如何在会话缓存中跨实体与 JPA 保持数据同步？

Question

我正在研究如何使会话缓存中的数据保持同步。我有以下示例：

@Table (name = "language")
@Entity
public class Language
{
    @Id
    @Column (name = "key", unique = true, nullable = false)
    private String key;

    @Column (name = "name", unique = true, nullable = false)
    private String name;

    @OneToMany (mappedBy = "language", cascade = { CascadeType.DETACH, CascadeType.REFRESH, CascadeType.REMOVE })
    private Set<Translation> translations;
}


@Table (name = "translation")
@Entity
public class Translation 
{
    @Id
    @GeneratedValue (strategy = GenerationType.SEQUENCE)
    private Long id;

    @ManyToOne(optional = false)
    private Language language;

    @ManyToOne (optional = false)
    @JoinColumn(referencedColumnName = "key")
    private TranslatableEntity translatable;

    @Column(name = "value")
    private String value;
}


@Table (name = "translatable")
@Entity
public class Translatable
{
    @Id
    @GeneratedValue (strategy = GenerationType.SEQUENCE)
    private Long id;

    @NotNull
    @Size (max = 255)
    @Column (name = "key", unique = true, nullable = false)
    private String key;

    @OneToMany (mappedBy = "translatable", cascade = { CascadeType.DETACH, CascadeType.REFRESH, CascadeType.REMOVE, CascadeType.PERSIST })
    @MapKey (name = "language")
    private Map<Language, Translation> translations;
}

基本上我是这样的：

// Print current translations for en language
Language language = languageRepository.getOne("en");
printTranslations(language);

// Add new translatable object with translation for english language
Translatable translatable = new Translatable();
translatable.addTranslation("en", "...")
translatableRepository.saveAndFlush(translatable)

// Again print translations for en language
// This still prints outdated information
language = languageRepository.getOne("en");
printTranslations(language);

所以我的问题是如何保持数据的一致性。

当 inserting/removing 一个带有一些翻译的新翻译时，语言实例中的翻译列表不会在会话缓存中更新。我找不到任何满意的答案。这个最接近：.

谢谢

Answer 1

JPA 不会为您维护双向关系的两端。一级缓存的目的是在事务实体中只加载一次。

这为您提供了解决问题的两种选择：

自己维护关系的两边，例如通过实现Translatable.add方法来更新Language.translations和Translation.language
通过在调用 languageRepository.getOne("en")

language

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