如何在会话缓存中的实体之间保持数据与 JPA 同步？

Question

我试图找出如何在会话缓存中保持数据同步。我举了以下例子:

@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;
}

所以基本上我会:

// 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// This still prints outdated information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。

当插入/删除带有某些翻译的新翻译时，语言实例中的翻译列表不会在会话缓存中更新。对此我找不到任何满意的答案。这是最接近的一个:在JPA中删除孩子时保持实体关系同步。

谢谢。

Answer 1

JPA不会为您维护双向关系的双方。一级缓存的目的是在一个事务中实体只被加载一次。

这给了你两个解决问题的选择:

>

自己维护关系的双方，例如通过实现＜code＞Translatable。添加方法，使其更新语言。翻译和翻译。语言

在调用< code > language repository . get one(" en ")之前，通过驱逐或关闭会话(即事务)来强制重新加载< code>language