Category Archives: English

Hello, how are you?

We are happy to announce that EasyCriteria is now on Maven Repository.

To use it just add the line below in the pom.xml:

<dependency>
	<groupId>uaihebert.com</groupId>
	<artifactId>EasyCriteria</artifactId>
	<version>2.1.0</version>
</dependency>

Simple and easy. The version 2.1.0 was released to adapt the pom.xml to the Maven requirements.

I hope you like this news! =D

http://easycriteria.uaihebert.com

Hello, how are you?

It has been a long time since my last post, but I was not doing nothing during this time.

In the post today we will see about the new version of the framework named EasyCriteria. At the end of this post we will see what is to come here in the blog.

Unfortunately the JPA criteria has a huge problem that is its verbosity. Why not make easier? Thinking like this that EasyCriteria framework were born and now it is on version 2.0.

To do a simple JPQL with the JPA Criteria the following code would be needed:

CriteriaQuery<Person> criteriaQuery = criteriaBuilder.createQuery(Person.class);
Root<Person> root = criteriaQuery.from(Person.class);
criteriaQuery.select(root);
TypedQuery<Person> query = entityManager.createQuery(criteriaQuery);
query.getResultList();

Notice all the code needed to do the query: select p from Person p.

Check below how easy it is to do the same Criteria with EasyCriteria:

EasyCriteria<Person> easyCriteria = EasyCriteriaFactory.createQuery(entityManager, Person.class);
easyCriteria.getResultList();

The difference between version 1.0 and the 2.0 version is in the reduction of methods into generic methods. To compare methods with =, >=, <, <=, and other methods just use the API like below:

easyCriteria.andGreaterThan("hairSize", 10.4f); // >

easyCriteria.andGreaterOrEqualTo("height", 11.00d); // >=

easyCriteria.andLessThan("totalBooksOwned", 30L); // <

easyCriteria.andLessOrEqualTo("firstJobDate", firstJobDate); // <=

easyCriteria.andJoinEquals("dogs", "age", 15); // =

easyCriteria.andJoinStringIn("dogs", "name", names); // value in (x, i, z, ...)

easyCriteria.andJoinStringLike("dogs", "name", "%y");

One of the ideals of the EasyCriteria framework is to expose the lower number possible of API to the user. Thinking like this, EasyCriteria added the “OR” condition to its API without new classes.

Take a look below to see how to do queries with OR:

select s from Song s where s.id = 1 or s.length = 40 or s.artist = 'Group 1 Crew'

easyCriteria.orEquals("id", 1).orEquals("length", 40).orEquals("artist", "Group 1 Crew");

Another type of OR could be done:

select s from Song s where (s.id = 1) or (s.id = 2) or (s.length = 40) or (s.artist = 'Group 1 Crew')

easyCriteria.orEquals("id", 1, 2).orEquals("length", 40).orEquals("artist", "Group 1 Crew");

And it is possible to do complexes queries cases like:

select s from Song s where (s.totalDownloads = 20 or s.weight = 10.00) and (s.price = 20.00 or s.type = :type)

easyCriteria.orEquals(1, "totalDownloads", 20L).orEquals(1, "weight", 10.00f).orEquals(2, "price", 20.00d).orEquals(2, "type", SongType.PRAISE);

The idea of index were added to the API to be used with a group of OR. The first OR group is composed of “totalDownloads” and “weight”, the second group has “price” and “type” as elements.

As default index the value 1 is always used. The criteria above could be written as:

easyCriteria.orEquals("totalDownloads", 20L).orEquals("weight", 10.00f).orEquals(2, "price", 20.00d).orEquals(2, "type", SongType.PRAISE);

It is possible create a query to do the inverse of the query above, AND separated by OR:

select s from Song s where (s.id = 1 and s.name = 'Sing Out') or (s.id = 2 and s.name = 'Alive')

easyCriteria.addAndSeparatedByOr(1, "id", 1).addAndSeparatedByOr(1, "name", "Sing Out").addAndSeparatedByOr(2, "id", 2).addAndSeparatedByOr(2, "name", "Alive");

That is all for today, I hope you like the new version. It will take a long time to consider this framework complete. Helping with the OR functionality I could count with João Neves (http://about.me/joaonevesfilho) and Sasaki (http://curriculum.rodrigosasaki.com/).

Here it is possible to see the framework official page: http://easycriteria.uaihebert.com/. And the best, it is open source (http://code.google.com/p/easy-criteria/).

Other fact about the framework is that it is 100% covered with tests using Cobertura. EasyCriteria was tested with OpenJPA, EclipseLink and Hibernate. Now it is time to ask for your help. It was found bugs in the tested implementations; it would be wonderful if you spare 5 minutes of your time voting in the bugs. With your vote the bug could be corrected faster.

EclipseLink: https://bugs.eclipse.org/bugs/show_bug.cgi?id=386354
OpenJPA: https://issues.apache.org/jira/browse/OPENJPA-2333
Hibernate: https://hibernate.onjira.com/browse/HHH-7985

What is to come in the blog? It took so much time for me to write this post because I am finishing my first book. If God’s will, the book will be released in March.

In this pause of new posts here, I have studied a lot of Maven and I want my next post to be about a mini book about a basic Maven and full web applications. Yes, I said “applications” in plural. [=

See you soon. \o_

Hello, how are you?

Today we will see about JPA: what is the persistence.xml file used for, how to create an entity, mapping easy and complex ids, creating relationships between the entities, automatically entity persistence and more.

Today we will see:

• Page 02: Reasons that led to the creation of JPA
• Page 03: What is JPA? What is a JPA Implementation?
• Page 04: What is the persistence.xml file used for? And its configurations?
• Page 05: Entity definitions. What are the Logic and Physical annotations?
• Page 06: Id Generation: Definition, using Identity or Sequence
• Page 07: Id Generation: TableGenerator and Auto
• Page 08: Simple Composite Key
• Page 09: Complex Composite Key
• Page 10: How to get an EntityManager
• Page 11: Mapping two or more tables in one entity
• Page 12: Mapping Hierarchy: MappedSuperclass
• Page 13: Mapping Hierarchy: Single Table
• Page 14: Mapping Hierarchy: Joined
• Page 15: Mapping Hierarchy: Table per Concrete Class
• Page 16: Pros/Cons of each hierarchy mapping approach
• Page 17: Embedded Objects
• Page 18: ElementCollection – how to map a list of values into a class
• Page 19: OneToOne unidirectional and bidirectional
• Page 20: OneToMany/ManyToOne unidirectional and bidirectional
• Page 21: ManyToMany unidirectional and bidirectional
• Page 22: ManyToMany with extra fields
• Page 23: How the Cascade functionality works? How should a developer use the OrphanRemoval? Handling the org.hibernate.TransientObjectException
• Page 24: How to delete an entity with relationships. How to know which relationships are raising the exception
• Page 25: Creating one EntityManagerFactory by application
• Page 26: Understanding how the Lazy/Eager option works
• Page 27: Handling the “cannot simultaneously fetch multiple bags” error

Just one more observation: I will not create a PDF file of this post. Just to create this material I already take several hours of code formatting, images production, translate all text to the English language and texts adjusts in this blog page. I am sorry, but there is no way to create a PDF file, maybe sometime later but I will not promise.

Hello, how are you?

This post will talk about the new functionalities of EasyCriteria.

EasyCriteria is a tool (Open Source) to make easier the JPA Criteria code for any kind of JPA implementation. EasyCriteria has 100% of coverage on its tests with JUnit and it is tested with: Hibernate, OpenJPA and EclipseLink.

If you want to understand the Criteria ideal and how to apply it to your code check this post: EasyCriteria – An easy way to use the JPA Criteria

The new EasyCriteria functionalities are:

• Join with conditions
• Query Pagination

Now it is possible to do a Join and add parameters to it:

EntityManager em = emf.createEntityManager();
EasyCriteria<Person> easyCriteria = EasyCriteriaFactory.createQueryCriteria(em, Person.class);

easyCriteria.innerJoin("dogs", Dog.class);
easyCriteria.whereJoinEquals("dogs", "name", "Dark");
easyCriteria.whereJoinStringNotIn("dogs", "name", names); // names is a List<String>
easyCriteria.whereJoinStringLike("dogs", "name", "M%");
easyCriteria.whereJoinListIsEmpty("dogs", "cars");
easyCriteria.whereJoinAttributeIsNull("dogs", "nickName");
easyCriteria.whereJoinStringBetween("dogs", "name", "A", "L");

The query can be paginated:

EasyCriteria<Dog> easyCriteria = EasyCriteriaFactory.createQueryCriteria(getEntityManager(), Dog.class);
easyCriteria.setFirstResult(0);
easyCriteria.setMaxResults(5);

This new version also has 100% of code coverage.

Click here to download the code of this post with EasyCriteria. With this code you can test EasyCriteria as you like.

In the project page (http://easycriteria.uaihebert.com/) you will find all documentation.

If you have any doubt, just post it.

See you soon! \o_