Translatable for Spring Boot JPA

This module provides an abstract and reusable foundation for supporting translatable (multi-language) entities using Spring Data JPA.
It defines core interfaces, abstract repositories, and a base service class to handle translations with locale-specific logic.

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📦 Package Structure

com.mewebstudio.springboot.jpa.translatable
├── ITranslatable.java
├── ITranslation.java
├── JpaTranslatableRepository.java
├── JpaTranslationRepository.java
└── AbstractTranslatableService.java

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🧩 Interfaces

ITranslatable<ID, T extends ITranslation<ID, ?>>

Represents an entity that supports translations.

public interface ITranslatable<ID, T extends ITranslation<ID, ?>> {
    ID getId();
    List<T> getTranslations();
}

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ITranslation<ID, T>

Represents a translation of an entity in a specific locale.

public interface ITranslation<ID, T> {
    ID getId();
    T getOwner();
    String getLocale();
}

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🗃 Repositories

JpaTranslatableRepository<T, ID, TR>

Generic JPA repository for translatable entities.

@NoRepositoryBean
public interface JpaTranslatableRepository<T extends ITranslatable<ID, TR>, ID, TR extends ITranslation<ID, ?>>
        extends JpaRepository<T, ID> {

    @Query("SELECT COUNT(e) > 0 FROM #{#entityName} e JOIN e.translations t WHERE e.id = :id AND t.locale = :locale")
    boolean existsByIdAndLocale(ID id, String locale);

    @Query("SELECT e FROM #{#entityName} e JOIN e.translations t WHERE e.id = :id AND t.locale = :locale")
    T findByIdAndLocale(ID id, String locale);

    @Query("SELECT DISTINCT e FROM #{#entityName} e JOIN e.translations t WHERE t.locale = :locale")
    List<T> findAllByLocale(String locale);

    Page<T> findAllByLocale(String locale, Pageable pageable);

    @Query("SELECT t FROM #{#entityName} e JOIN e.translations t WHERE e.id = :id")
    List<TR> findTranslationsById(ID id);

    Page<TR> findTranslationsById(ID id, Pageable pageable);

    @Modifying
    @Query("DELETE FROM #{#entityName} e WHERE EXISTS (SELECT 1 FROM e.translations t WHERE t.locale = :locale)")
    int deleteByLocale(String locale);

    @Modifying
    @Query("DELETE FROM #{#entityName} e WHERE e.id = :id AND EXISTS (SELECT 1 FROM e.translations t WHERE t.locale = :locale)")
    int deleteByIdAndLocale(ID id, String locale);
}

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JpaTranslationRepository<T, ID, OWNER>

Generic JPA repository for translation entities.

@NoRepositoryBean
public interface JpaTranslationRepository<T extends ITranslation<ID, OWNER>, ID, OWNER>
        extends JpaRepository<T, ID> {

    @Query("SELECT CASE WHEN COUNT(t) > 0 THEN true ELSE false END FROM #{#entityName} t WHERE t.locale = :locale")
    boolean existsByLocale(String locale);

    @Query("SELECT CASE WHEN COUNT(t) > 0 THEN true ELSE false END FROM #{#entityName} t WHERE t.owner.id = :ownerId AND t.locale = :locale")
    boolean existsByOwnerIdAndLocale(ID ownerId, String locale);

    @Query("SELECT t FROM #{#entityName} t WHERE t.owner.id = :ownerId")
    List<T> findByOwnerId(ID ownerId);

    Page<T> findByOwnerId(ID ownerId, Pageable pageable);

    @Query("SELECT t FROM #{#entityName} t WHERE t.owner.id = :ownerId AND t.locale = :locale")
    T findByOwnerIdAndLocale(ID ownerId, String locale);

    @Query("SELECT t FROM #{#entityName} t WHERE t.name = :name AND t.locale = :locale")
    List<T> findByNameAndLocale(String name, String locale);

    @Modifying
    @Query("DELETE FROM #{#entityName} t WHERE t.locale = :locale")
    int deleteByLocale(String locale);

    @Modifying
    @Query("DELETE FROM #{#entityName} t WHERE t.owner.id = :ownerId AND t.locale = :locale")
    int deleteByOwnerIdAndLocale(ID ownerId, String locale);
}

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🧠 Abstract Service

AbstractTranslatableService<T, ID, TR>

Provides a base service class for business logic operations.

public abstract class AbstractTranslatableService<T extends ITranslatable<ID, TR>, ID, TR extends ITranslation<ID, ?>> {
    protected final JpaTranslatableRepository<T, ID, TR> repository;

    public AbstractTranslatableService(JpaTranslatableRepository<T, ID, TR> repository) {
        this.repository = repository;
    }

    public boolean existsByIdAndLocale(ID id, String locale) {
        return repository.existsByIdAndLocale(id, locale);
    }

    public T findByIdAndLocale(ID id, String locale) {
        return repository.findByIdAndLocale(id, locale);
    }

    public List<T> findAllByLocale(String locale) {
        return repository.findAllByLocale(locale);
    }

    public Page<T> findAllByLocale(String locale, Pageable pageable) {
        return repository.findAllByLocale(locale, pageable);
    }

    public List<TR> findTranslationsById(ID id) {
        return repository.findTranslationsById(id);
    }

    public Page<TR> findTranslationsById(ID id, Pageable pageable) {
        return repository.findTranslationsById(id, pageable);
    }

    @Transactional
    public int deleteByLocale(String locale) {
        return repository.deleteByLocale(locale);
    }

    @Transactional
    public int deleteByIdAndLocale(ID id, String locale) {
        return repository.deleteByIdAndLocale(id, locale);
    }
}

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📥 Installation

for maven users

Add the following dependency to your pom.xml file:

<dependency>
  <groupId>com.mewebstudio</groupId>
  <artifactId>spring-boot-jpa-translatable</artifactId>
  <version>0.1.0</version>
</dependency>

for gradle users

Add the following dependency to your build.gradle file:

implementation 'com.mewebstudio:spring-boot-jpa-translatable:0.1.0'

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📌 Usage

You can extend these interfaces and abstract class to implement your own translatable entities and services:

Translatable Entity Example

@Entity
public class Category implements ITranslatable<Long, CategoryTranslation> {
    @Id private Long id;

    @OneToMany(mappedBy = "owner")
    private List<CategoryTranslation> translations;

    // getters...
}

Translation Entity Example

@Entity
public class CategoryTranslation implements ITranslation<Long, Category> {
    @Id private Long id;

    @ManyToOne
    private Category owner;

    private String locale;
    private String name;

    // getters...
}

Translatable Repository Example

public interface CategoryRepository extends JpaTranslatableRepository<Category, String, CategoryTranslation> {
    // Custom query methods can be added here
}

Translation Repository Example

public interface CategoryTranslationRepository extends JpaTranslationRepository<CategoryTranslation, String, Category> {
    // Custom query methods can be added here
}

Translatable Service Example

@Service
@Slf4j
public class CategoryService extends AbstractTranslatableService<Category, String, CategoryTranslation> {
    private final CategoryRepository categoryRepository;
    private final CategoryTranslationRepository categoryTranslationRepository;

    /**
     * Constructs a new CategoryService.
     *
     * @param categoryRepository            the category repository
     * @param categoryTranslationRepository the category translation repository
     */
    public CategoryService(CategoryRepository categoryRepository, CategoryTranslationRepository categoryTranslationRepository) {
        super(categoryRepository);
        this.categoryRepository = categoryRepository;
        this.categoryTranslationRepository = categoryTranslationRepository;

        log.debug("CategoryService initialized with repository: {}", categoryRepository);
        Objects.requireNonNull(categoryRepository, "CategoryRepository cannot be null");
    }

    // Custom business logic methods can be added here
}    

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🛠 Requirements

• Java 17+
• Spring Boot 3.x
• Spring Data JPA

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🔁 Other Implementations

Spring Boot JPA Translatable (Kotlin Maven Package)

💡 Example Implementations

Spring Boot JPA Translatable - Java Implementation

Spring Boot JPA Translatable - Kotlin Implementation

📃 License

MIT © mewebstudio