Top "Orm" questions

Hibernate vs JPA vs JDO - pros and cons of each?

I'm familiar with ORM as a concept, and I've even used nHibernate several years ago for a .NET project; however, …

java hibernate orm jpa jdo

mappedBy reference an unknown target entity property

I am having an issue in setting up a one to many relationship in my annotated object. I have the …

java hibernate orm hibernate-annotations

Doctrine 2 ArrayCollection filter method

Can I filter out results from an arrayCollection in Doctrine 2 while using lazy loading? For example, // users = ArrayCollection with User …

orm doctrine-orm lazy-loading arraycollection

Specifying an Index (Non-Unique Key) Using JPA

How do you define a field, eg email as having an index using JPA annotations. We need a non-unique key …

java hibernate orm jpa datanucleus

What is Persistence Context?

I am new to the Java world and JPA. I was studying JPA and came across many new terms like …

java jpa orm persistence

The EntityManager is closed

[Doctrine\ORM\ORMException] The EntityManager is closed. After I get a DBAL exception when inserting data, EntityManager closes and I'm …

symfony orm doctrine-orm entitymanager

Error : java.lang.NoSuchMethodError: org.objectweb.asm.ClassWriter.<init>(I)V

I am developing a small Spring application. I have to store the details of the student information in the database. …

java spring hibernate orm java-bytecode-asm

Doctrine2: Best way to handle many-to-many with extra columns in reference table

I'm wondering what's the best, the cleanest and the most simply way to work with many-to-many relations in Doctrine2. Let's …

php orm model doctrine doctrine-orm

What is referencedColumnName used for in JPA?

In JPA there is an attribute called referencedColumnName that can be set on @JoinColumn, @PrimaryKeyJoinColumn what is the idea behind …

hibernate jpa orm eclipselink openjpa

How to remove entity with ManyToMany relationship in JPA (and corresponding join table rows)?

Let's say I have two entities: Group and User. Every user can be member of many groups and every group …

java hibernate jpa orm