Question

我对java持久性很新。我的数据库模型有两个表：学生和联系人，每个学生可以有很多紧急联系人，但每个联系人只能属于一个学生。

在我的控制器中，帖子正文被正确地解析为包含联系人对象列表的学生对象。 但是，没有任何内容添加到“联系人”表中，并且学生表中没有添加任何内容，以暗示该学生可以引用联系人列表。可能有一个简单的解决方案，但经过几个小时的搜索，我找不到它。

Controller.java

@RestController
@RequestMapping("/students")
public class StudentController {

    @Autowired
    StudentRepository studentRepository;

    @RequestMapping(method = RequestMethod.POST)
    public void submitStudents(@RequestBody Map<Long,Student> students) {
        System.out.println("==========Updating database==========");
        students.values().forEach(student -> {
            System.out.println(student.getContacts().get(0).getParentTitle());
            studentRepository.save(student);});
    }
}

Student.java

@Entity(name="Student")
public class Student {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    private String firstName;
    private String lastNames;

    @OneToMany(targetEntity = Contact.class, mappedBy = "student", fetch = FetchType.EAGER)
    private List<Contact> contacts = new ArrayList<>();

    // Spring needs a no-args constructor
    public Student() {}

    public List<Contact> getContacts() {
        return contacts;
    }

    public void setContacts(List<Contact> contacts) {
        this.contacts = contacts;
    }

    public String getFirstName() {
        return firstName;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastNames() {
        return lastNames;
    }

    public void setLastNames(String lastNames) {
        this.lastNames = lastNames;
    }

    // not sure if I really need this, contacts were added to the student object before I had this method
    public void addContact(Contact contact) {
        System.out.println("adding contact");
        contact.setStudent(this);
        contacts.add(contact);
    }

    @Override
    public boolean equals(Object object) {
        if (!(object instanceof Student)) {
            return false;
        }

        return
            this.id == ((Student) object).getId();
    }
}

Contact.java

@Entity
public class Contact {

    @Id
    @GeneratedValue
    private Long id;

    @ManyToOne
    private Student student;

    private String phone;

    public Contact() {}

    public Student getStudent() {
        return student;
    }

    public void setStudent(Student student) {
        System.out.println("setting student to "+student);
        this.student = student;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public Long getId() { return id; }
}

Answer 1

你需要通过将CascadeType添加到@OneToMany来告诉Hibernate级联：

<?php
$file = file('/home/file.txt');
$selected_tag = implode(PHP_EOL,array_splice($file,5));
$result = implode(PHP_EOL,$file);
echo $result;
?>

JPA hibernate不将子实体存储在OneToMany关联中

1 个答案: