About EntityManager

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Forum
18

multi EntityManager with Spring Boot, but 'Too many persistable types (>10)

I'm trying to use two EntityManager with Spring Boot, but no luck with 'Too many persistable types (>10) - exceeds evaluation limit' at second database. My purpose is converting database (converting model entity. same class name but different package). Single application with Spring-Boot 2.1.8
Manual
17

JPA Lifecycle Events

(added to the EntityManager). @PostPersist - after storing a new entity in the database (during commit or ... - when an entity is identified as modified by the EntityManager. @PostUpdate - after updating an entity in ... the EntityManager. @PostRemove - after deleting an entity from the database (during commit or flush). An entity
Manual
17

Query Parameters in JPA

getCountryByName(EntityManager em, String name) { TypedQuery query = em.createQuery ... Country getCountryByName(EntityManager em, String name) { TypedQuery query = em ... without parameters: public Country getCountryByName(EntityManager em, String name) { TypedQuery
Tutorial
17

Step 3: Define an EJB Session Bean

; import java.util.List; import javax.ejb.Stateless; import javax.persistence.EntityManager; import ... class GuestDao { // Injected database connection: @PersistenceContext private EntityManager ... ). Prepares an EntityManager automatically and injects it into the em field (because it is annotated
Tutorial
17

Step 3: Define an EJB Session Bean

.persistence.EntityManager; import javax.persistence.PersistenceContext; import javax.persistence.TypedQuery ... : @PersistenceContext private EntityManager em; // Stores a new guest: public void persist(Guest guest ... shown in the next step). Prepares an EntityManager automatically and injects it into the em field
Issue
17

InternalException during EntityManager.find()

InternalException during EntityManager.find()
Manual
14

JPA Metamodel API

by the EntityManager's getMetamodel method (both methods are equivalent). For example, given an EntityManager, em, a Metamodel instance can be obtained by: Metamodel metamodel = em.getMetamodel
Result
14

ObjectDB Object Database Features

entity object cache (per EntityManager). L2 shared entity data cache (per EntityManagerFactory ... availability and fault tolerance. Online Backup Online backup by a simple query on an EntityManager
Manual
14

SELECT clause (JPQL / Criteria API)

The ability to retrieve managed entity objects is a major advantage of JPQL. For example, the following query returns Country objects that become managed by the EntityManager em: TypedQuery ... are not associated with an EntityManager and changes to them when a transaction is active are not
Tutorial
14

Step 4: Add a Servlet Class

().getAttribute("emf"); EntityManager em = emf.createEntityManager(); try ... : The EntityManagerFactory is retrieved from the application scope attribute, and then an EntityManager