如果已插入具有相同id的数据，则不会更新JPA自动增量

Question

我必须用自动递增的方式分类

@Id //The unique id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;

@Column(unique = true)
private String name;

@OneToMany(cascade = {CascadeType.ALL}, fetch = FetchType.EAGER, mappedBy="category", orphanRemoval = false)
@Column(nullable = true)
private List<SubCategory> subCategoryList = new ArrayList<>();

public Category(String categoryname) {
    this.name = categoryname;
}

和子类别

@Id //The unique id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;

@Column
private String name;

@JsonIgnore
@ManyToOne(cascade = {CascadeType.ALL}, fetch = FetchType.EAGER)
@JoinColumn(name="category_id")
Category category;

/**
 * @param name
 */
public SubCategory(String name) {
    super();
    this.name = name;
}

我还有一个文件数据。我的类路径中的sql。当我启动spring启动应用程序以插入默认值时，将加载此文件

--insert default category
INSERT INTO public.category(id, name)   VALUES (1, 'Webtoon');
INSERT INTO public.category(id, name)   VALUES (2, 'Ebook');
INSERT INTO public.category(id, name)   VALUES (3, 'Education');

--insert sub category
INSERT INTO public.sub_category(id, name, category_id)  VALUES (1, 'Action', 1);
INSERT INTO public.sub_category(id, name, category_id)  VALUES (2, 'Adventure', 1);
INSERT INTO public.sub_category(id, name, category_id)  VALUES (3, 'Thriller', 1);

一旦应用程序启动，当我调用我的服务创建另一个子类别时，我得到一个Id发布异常

    Optional<Category> categoryOpt =  categoryService.findById(Long.parseLong("1"));
    Assert.assertTrue("The category mus be present",categoryOpt.isPresent()); //The data with id 1 is found
    Assert.assertNotNull("The category must not be null. It should be loaded from ressources", categoryOpt.get().getId());

    //Spring generate id  instead of getting the correct sequence in database
    Category category = new Category("My-Category-Test");
    category = categoryService.create(category);

    Assert.assertNotNull("Category id must not be null", category.getId());

Spring使用已经存在的数据生成自己的序列，而不是从数据库中获取正确的序列。所以我得到了一个例外：

2020-01-29 01:00:02.848跟踪9148---[nio-9103-exec-1]o.h.类型。描述符。sql。BasicBinder:绑定参数[1]为[BIGINT]-[1]2020-01-29 01:00:02.849跟踪9148---[nio-9103-exec-1]o.h.type。描述符。sql。BasicBinder:绑定参数[2]为[VARCHAR]-[My Category Test]2020-01-29 01:00:02.860 WARN 9148---[nio-9103-exec-1]o.h.引擎。jdbc。spi。SqlExceptionHelper:SQL错误：0，SQLState:23505 2020-01-29 01:00:02.860错误9148---[nio-9103-exec-1]o.h.engine。jdbc。spi。SqlExceptionHelper:ERREUR:重复键的值会打破唯一约束«sub_category_pkey»

我如何告诉JPA找到正确的序列？

Answer 1

我找到了解决办法。当id被硬编码添加时，不会使用自动增量，这就是为什么hibernate仍然指向1，例如，即使1已经被手动插入。

所以我改变了我的脚本，像这样使用自动递增

--insert default category
INSERT INTO public.category(name)   VALUES ('Webtoon');
INSERT INTO public.category(name)   VALUES ('Ebook');
INSERT INTO public.category(name)   VALUES ('Education');

--insert sub category
INSERT INTO public.sub_category(name, category_id) SELECT 'Action', id FROM public.category where public.category.name = 'Webtoon';
INSERT INTO public.sub_category(name, category_id) SELECT 'Adventure', id FROM public.category where public.category.name = 'Webtoon';
INSERT INTO public.sub_category(name, category_id) SELECT 'Thriller', id FROM public.category where public.category.name = 'Webtoon';

这样，数据库和hibernate就可以使用自动增量