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| author | Franck Cuny <franck.cuny@gmail.com> | 2013-11-26 10:36:10 -0800 |
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| committer | Franck Cuny <franck.cuny@gmail.com> | 2013-11-26 10:36:10 -0800 |
| commit | 8ddf2e94df70707b458528a437759b96046d3e01 (patch) | |
| tree | d442818d92d3c9c6f7fcdc92857a1228963849a1 /_posts/2009-04-27-a-simple-feed-aggregator-with-modern-perl-part-1.textile | |
| parent | Don't need to use the IP in the makefile. (diff) | |
| download | lumberjaph-8ddf2e94df70707b458528a437759b96046d3e01.tar.gz | |
Huge update.
Moved all posts from textile to markdown. Updated all the CSS and
styles. Added a new page for the resume.
Diffstat (limited to '_posts/2009-04-27-a-simple-feed-aggregator-with-modern-perl-part-1.textile')
| -rw-r--r-- | _posts/2009-04-27-a-simple-feed-aggregator-with-modern-perl-part-1.textile | 153 |
1 files changed, 0 insertions, 153 deletions
diff --git a/_posts/2009-04-27-a-simple-feed-aggregator-with-modern-perl-part-1.textile b/_posts/2009-04-27-a-simple-feed-aggregator-with-modern-perl-part-1.textile deleted file mode 100644 index 01febfa..0000000 --- a/_posts/2009-04-27-a-simple-feed-aggregator-with-modern-perl-part-1.textile +++ /dev/null @@ -1,153 +0,0 @@ ---- -title: A simple feed aggregator with modern Perl - part 1 -category: perl -layout: post ---- - -Following "matt's post":http://www.shadowcat.co.uk/blog/matt-s-trout/iron-man/ about people not blogging enough about Perl, I've decided to try to post once a week about Perl. So I will start by a series of articles about what we call *modern Perl*. For this, I will write a simple feed agregator (using "Moose":http://search.cpan.org/~drolsky/Moose-0.75/lib/Moose.pm, "DBIx::Class":http://search.cpan.org/perldoc?DBIx::Class, "KiokuDB":http://search.cpan.org/perldoc?KiokuDB, some tests, and a basic frontend (with "Catalyst":http://search.cpan.org/perldoc?Catalyst). This article will be split in four parts: - - * the first one will explain how to create a schema using *DBIx::Class* - * the second will be about the aggregator. I will use *Moose** and **KiokuDB* - * the third one will be about writing tests with *Test::Class* - * the last one will focus on *Catalyst* - -The code of these modules will be available on my github account at the -same time each article is published. - -bc. disclaimer: -I'm not showing you how to write the perfect feed aggregator. The purpose of -this series of articles is only to show you how to write a simple aggregator -using modern Perl. - - -h3. The database schema - -We will use a database to store a list of feeds and feed entries. As I don't like, no, wait, I *hate* SQL, I will use an ORM for accessing the database. For this, my choice is *DBIx::Class*, the best ORM available in Perl. - -bc. If you never have used an ORM before, ORM stands for Object Relational -Mapping. It's a SQL to OO mapper that creates an abstract encapsulation of -your databases operations. *DBIx::Class*' purpose is to represent "queries in -your code as perl-ish as possible. - -For a basic aggregator we need: - - * a table for the list of feeds - * a table for the entries - -We will create these two tables using *DBIx::Class*. For this, we first create a Schema module. I use *Module::Setup*, but you can use *Module::Starter* or whatever you want. - -{% highlight bash %} -module-setup MyModel -cd MyModel -vim lib/MyModel.pm -{% endhighlight %} - -{% highlight perl %} -package MyModel; -use base qw/DBIx::Class::Schema/; -__PACKAGE__->load_classes(); -1; -{% endhighlight %} - -So, we have just created a schema class. The *load_classes* method loads all the classes that reside under the *MyModel* namespace. We now create the result class *MyModel::Feed* in *lib/MyModel/Feed.pm*: - -{% highlight perl %} -package MyModel::Feed; -use base qw/DBIx::Class/; -__PACKAGE__->load_components(qw/Core/); -__PACKAGE__->table('feed'); -__PACKAGE__->add_columns(qw/ feedid url /); -__PACKAGE__->set_primary_key('feedid'); -__PACKAGE__->has_many(entries => 'MyModel::Entry', 'feedid'); -1; -{% endhighlight %} - -Pretty self explanatory: we declare a result class that uses the table feed, with two columns: *feedid* and *url*, *feedid* being the primary key. The *has_many* method declares a one-to-many relationship. - -Now the result class *MyModel::Entry* in *lib/MyModel/Entry.pm*: - -{% highlight perl %} -package MyModel::Entry; -use base qw/DBIx::Class/; -__PACKAGE__->load_components(qw/Core/); -__PACKAGE__->table('entry'); -__PACKAGE__->add_columns(qw/ entryid permalink feedid/); -__PACKAGE__->set_primary_key('entryid'); -__PACKAGE__->belongs_to(feed => 'MyModel::Feed', 'feedid'); -1; -{% endhighlight %} - -Here we declare *feed* as a foreign key, using the column name *feedid*. - -You can do a more complex declaration of your schema. Let's say you want to declare the type of your fields, you can do this: - -{% highlight perl %} -__PACKAGE__->add_columns( - 'permalink' => { - 'data_type' => 'TEXT', - 'is_auto_increment' => 0, - 'default_value' => undef, - 'is_foreign_key' => 0, - 'name' => 'url', - 'is_nullable' => 1, - 'size' => '65535' - }, -); -{% endhighlight %} - -*DBIx::Class* also provides hooks for the deploy command. If you are using MySQL, you may need a InnoDB table. In your class, you can add this: - -{% highlight perl %} -sub sqlt_deploy_hook { - my ($self, $sqlt_table) = @_; - $sqlt_table->extra( - mysql_table_type => 'InnoDB', - mysql_charset => 'utf8' - ); -} -{% endhighlight %} - -next time you call deploy on this table, the hook will be sent to *SQL::Translator::Schema*, and force the type of your table to InnoDB, and the charset to utf8. - -Now that we have a *DBIx::Class* schema, we need to deploy it. For this, I always do the same thing: create a *bin/deploy_mymodel.pl* script with the following code: - -{% highlight perl %} -use strict; -use feature 'say'; -use Getopt::Long; -use lib('lib'); -use MyModel; - -GetOptions( - 'dsn=s' => \my $dsn, - 'user=s' => \my $user, - 'passwd=s' => \my $passwd -) or die usage(); - -my $schema = MyModel->connect($dsn, $user, $passwd); -say 'deploying schema ...'; -$schema->deploy; - -say 'done'; - -sub usage { - say - 'usage: deploy_mymodel.pl --dsn $dsn --user $user --passwd $passwd'; -} -{% endhighlight %} - -This script will deploy for you the schema (you need to create the database first if using with mysql). - -Executing the following command: - -{% highlight bash %} -perl bin/deploy_mymodel.pl --dsn dbi:SQLite:model.db -{% endhighlight %} - -generate a *model.db* database so we can work and test it. Now that we got our (really) simple *MyModel* schema, we can start to hack on our aggregator. - -"link to the code":http://github.com/franckcuny/ironman-mymodel/tree/master - -bc. while using *DBIx::Class*, you may want to take a look at the generated -queries. For this, export *DBIC_TRACE=1* in your environment, and -the queries will be printed on STDERR. |
