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Tag Archives: JPA

JPA: Determining the Owning Side of a Relationship

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When using the Java Persistence API (JPA) it is often necessary to create relationships between two entities.  These relationships are defined within the data model (think database) through the use of foreign keys and within our object model (think Java) using annotations to indicate associations. When defining relationships or associations within the object model a common task is identifying the ...

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JPA – Hibernate – Type mapping on package level

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When we are finally mature enough to use some custom types mapping in JPA, we usually stuck with some provider specific solution, because JPA itself doesn’t define any mechanism for doing it. Let me show you an example of custom type mapping definition for one of the JPA providers – Hibernate. Suppose that we use Joda Money in our project, ...

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JPA 2.0 Criteria Query with Hibernate

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Criteria Query has been introduced in JPA 2.0. With the help of criteria queries you can write your queries in a type-safe way. Before criteria queries, developers had to write queries through the construction of object-based query definitions. There might be chances of incorrect syntax while building the queries. The criteria query API provides feature to create structured and nested ...

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JPA and CMT – Why Catching Persistence Exception is Not Enough?

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Being in EJB and JPA world using CMT (Container Managed Transactions) is very comfortable. Just define few annotations to demarcate transaction boundary (or use the defaults) and that’s it – no fiddling with manual begin, commit or rollback operations. One way to rollback your transaction is to throw non-application exception (or application exception with rollback = true) from your EJB’s ...

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Types of Entity Managers: Application-managed EntityManager

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JPA specification defines few types of EntityManagers / Persistence Contexts. We can have: extended and transactional-scoped EntityManagers, container-managed or application-managed EntityManagers. JTA or resource-local EntityManager, Besides the above distinction, we also have two main contexts in which EntityManager / Persistence Context can exist – Java EE and Java SE. Not every option is available for Java EE and not every ...

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Bidirectional @OneToMany / @ManyToOne association

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One of goals in programming is representing of models from real world. Very often an application need to model some relationship between entities. In the last article about Hibernate associations I have described rules of setting up the “one to one” relationship. Today I’m going to show you how to setup bidirectional “one to many” and “many to one” association. ...

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Bidirectional @OneToOne primary key association

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It’s time to continue articles about Hibernate. The last one was dedicated to unidirectional @OneToOne association. So today I will show you how to obtain bidirectional @OneTonOne primary key association. An example from this tutorial based on previous article. Let’s get started. I will work with the same tables which I have created previously. In order to setup a bidirectional ...

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EasyCriteria 2.0 – JPA Criteria should be easy

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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 ...

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Spring Data JPA and pagination

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Let us start with the classic JPA way to support pagination. Consider a simple domain class – A ‘Member’ with attributes first name, last name. To support pagination on a list of members, the JPA way is to support a finder which takes in the offset of the first result(firstResult) and the size of the result(maxResults) to retrieve, this way: ...

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Database Encryption Using JPA Listeners

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I recently had to add database encryption to a few fields and discovered a lot of bad advice out there. Architectural Issues The biggest problem is architectural. If your persistence manager quietly handles your encryption then, by definition, your architecture demands a tight and unnecessary binding between your persistence and security designs. You can’t touch one without also touching the ...

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