Rewriting https://github.com/deathman92/localized project for my own needs. Now support Hibernate 5.6.5.Final. Other versions weren't tested.

@Localized

Internationalization (i18n) is so boring. There is no one single best practice. And they are all just a pain in the ass when your String is no more a String but something like a Map<Locale, String>. Bye JSR-303 validation annotations. So let's try to find a solution which keeps i18n simple, without polluting your domain model and keep the type of the properties:

@Entity
class Book {

    @Id
    private int id;

    private Author author;

    @Localized
    private String title;

}

@Localized annotates the property Book.title as a translatable String. This looks promising. But how does Hibernate know which Locale is relevant?

LocaleResolver

That's the job of a LocaleResolver implementation. Implement or choose one from the package com.twigcodes.hibernate.localized.locale_resolver. There are several ways of registering the LocaleResolver:

Specify the fully qualified class name in the hibernate property hibernate.listeners.localized.locale_resolver:

<property name="hibernate.listeners.localized.locale_resolver">SpringLocaleResolver</property>

LocalizedIntegrator.setLocaleResolver(new SpringLocaleResolver());

Gradle

repositories {
 mavenCentral()
}

dependencies {
 compile("com.twigcodes.hibernate:localized:1.0.1")
}

Maven

<dependency>
  <groupId>com.twigcodes.hibernate</groupId>
  <artifactId>localized</artifactId>
  <version>1.0.1</version>
</dependency>

Concept

The mechanism is straight forward: A @Localized field is backed by many LocalizedProperty entities (each locale one entity). Hibernate's event system provides infrastructure for replacing and storing transparently the @Localized fields.This concept increases the Session communication. Do not use @Localized when performance is a concern.

Some concepts of original realisation have been remade.

Type of field 'value' changed back to @Lob.
Reference by type is replaced with refenrence by table name to simplify inserting by SQL.
If no translation found for locale default value of field is used.

Limitations

I18n happens around Hibernate's POST_LOAD, POST_UPDATE, POST_INSERT and POST_DELETE events. In between nothing happens. I.e. you have to fix the locale at Session begin (before the first POST_LOAD event on a localized entity). If you change the locale during a session you have to synchronize the entities with Session.flush() and Session.refresh(Object).

Dependencies

org.hibernate:hibernate-core:5.6.5.Final
org.springframework:spring-context:5.3.17

Other versions weren't tested.

Disclaimer

There is no practical knowledge about stability, scalability or performance. Use it at your own risk!

Licence

MIT

wpcfan/localized