Frameworks - Hibernate Q&As Archives

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02: Understanding Hibernate proxy objects and avoiding potential pitfalls

Q. How does hibernate support lazy loading? A. Hibernate uses a proxy object to support lazy loading. Basically as soon as you reference a child or lookup object via the accessor/getter …

03: Identifying and fixing NonUniqueObjectException in Hibernate

NonUniqueObjectException is thrown when there is an object already associated with the session with the same id (primary key) (i.e. a duplicate). It is important to understand the concept of a …

04: Identifying and fixing LazyInitializationException in Hibernate

LazyInitializationException is thrown when an object becomes detached, and if you try to access associated (i.e. proxied) object(s) of a detached object.

Q. What is a detached object in Hibernate?

When …

05: Debugging Hibernate & handling 4 common issues

#1. Enable Logging in your log4j.xml, log4j.properties, or myapp-logback.xml

In the log4j.properties file, you can enable Hibernate SQL logging as shown below

log4j.logger.org.hibernate.SQL=DEBUG
log4j.logger.org.hibernate.type=trace

1 2	log4j.logger.org

…

07: Hibernate mistakes – accessing objects outside of a transaction

Hibernate does require the same EntityManager to be available in order to lazily load objects. If you have no EntityManager, then you have no knowledge of the datastore. Once the transaction …

08: Hibernate automatic dirty checking of persistent objects and handling detached objects

Q1. What do you understand by automatic dirty checking in Hibernate? A1. Dirty checking is a feature of hibernate that saves time and effort to update the database when states of …

09: Hibernate entities with auditable, soft delete & optimistic locking fields

There are certain generic columns that database tables have like Auto generated identity columns. Auditing columns like createdDtTm, createdBy, modifiedDtTm, and modifiedBy. Soft delete or logical delete flags like inactive ‘Y’ …

10: Spring, JavaConfig (i.e @Configuration), JPA & Hibernate by example

Example #1 Wiring JDBC Datasource


@Configuration
@ImportResource("application.yml")
public class AppConfig
{
    @Autowired
    private Environment environment;

    @Bean
    public DriverManagerDataSource datasource() {
        DriverManagerDataSource ds = new DriverManagerDataSource();
        ds.setDriverClassName(environment.getRequiredProperty("spring.datasource.driver-class-name"));
        ds.setUrl(environment.getRequiredProperty("spring.datasource.url"));
        ds.setUsername(environment.getRequiredProperty("spring.datasource.username"));
        ds.setPassword(environment.getRequiredProperty("spring.datasource.password"));
        return ds;

…

11: Hibernate dependency jars and plugins

Here is a sample maven pom.xml snippets containing the dependency jars.

....
<hibernate.version>4.1.3.Final</hibernate.version>
<hibernate-jpa-2.0-api.version>1.0.1.Final</hibernate-jpa-2.0-api.version>
<hibernate-validator-annotation-processor>4.2.0.Final</hibernate-validator-annotation-processor>
<hibernate-validator.version>4.3.0.Final</hibernate-validator.version>

....

<hibernate.version

…

Blog Archives

02: Understanding Hibernate proxy objects and avoiding potential pitfalls

03: Identifying and fixing NonUniqueObjectException in Hibernate

04: Identifying and fixing LazyInitializationException in Hibernate

Q. What is a detached object in Hibernate?

05: Debugging Hibernate & handling 4 common issues

#1. Enable Logging in your log4j.xml, log4j.properties, or myapp-logback.xml

07: Hibernate mistakes – accessing objects outside of a transaction

08: Hibernate automatic dirty checking of persistent objects and handling detached objects

09: Hibernate entities with auditable, soft delete & optimistic locking fields

10: Spring, JavaConfig (i.e @Configuration), JPA & Hibernate by example

11: Hibernate dependency jars and plugins

12: Hibernate custom data type : Blob type example

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