java - Spring Boot JPA向MySQL插入实体/对象时如何自动插入外键

Question

我尝试将包含外键的实体从 Spring boot JPA 插入到 MYSQL。但出现错误:

java.sql.SQLIntegrityConstraintViolationException: Column 'role_role_id' cannot be null.

当我将 null 插入到不允许 null 的列时，我知道这是一个错误。我知道解决方法(请参阅下面的 myMainController)是获取对象角色(外键)设置到我的用户对象中，然后将用户对象插入数据库(数据库中的新行)(角色的必要数据已经在数据库中)。但我希望当我插入用户时，它会自动插入对象角色，因为我已经清楚地设置了关系(更多信息请参阅我在用户实体和角色实体中的图片)。请参阅我的代码。

这是错误:

java.sql.SQLIntegrityConstraintViolationException: Column 'role_role_id' cannot be null.

这是我的MainRestController

@RestController
public class MyMainController {

@Autowired
private UserRepository service;

@RequestMapping("/i")
@ResponseBody
public String Welcome() {
    return "Welcome!";
}
@JsonIgnore
@RequestMapping(value = "/", //
        method = RequestMethod.GET, //
        produces = { MediaType.APPLICATION_JSON_VALUE })
@ResponseBody
public User initData() {




    User user = new User();
    user.setUserId(4);
    user.setPassword("1234");
    user.setFullname("Nguyễn Văn D");
    user.setPhonenumber("012345678");
    user.setAddress("2 đường Số 7 Bình Trị Dông");
    user.setFontIdCardImg("p2fontid.jpg");
    user.setBackIdCardImg("p2backid.jpg");
    user.setRoleId(2);
    user.setAreaId(2);

//      Role role = new Role();
//      role.setRoleId(user.getRoleId());   / My fix here
//      user.setRole(role);

    service.save(user);
    return user;
}

}

这是我的用户实体:

@Entity
@Table(name="user")
@NamedQuery(name="User.findAll", query="SELECT u FROM User u")
public class User implements Serializable {
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy=GenerationType.AUTO)
@Column(name="user_id", unique=true, nullable=false)
private Integer userId;

@Column(length=1000)
private String address;

@Column(name="area_id")
private Integer areaId;

@Column(name="back_id_card_img", length=200)
private String backIdCardImg;

@Column(name="font_id_card_img", length=200)
private String fontIdCardImg;

@Column(length=45)
private String fullname;

@Column(length=45)
private String password;

@Column(length=45)
private String phonenumber;

@Column(name="role_id")
private Integer roleId;

//bi-directional many-to-one association to Accident
@OneToMany(mappedBy="user")
private List<Accident> accidents;

//bi-directional many-to-one association to Area
@ManyToOne
@JoinColumn(name="area_area_id")
private Area area;

//bi-directional many-to-one association to Policeworktime
@ManyToOne
@JoinColumn(name="policeworktime_police_user_id")
private Policeworktime policeworktime;

//bi-directional many-to-one association to Role
@ManyToOne(cascade={CascadeType.ALL})
@JoinColumn(name="role_role_id", nullable=false)
private Role role;

public User() {
}

public Integer getUserId() {
    return this.userId;
}

public void setUserId(Integer userId) {
    this.userId = userId;
}

public String getAddress() {
    return this.address;
}

public void setAddress(String address) {
    this.address = address;
}

public Integer getAreaId() {
    return this.areaId;
}

public void setAreaId(Integer areaId) {
    this.areaId = areaId;
}

public String getBackIdCardImg() {
    return this.backIdCardImg;
}

public void setBackIdCardImg(String backIdCardImg) {
    this.backIdCardImg = backIdCardImg;
}

public String getFontIdCardImg() {
    return this.fontIdCardImg;
}

public void setFontIdCardImg(String fontIdCardImg) {
    this.fontIdCardImg = fontIdCardImg;
}

public String getFullname() {
    return this.fullname;
}

public void setFullname(String fullname) {
    this.fullname = fullname;
}

public String getPassword() {
    return this.password;
}

public void setPassword(String password) {
    this.password = password;
}

public String getPhonenumber() {
    return this.phonenumber;
}

public void setPhonenumber(String phonenumber) {
    this.phonenumber = phonenumber;
}

public Integer getRoleId() {
    return this.roleId;
}

public void setRoleId(Integer roleId) {
    this.roleId = roleId;
}

public List<Accident> getAccidents() {
    return this.accidents;
}

public void setAccidents(List<Accident> accidents) {
    this.accidents = accidents;
}

public Accident addAccident(Accident accident) {
    getAccidents().add(accident);
    accident.setUser(this);

    return accident;
}

public Accident removeAccident(Accident accident) {
    getAccidents().remove(accident);
    accident.setUser(null);

    return accident;
}

public Area getArea() {
    return this.area;
}

public void setArea(Area area) {
    this.area = area;
}

public Policeworktime getPoliceworktime() {
    return this.policeworktime;
}

public void setPoliceworktime(Policeworktime policeworktime) {
    this.policeworktime = policeworktime;
}

public Role getRole() {
    return this.role;
}

public void setRole(Role role) {
    this.role = role;
}

}

这是我的角色实体:

@Entity
@Table(name="role")
@NamedQuery(name="Role.findAll", query="SELECT r FROM Role r")
public class Role implements Serializable {
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy=GenerationType.AUTO)
@Column(name="role_id", unique=true, nullable=false)
private Integer roleId;

@Column(name="role_name", length=45)
private String roleName;

//bi-directional many-to-one association to User
@OneToMany(mappedBy="role", cascade={CascadeType.ALL})
private List<User> users;

public Role() {
}

public Integer getRoleId() {
    return this.roleId;
}

public void setRoleId(Integer roleId) {
    this.roleId = roleId;
}

public String getRoleName() {
    return this.roleName;
}

public void setRoleName(String roleName) {
    this.roleName = roleName;
}

public List<User> getUsers() {
    return this.users;
}

public void setUsers(List<User> users) {
    this.users = users;
}

public User addUser(User user) {
    getUsers().add(user);
    user.setRole(this);

    return user;
}

public User removeUser(User user) {
    getUsers().remove(user);
    user.setRole(null);

        return user;
    }

}

Answer 1

您不需要创建列roleId。您只需将关系与表放在一起即可。例如，在我的情况下，我有具有角色的 OneToMany 用户。我只在 MySql DB 中建立了关系。然后，您可以创建自己的实体或使用 JPA 工具。 User实体有一个Role对象，Role实体有一个List。

@Entity
@Table(name="role")
@NamedQuery(name="Role.findAll", query="SELECT r FROM Role r")
public class Role implements Serializable {
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy=GenerationType.AUTO)
@Column(name="role_id", unique=true, nullable=false)
private Integer roleId;

@Column(name="role_name", length=45)
private String roleName;

//bi-directional many-to-one association to User
@OneToMany(mappedBy="role")
private List<User> users;

public Role() {
}

public Integer getRoleId() {
    return this.roleId;
}

public void setRoleId(Integer roleId) {
    this.roleId = roleId;
}

public String getRoleName() {
    return this.roleName;
}

public void setRoleName(String roleName) {
    this.roleName = roleName;
}

public List<User> getUsers() {
    return this.users;
}

public void setUsers(List<User> users) {
    this.users = users;
}

public User addUser(User user) {
    getUsers().add(user);
    user.setRole(this);

    return user;
}

public User removeUser(User user) {
    getUsers().remove(user);
    user.setRole(null);

    return user;
}

 }


@Entity
@Table(name = "user")
@NamedQuery(name = "User.findAll", query = "SELECT u FROM User u")
public class User implements Serializable {
private static final long serialVersionUID = 1L;


// bi-directional many-to-one association to Role
@ManyToOne
@JoinColumn(name = "role_role_id", nullable = false)
private Role role;



public Role getRole() {
    return this.role;
}

public void setRole(Role role) {
    this.role = role;
}



}