> (abbreviated as "DBIC") has rapidly emerged
+as the Perl-based ORM technology of choice. Most new Catalyst
+applications rely on DBIx::Class, as will this tutorial.
+Although DBIx::Class has included support for a C<create=dynamic> mode
+to automatically read the database structure every time the
+application starts, it's use is no longer recommended. While it can
+make for "flashy" demos, the use of the C<create=static> mode we use
+below can be implemented just as quickly and provides many advantages
+(such as the ability to add your own methods to the overall DBIC
+framework, a technique that we see in Chapter 4).
-=head2 Create a Dynamic DBIC Model
-Use the C<create=dynamic> model helper option to build a model that
-dynamically reads your database structure every time the application
-starts:
+=head2 Make Sure You Have a Recent Version of the DBIx::Class Model
+
+First, let's be sure we have a recent version of the DBIC helper,
+L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema>, by
+running this command:
+
+ $ perl -MCatalyst::Model::DBIC::Schema -e \
+ 'print "$Catalyst::Model::DBIC::Schema::VERSION\n"'
+ 0.23
+
+If you don't have version 0.23 or higher, please run this command
+to install it directly from CPAN:
+
+ $ sudo cpan Catalyst::Model::DBIC::Schema
+
+And re-run the version print command to verify that you are now at
+0.23 or higher.
+
+
+=head2 Create Static DBIx::Class Schema Files
+
+Use the model helper with the C<create=static> option to read the
+database with
+L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> and
+automatically build the required files for us:
$ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \
- create=dynamic dbi:SQLite:myapp.db
+ create=static components=TimeStamp dbi:SQLite:myapp.db
exists "/home/me/MyApp/script/../lib/MyApp/Model"
exists "/home/me/MyApp/script/../t"
- exists "/home/me/MyApp/script/../lib/MyApp"
- created "/home/me/MyApp/script/../lib/MyApp/Schema.pm"
+ Dumping manual schema for MyApp::Schema to directory /home/me/MyApp/script/../lib ...
+ Schema dump completed.
created "/home/me/MyApp/script/../lib/MyApp/Model/DB.pm"
created "/home/me/MyApp/script/../t/model_DB.t"
+The C<script/myapp_create.pl> command breaks down like this:
+
+=over 4
+
+=item *
+
+C<DB> is the name of the model class to be created by the helper in
+C<lib/MyApp/Model>.
+
+=item *
+
+C<DBIC::Schema> is the type of the model to create.
+
+=item *
+
+C<MyApp::Schema> is the name of the DBIC schema file written to
+C<lib/MyApp/Schema.pm>.
+
+=item *
+
+C<create=static> causes
+L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> to
+load the schema as it runs and then write that information out
+into files.
+
+=item *
+
+C<components=TimeStamp> causes the help to include the
+L<DBIx::Class::TimeStamp|DBIx::Class::TimeStamp> DBIC component.
+
+=item *
+
+And finally, C<dbi:SQLite:myapp.db> is the standard DBI connect string
+for use with SQLite.
+
+=back
+
+If you look in the C<lib/MyApp/Schema.pm> file, you will find that it
+only contains a call to the C<load_namespaces> method. You will also
+find that C<lib/MyApp> contains a C<Schema> subdirectory, which then
+has a subdirectory called "Result". This "Result" subdirectory then
+has files named according to each of the tables in our simple database
+(C<Authors.pm>, C<BookAuthors.pm>, and C<Books.pm>). These three
+files are called "Result Classes" in DBIx::Class nomenclature. Although the
+Result Class files are named after tables in our database, the classes
+correspond to the I<row-level data> that is returned by DBIC (more on
+this later, especially in
+L<Catalyst::Manual::Tutorial::BasicCRUD/EXPLORING THE POWER OF DBIC>).
+
+The idea with the Result Source files created under
+C<lib/MyApp/Schema/Result> by the C<create=static> option is to only
+edit the files below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!>
+warning. If you place all of your changes below that point in the
+file, you can regenerate the automatically created information at the
+top of each file should your database structure get updated.
+
+Also note the "flow" of the model information across the various files
+and directories. Catalyst will initially load the model from
+C<lib/MyApp/Model/DB.pm>. This file contains a reference to
+C<lib/MyApp/Schema.pm>, so that file is loaded next. Finally, the
+call to C<load_namespaces> in C<Schema.pm> will load each of the
+"Result Class" files from the C<lib/MyApp/Schema/Result> subdirectory.
+The final outcome is that Catalyst will dynamically create three
+table-specific Catalyst models every time the application starts (you
+can see these three model files listed in the debug output generated
+when you launch the application).
+
+B<NOTE:> Older versions of
+L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema> use the
+deprecated DBIx::Class C<load_classes> technique instead of the newer
+C<load_namspaces>. For new applications, please try to use
+C<load_namespaces> since it more easily supports a very useful DBIC
+technique called "ResultSet Classes." If you need to convert an
+existing application from "load_classes" to "load_namespaces," you can
+use this process to automate the migration (but first make sure you
+have v0.23 C<Catalyst::Model::DBIC::Schema> as discussed above):
+
+ $ # First delete the existing schema file to disable "compatibility" mode
+ $ rm lib/MyApp/Schema.pm
+ $
+ $ # Then re-run the helper to build the files for "load_namespaces"
+ $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \
+ create=static components=TimeStamp dbi:SQLite:myapp.db
+ $
+ $ # Now convert the existing files over
+ $ cd lib/MyApp/Schema
+ $ perl -MIO::All -e 'for (@ARGV) { my $s < io($_); $s =~ s/.*\n\# You can replace.*?\n//s;
+ $s =~ s/'MyApp::Schema::/'MyApp::Schema::Result::/g; my $d < io("Result/$_");
+ $d =~ s/1;\n?//; "$d$s" > io("Result/$_"); }' *.pm
+ $ cd ../../..
+ $
+ $ # And finally delete the old files
+ $ rm lib/MyApp/Schema/*.pm
+
+The "C<perl -MIO::ALL ...>" script will copy all the customized
+relationship (and other) information below "C<# DO NOT MODIFY>" line
+from the old files in C<lib/MyApp/Schema> to the new files in
+C<lib/MyApp/Schema/Result> (we will be starting to add some
+"customized relationship information in the section below).
The C<script/myapp_create.pl> command breaks down like this:
=back
-B<NOTE:> Although the C<create=dynamic> option to the DBIC helper
-makes for a nifty demonstration, is only really suitable for very
-small applications. After this demonstration, you should almost always
-use the C<create=static> option that we will switch to below.
-
=head1 ENABLE THE MODEL IN THE CONTROLLER
The rating for each book should appear on each row, but the "Author(s)"
column will still be blank (we will fill that in later).
-Also notice in the output of the C<script/myapp_server.pl> that DBIC
-used the following SQL to retrieve the data:
+Also notice in the output of the C<script/myapp_server.pl> that
+DBIx::Class used the following SQL to retrieve the data:
SELECT me.id, me.title, me.rating FROM books me
template -- the wrapper will provide the overall feel of the page.
-=head1 A STATIC DATABASE MODEL WITH DBIx::Class
-
-First, let's be sure we have a recent version of the DBIC helper,
-L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema>, by
-running this command:
-
- $ perl -MCatalyst::Model::DBIC::Schema -e \
- 'print "$Catalyst::Model::DBIC::Schema::VERSION\n"'
- 0.23
-
-If you don't have version 0.23 or higher, please run this command
-to install it directly from CPAN:
-
- $ sudo cpan Catalyst::Model::DBIC::Schema
-
-And re-run the version print command to verify that you are now at
-0.23 or higher.
-
-
-=head2 Create Static DBIC Schema Files
-
-Unlike the previous DBIC section where we had C<create=dynamic>
-automatically discover the structure of the database every time the
-application started, here we will use static schema files for more
-control. This is typical of most "real world" applications.
-
-One option would be to manually create a separate schema file for each
-table in the database. However, let's use the same
-L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> we used
-earlier with C<create=dynamic> to build the static files for us.
-First, let's remove the schema file created earlier:
-
- $ rm lib/MyApp/Schema.pm
-
-Now regenerate the schema using the C<create=static> option:
-
- $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \
- create=static components=TimeStamp dbi:SQLite:myapp.db
- exists "/home/me/MyApp/script/../lib/MyApp/Model"
- exists "/home/me/MyApp/script/../t"
- Dumping manual schema for MyApp::Schema to directory /home/me/MyApp/script/../lib ...
- Schema dump completed.
- exists "/home/me/MyApp/script/../lib/MyApp/Model/DB.pm"
-
-We could have also deleted C<lib/MyApp/Model/DB.pm>, but it would
-have regenerated the same file (note the C<exists> in the output above).
-If you take a look at C<lib/MyApp/Model/DB.pm>, it simply contains
-a reference to the actual schema file in C<lib/MyApp/Schema.pm>
-along with the database connect string.
-
-If you look in the C<lib/MyApp/Schema.pm> file, you will find that it
-is no longer using
-L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> as its base
-class (L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> is
-only being used by the helper to load the schema once and then create
-the static files for us) and C<Schema.pm> only contains a call to the
-C<load_namespaces> method. You will also find that C<lib/MyApp>
-contains a C<Schema> subdirectory, which then has a subdirectory
-called "Result". This "Result" subdirectory then has files named
-according to each of the tables in our simple database (C<Authors.pm>,
-C<BookAuthors.pm>, and C<Books.pm>). These three files are called
-"Result Classes" in DBIC nomenclature. Although the Result Class files
-are named after tables in our database, the classes correspond to the
-I<row-level data> that is returned by DBIC (more on this later,
-especially in
-L<Catalyst::Manual::Tutorial::BasicCRUD/EXPLORING THE POWER OF DBIC>).
-
-The idea with the Result Source files created under
-C<lib/MyApp/Schema/Result> by the C<create=static> option is to only
-edit the files below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!>
-warning. If you place all of your changes below that point in the
-file, you can regenerate the automatically created information at the
-top of each file should your database structure get updated.
-
-Also note the "flow" of the model information across the various files
-and directories. Catalyst will initially load the model from
-C<lib/MyApp/Model/DB.pm>. This file contains a reference to
-C<lib/MyApp/Schema.pm>, so that file is loaded next. Finally, the
-call to C<load_namespaces> in C<Schema.pm> will load each of the
-"Result Class" files from the C<lib/MyApp/Schema/Result> subdirectory.
-The final outcome is that Catalyst will dynamically create three
-table-specific Catalyst models every time the application starts (you
-can see these three model files listed in the debug output generated
-when you launch the application).
-
-B<NOTE:> Older versions of
-L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema> use the
-deprecated DBIC C<load_classes> technique instead of the newer
-C<load_namspaces>. For new applications, please try to use
-C<load_namespaces> since it more easily supports a very useful DBIC
-technique called "ResultSet Classes." If you need to convert an
-existing application from "load_classes" to "load_namespaces," you can
-use this process to automate the migration (but first make sure you
-have v0.23 C<Catalyst::Model::DBIC::Schema> as discussed above):
-
- $ # First delete the existing schema file to disable "compatibility" mode
- $ rm lib/MyApp/Schema.pm
- $
- $ # Then re-run the helper to build the files for "load_namespaces"
- $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \
- create=static components=TimeStamp dbi:SQLite:myapp.db
- $
- $ # Now convert the existing files over
- $ cd lib/MyApp/Schema
- $ perl -MIO::All -e 'for (@ARGV) { my $s < io($_); $s =~ s/.*\n\# You can replace.*?\n//s;
- $s =~ s/'MyApp::Schema::/'MyApp::Schema::Result::/g; my $d < io("Result/$_");
- $d =~ s/1;\n?//; "$d$s" > io("Result/$_"); }' *.pm
- $ cd ../../..
- $
- $ # And finally delete the old files
- $ rm lib/MyApp/Schema/*.pm
-
-The "C<perl -MIO::ALL ...>" script will copy all the customized
-relationship (and other) information below "C<# DO NOT MODIFY>" line
-from the old files in C<lib/MyApp/Schema> to the new files in
-C<lib/MyApp/Schema/Result> (we will be starting to add some
-"customized relationship information in the section below).
-
-
-=head2 Updating the Generated DBIC Result Class Files
+=head2 Updating the Generated DBIx::Class Result Class Files
Let's manually add some relationship information to the auto-generated
Result Class files. (Note: if you are using a database other than
C<Important Note:> Although this tutorial uses plural names for both
the names of the SQL tables and therefore the Result Classes (after
all, C<Schema::Loader> automatically named the Result Classes from the
-names of the SQL tables it found), DBIC users prefer singular names
-for these items. B<Please try to use singular table and DBIC
+names of the SQL tables it found), DBIx::Class users prefer singular
+names for these items. B<Please try to use singular table and DBIC
model/Result Class names in your applications.> This tutorial will
migrate to singular names as soon as possible (patches welcomed).
B<Note that while singular is preferred for the DBIC model, plural is
perfectly acceptable for the names of the controller classes.> After
all, the C<Books.pm> controller operates on multiple books.
-This code defines both a C<has_many> and a C<many_to_many> relationship.
-The C<many_to_many> relationship is optional, but it makes it easier to
-map a book to its collection of authors. Without it, we would have to
-"walk" though the C<book_authors> table as in
-C<$book-E<gt>book_authors-E<gt>first-E<gt>author-E<gt>last_name>
-(we will see examples on how to use DBIC objects in your code soon,
+This code defines both a C<has_many> and a C<many_to_many>
+relationship. The C<many_to_many> relationship is optional, but it
+makes it easier to map a book to its collection of authors. Without
+it, we would have to "walk" though the C<book_authors> table as in
+C<$book-E<gt>book_authors-E<gt>first-E<gt>author-E<gt>last_name> (we
+will see examples on how to use DBIx::Class objects in your code soon,
but note that because C<$book-E<gt>book_authors> can return multiple
authors, we have to use C<first> to display a single author).
-C<many_to_many> allows us to use the shorter
-C<$book-E<gt>authors-E<gt>first-E<gt>last_name>.
-Note that you cannot define a C<many_to_many> relationship without
-also having the C<has_many> relationship in place.
+C<many_to_many> allows us to use the shorter C<$book-E<gt>authors-
+E<gt>first-E<gt>last_name>. Note that you cannot define a
+C<many_to_many> relationship without also having the C<has_many>
+relationship in place.
Then edit C<lib/MyApp/Schema/Result/Authors.pm> and add relationship
information as follows (again, be careful to put in above the C<1;> but
Let's add a new column to our book list page that takes advantage of
the relationship information we manually added to our schema files in
-the previous section. Edit C<root/src/books/list.tt2> and add the
-following code below the existing table cell that contains
-C<book.rating> (IOW, add a new table cell below the existing two
-C<E<lt>tdE<gt>> tags but above the closing C<E<lt>/trE<gt>> and
-C<E<lt>/tableE<gt>> tags):
+the previous section. Edit C<root/src/books/list.tt2> and replace
+the "empty" tabase cell with the following:
...
<td>
If you are still running the development server with C<DBIC_TRACE>
enabled, you should also now see five more C<SELECT> statements in the
debug output (one for each book as the authors are being retrieved by
-DBIC):
+DBIx::Class):
SELECT me.id, me.title, me.rating FROM books me:
SELECT author.id, author.first_name, author.last_name FROM book_authors me
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