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Doctrine ORM in Joomla!Herman Peeren, YeprJ & Beyond, June 1, 2013Jooctrine

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Remember Flipper?

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On the menu:1. What is Object Relational Mapping?2. Doctrine2 ORM -> Joomla! extensions3. possibilities to improve Joomla!’s core?

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What is ORM?Object Relational Mapping

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Mapping some knight-objects...... to their proper tables

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• model:• JTable (& other) objects• JTableContent• WeblinksTableWeblink• JTableUser, JUser• collection• object / item (entity)• relational database:• tables• #__content• #__weblinks• #__users• table• rowSimple “mapping” in Joomla!

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• 1NF = only atomic fieldsBUT:• user could have multiple- (email) addresses,- skills,- friends,- partners...

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Mapping Layer• layer between the objects and the tables• mapping associations

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Association mapping• one to one• one to many• many to manyIn relational databasetraversed with foreign keys + joinsYou get the whole thing together

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Objects traversal:// Listing streets per customerforeach ($customers as $customer){echo $customer->getName().’<br />’;foreach ($customer->getAdresses() as $address) // Lazy Loading{echo ‘<li>’.$address->getStreet()</li>;}}

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Collections• ArrayCollection class inDoctrineCommon (Collection interface)• Lazy vs eager loading• Transitive persistence (cascades)

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Splitting in layers:• domain layer (the entities)• mapping layer(with persistence API)• data layer (the database)

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Transparent persistence• the entities (objects) themselves don’t know anythingabout persistence• N.B.: JTable = Active Record= entities are table rows with CRUD

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Unit of Workupdate ofcustomer name, address and creditlimitwith Doctrine:// this is done in memory, in the customer repository:$customer->setName(‘Richy’);$customer->setCreditlimit(10000);// $address is an address-object, that has been set before$customer->setAddress($address);// and the changes are made permanent in the database$em->flush();

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Defining the mappingIn Doctrine the mapping can be definedin 4 ways:• annotations• xml• yml• phpThe mapping information is stored in ClassMetadata in-stances (which are cached in a production environment)

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ORM Designervisual mapping tool (not Free!):http://www.orm-designer.com/

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Command line tool• db-schema generation!• direction: from mapping info to db,not the other way around!!!• and entity-generation

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Inheritance mapping• concrete table inheritance(a.k.a.: mapped superclass)• class table inheritance(a.k.a.: joined table inheritance)• one table inheritance(a.k.a.: single table inheritance)Zie Fowler’s PEAA(images 2 next pages)

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Concrete Table inheritance

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Class Table inheritance

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NoSql-mapping• Doctrine ODM (a.o. MongoDB)• easy switching ORM - ODM• mix for instance MySql and MongoDB:http://docs.doctrine-project.org/projects/doctrine-mongodb-odm/en/latest/cookbook/mapping-classes-to-orm-and-odm.html

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DQLDoctrine Query Language• looks like SQL,but querying the entities, not the tables• querybuilder// Query addresses per customer with fetch-join: eager loading$query = $em->createQuery(“SELECT c, aFROM Customer c JOIN c.addresses a”);$customers = $query->getResult();

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Doctrine2 documentation• http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/index.html

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Using Doctrine2 ORMfor Joomla! extensions• installation via composerhttp://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/configura-tion.html• Also see articles Paul de Raay:http://www.paulderaaij.nl/tag/doctrine/• Adding a prefix (see cookbook):http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/cookbook/sql-table-prefixes.html

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Jooctrine-package version 0.1for easy use, including:• latest Doctrine2• + bootstrap.php• + jooctrinemodel.php• + prefix listenerdownload from jooctrine.orgwill be installed in libraries/doctrine(for easy plug and play; to be continued)

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// using Joomla config-info$joomlaConfig = JFactory::getConfig();$dbParams = array( ‘driver’ => ‘pdo_mysql’, ‘path’ => ‘database.mysql’, ‘charset’ => ‘utf8’, ‘host’ => $joomlaConfig->get(‘host’), ‘dbname’ => $joomlaConfig->get(‘db’), ‘user’ => $joomlaConfig->get(‘user’), ‘password’ => $joomlaConfig->get(‘password’) );// idem: the prefix$prefix = $joomlaConfig->get(‘dbprefix’);extend model from JooctrineModelentity manager: $this->em• I use 1 model in a component (my “domainmodel”)• this model is used with several views

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What I came acrossmaking a Joomla-extension with this:• it is easy to use Doctrine in Joomla! Great possibilities!BUT:• change a basic building block and a lot changes• many things don’t function anymore ...• singular or plural view is essential in Joomla!• also: 1 table row = 1 entity with atomic fields

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Change a basic building blockand ...

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possibilities to improveJoomla!’s core?• hierarchies, nested associations without JTableNested• fields can be objects, objects can be collections• UCM: mapping and structure separated• stucture in model; no HMVC mis-use• better OOP, beyond the db-normalisation paradigm• easier Language associations (Flipper always returns)

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Questions?

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Thank you!more info and download:www.jooctrine.orgcontact:herman@yepr.nlwww.hermanpeeren.nlwww.yepr.euillustrations:www.redcheeksfactory.com