Using DAOs without implementing them

Parancoe usare i DAO senza implementarli a cura di Lucio Benfante Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License Roma 2007

What is Parancoe?
A framework (YAFF?)
Yet Another Fucking Framework
A framework aggregation
A tool for developers
Hibernate/JPA + Spring 2 + Spring MVC
Maven 2
+ ...
(write what you are using)

Convention over Configuration DRY (Don't repeat yourself) Don't re-invent the wheel Guidelines

Fun for the developer Main Guideline

mvn archetype:create
-DarchetypeGroupId=org.parancoe
-DarchetypeArtifactId=parancoe-webarchetype
-DarchetypeVersion=0.3.2
-DgroupId= it.jugpadova
-DartifactId= demoapp
-DpackageName= it.jugpadova.demoapp
...at work in seconds!
Starting a new application

...easier with a good IDE

The new application

What I'm able to use? (JUNIOR Programmer)

What I like to use? (SENIOR Developer)

What for the persistent layer? Class.forName( "com.mioDbms.mioDriver" ); Connection con=null; try { con = DriverManager.getConnection ( “ jdbc:...”, “user”, “pass”); ResultSet rs; PreparedStatement ps = conn.prepareStatement( " SELECT * FROM Person WHERE name=? ”); ps. setString (1, "Lucio Benfante"); rs = ps.executeQuery(); while ( rs.next() ) { rs.getString...ecc..ecc.... } rs.close(); ps.close(); stmt.close(); } catch (Exception e){ ... } finally { try { con. close (); } catch( Exception ignoreMe ) {} } JDBC ?

Hibernate <class name="events.Person" table="PERSON"> <id name="id" column="PERSON_ID"> <generator class="native"/> </id> <property name="age"/> <property name="firstname"/> <property name="lastname"/> <set name="events" table="PERSON_EVENT"> <key column="PERSON_ID"/> <many-to-many column="EVENT_ID" class="events.Event"/> </set> </class>
Hibernate?
Mapping in XML?

Hibernate (JPA)
Hibernate (JPA)
Mapping with
annotations!

A “simple” persistent class @Entity() public class Person { private Long id; private String firstName; private String lastName; private Integer version; @Id @GeneratedValue(strategy = GenerationType.AUTO) public Long getId() { ... } public void setId(Long id) { ... } public String getFirstName() { ... } public void setFirstName(String firstName) { ... } public String getLastName() { ... } public void setLastName(String lastName) { ... } @version public Integer getVersion() { ... } public void setVersion() { ... } }

@Entity() public class Person { private Long id; private String firstName; private String lastName; private Integer version; @Id @GeneratedValue(strategy = GenerationType.AUTO) public Long getId() { ... } public void setId(Long id) { ... } public String getFirstName() { ... } public void setFirstName(String firstName) { ... } public String getLastName() { ... } public void setLastName(String lastName) { ... } @version public Integer getVersion() { ... } public void setVersion() { ... } } What I don't like?
Declaration of persistent classes
<hibernate-configuration> <session-factory> <mapping class="it.jugpadova.demoapp.po.Person"/> </session-factory> </hibernate-configuration>
Required fields

The Parancoe Way @Entity() public class Person extends EntityBase { private String firstName; private String lastName; public String getFirstName() { ... } public void setFirstName(String firstName) { ... } public String getLastName() { ... } public void setLastName(String lastName) { ... } } ...auto-discovered!

DAO
DAO
(Data Access Object)

The classic DAO
Interface
Implementation(s)
Factory

Do we need the factory?
Interface
Implementation(s)
Factory
Interface
Implementation(s)
Factory

Common implementation public List<Person> findByLastName (String lastName) { Session session = sessionFactory.openSession(); Transaction tx = null; List<Person> result = null; try { tx = session.beginTransaction(); Query q = session.createQuery( "from Person p where p.lastName = ?”+ “ order by p.lastName” ); q.setString(0, lastName); result = q.list(); tx.commit(); } catch (HibernateException he) { if (tx!=null) tx.rollback(); throw he; } finally { try {session.close();} catch(Exception ignore) {} } return result; }

A minimal DAO Is it possible?
Interface
Implementation(s)
Factory

Parancoe DAO @Dao(entity=Person.class) public interface PersonDao extends GenericDao<Person, Long> { List<Person> findByLastName(String lastName); } Auto-discovered Automatically available in the Spring context people = dao().getPersonDao().findByLastName(“Benfante”);

Some finder examples
List<Person> findBy FirstName And LastName And BirthDate( String firstName, String lastName, Date birthDate);
List<Person> findBy BirthDate OrderBy LastName And FirstName( Date birthDate);
List<Person> findBy OrderBy LastName And FirstName();
Person findByFirstNameAndLastName( String firstName, String lastName);
List<Person> findByLastName( @Compare(CompareType.ILIKE) String lastName);
List<Person> findByLastName(String lastName, @FirstResult int offset, @MaxResults int limit);

Complex queries @Dao(entity=Person.class) public interface PersonDao extends GenericDao<Person, Long> { ... List<Person> searchByPartialUncasedLastName( String partialLastName); ... } @Entity() @NamedQueries({ @NamedQuery( name="Person.searchByPartialUncasedLastName" , query="from Person p”+ ” where lower(p.lastName) like lower(?)”+ ” order by p.lastName") }) public class Person extends EntityBase { ... }

Methods of the base DAO PK create(T newInstance); void createOrUpdate(T o); T read(PK id); void update(T transientObject); void delete(T persistentObject); List<T> findAll(); List<T> searchByCriteria(Criterion... criterion); List<T> searchByCriteria(DetachedCriteria criteria); List<T> searchByCriteria( DetachedCriteria criteria, int firstResult, int maxResults); int deleteAll(); long count();

Informazioni sul JUG Padova
Sito Web
www.jugpadova.it
Mailing List
!Attenzione nuova mailing list su googlegroups
http://groups.google.com/group/jugpadova
Sito Parancoe
www.parancoe.org
Contattami
Lucio Benfante ( [email_address] )
ML Parancoe ( [email_address] )

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Using DAOs without implementing them

by benfante on Oct 22, 2007

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