About entity
JPA Persistable Types
Explains how JPA manages types, including entity classes, embeddable classes, primitive types, wrappers, string, date, enum, collections and maps.... types, which are: User defined classes - Entity classes, Mapped superclasses, Embeddable classes. Simple ... defined). Note : Only instances of entity classes can be stored in the database directly. Other persistable types ...
Storing JPA Entity Objects
Explains how to use JPA to store (persist) entity objects in the database. New entity objects can be stored in the database either explicitly by invoking the persist persist(entity) EntityManager's method Make an instance managed and ... Referenced Embedded Objects Referenced Entity Objects Cascading Persist Global Cascading ...
Retrieving JPA Entity Objects
Explains how to use JPA to retrieve entity objects from the database.... The persistence context serves as a cache of retrieved entity objects. If a requested entity object is not found in the persistence context a new object is ...
Deleting JPA Entity Objects
Explains how to use JPA to delete (remove) entity objects from the database. Existing entity objects can be deleted from the database either explicitly by invoking the remove remove(entity) EntityManager's method Remove the entity instance. See JavaDoc Reference Page... method or ...
Defining a JPA Entity Class
Shows how to define a JPA entity class in order to store objects in the database.... objects in the database using JPA we need to define an entity class . A JPA entity class is a POJO (Plain Old Java Object) class, i.e. an ordinary Java ...
Step 2: Entity Class and Persistence Unit
Explains how to define a JPA entity class and a persistence unit (persistence.xml) in a NetBeans Java EE 6 web application.... in an ObjectDB database using JPA we need to define an entity class: Open the [New Entity Class] dialog box, e.g. by right clicking the project node (in the ...
Step 2: Entity Class and Persistence Unit
Explains how to define a JPA entity class and a persistence unit (persistence.xml) in a NetBeans Spring MVC web application project.... in an ObjectDB database using JPA we need to define an entity class: Open the [New Entity Class] dialog box, e.g. by right clicking the project node (in the ...
JPA Primary Key
Explains how to define and use primary keys in JPA, including composite and embedded primary keys. Every entity object that is stored in the database has a primary key. Once assigned, the primary key cannot be modified. It represents the entity object as long as it exists in the database. As an object ... This page covers the following topics: Entity Identification Automatic Primary Key ...
Detached Entity Objects
Explains detached entity objects and how to work with detached objects in JPA, including merging them into an EntityManager. Detached entity objects are objects in a special state in which they are not managed ... represent objects in the database. Compared to managed entity objects, detached objects are limited in functionality: ... do not accept detached objects (e.g. lock lock(entity, lockMode) EntityManager's method Lock an entity instance ...
