hibernate - 无法删除或更新父行 : a foreign key constraint fails with Join tables

Question

我正在使用 Java 8 和 Hibernate5/JPA2。

当我尝试删除 Job 对象时出现以下错误:

com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Cannot delete or update a parent row: a foreign key constraint fails (www.subcategory, CONSTRAINT FK_SUBCATEGORY_CATEGORY FOREIGN KEY (CATEGORY_ID) REFERENCES category (ID) ON DELETE NO ACTION ON UPDATE NO ACTION)

表格

+============+   +=================+   +================+
| job        |   |  job_category   |   |  category      |
+============+   +=================+   +================+
| ID         |   |  JOB_ID         |   |  ID            |
|            |   |  CAT_ID         |   |                |
+============+   +=================+   +================+

                 +==================+   +=================+
                 | job_subcategory  |   | subcategory     |   
                 +==================+   +=================+
                 |  JOB_ID          |   |  ID             |
                 |  SUBCAT_ID       |   |  CATEGORY_ID    |
                 +==================+   +=================+

一个Job可以有很多Categories。一个 Category 可以有很多 SubCategories。

Job.java

@ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
@JoinTable(name = "job_category", joinColumns = {
        @JoinColumn(name = "JOB_ID", referencedColumnName = "ID") }, inverseJoinColumns = {
                @JoinColumn(name = "CAT_ID", referencedColumnName = "ID") })
private Set<Category> categories;

@ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
@JoinTable(name = "job_subcategory", joinColumns = {
        @JoinColumn(name = "JOB_ID", referencedColumnName = "ID") }, inverseJoinColumns = {
                @JoinColumn(name = "SUBCAT_ID", referencedColumnName = "ID") })
private Set<SubCategory> subCategories;

类别.java

@JsonIgnore
@OneToMany(cascade = CascadeType.ALL, fetch=FetchType.EAGER, mappedBy = "category")
private Set<SubCategory> subCategories;

子类别.java

@ManyToOne(fetch=FetchType.EAGER)
@JoinColumn(name = "CATEGORY_ID")
private Category category;

JpaDao.java

protected void remove(Job entity) {
    entityManager.remove(entity);
}

当我删除 Job 对象时，我希望它从 job 表和连接表(job_category 和job_subcategory)，但不是 category 和 subcategory 表。

感谢任何建议。

更新

我尝试删除 subcategories 和 categories 然后是 job:

public boolean delete(Job job) {
    Set<SubCategory> subCategories = job.getSubCategories();
    if (subCategories != null) {
        for (SubCategory subCategory : subCategories) {
            entityManager.remove(subCategory);
        }
    }
    Set<Category> categories = job.getCategories();
    if (categories != null) {
        for (Category category : categories) {
            entityManager.remove(category);
        }
    }
    entityManager.remove(job);
    return true;
}

但我仍然得到同样的错误:

Cannot delete or update a parent row: a foreign key constraint fails (www.job_subcategory, CONSTRAINT fk_job_sub_subcategory FOREIGN KEY (SUBCAT_ID) REFERENCES subcategory (ID) ON DELETE NO ACTION ON UPDATE NO ACTION)

该错误仅在我完成事务 (@Transactional) 时发生，所以它看起来像是在 Hibernate 执行提交时发生的。

更新

我尝试以下操作:

public boolean delete(Job job) {
    job.setSubCategories(null);
    job.setCategories(null);
    super.remove(job);
    return true;
}

但再次得到以下内容:

Cannot delete or update a parent row: a foreign key constraint fails (www.person_job, CONSTRAINT fk_person_job_person FOREIGN KEY (PER_ID) REFERENCES person (ID) ON DELETE NO ACTION ON UPDATE NO ACTION)

更新

我尝试:

public boolean delete(Job job) {
    job.setSubCategories(null); 
    job.setCategories(null);
    job.setPerson(null);        
    super.remove(job);
    return true;
}

并得到:

IllegalArgumentException: Source must not be null

Answer 1

好吧，试试这样的东西

public boolean delete(Job job) {
    Set<SubCategory> subCategories = job.getSubCategories();
    if (subCategories != null) {
        job.getSubCategories().clear();
        for (SubCategory subCategory : subCategories) {
            subCategory.setJob(null);
            entityManager.remove(subCategory);
        }
    }
    Set<Category> categories = job.getCategories();
    if (categories != null) {
        job.getCategories().clear();
        for (Category category : categories) {
            category.setJob(null);
            entityManager.remove(category);
        }
    }
    job.setPerson(null);
    //if necessary:
    //Person.setJob(null);        
    entityManager.remove(job);
    return true;
}

此外，为什么您有 super.remove(job) 而不是我刚刚发布的代码中的 entityManager.remove(job)？

这段代码是否仍然出现异常？