Spring Boot和MySQL获得一对多关系的请求

问题描述

我在MySQL，用户，机构和角色中有3个表

1. 用户与机构之间的一对多关系（一个用户可以在一个机构工作，而一个机构可以有很多用户）

数据库中的机构已经插入，用户只能在特定的现有机构中工作。

我将2条记录手动添加到我的数据库中，供用户和机构使用。

但是当我发送getAllUsers或getAllInstitutions请求时，会得到以下json主体，这是一个无限循环。

---------用户模型--------

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@ToString

@Entity
@Table(name = "user")
public class User {
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="user_Id")
    private int userId;
    @Column(name="name")
    private String name;
    @Column(name="lastname")
    private String lastname;
    @Column(name="email")
    private String email;
    @Column(name="password")
    private String password;
    @Column(name="isActive")
    private boolean isActive;
    @Column(name="lastActive")
    private String lastActive;
    @Column(name="createdDate")
    private String createdDate;
    @Column(name="isBlocked")
    private boolean isBlocked;
    
    @ManyToOne(fetch = FetchType.LAZY,optional = false)
    @JoinColumn(name = "institution_id",nullable = false)
    private Institution institution;
    
    @ManyToMany(fetch = FetchType.LAZY,cascade = CascadeType.PERSIST)
    @JoinTable(name = "user_has_role",joinColumns = {
                    @JoinColumn(name = "user_id",referencedColumnName = "user_id",nullable = false,updatable = true)},inverseJoinColumns = {
                    @JoinColumn(name = "role_id",referencedColumnName = "role_id",updatable = true)})
    private Set<Role> roles = new HashSet<>();

}

---------机构模型-----------

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@ToString

@Entity
@Table(name = "institution")
public class Institution {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="institution_Id")
    private int institutionId;
    @Column(name="name")
    private String name;
    @Column(name="type")
    private String type;
    @Column(name="location")
    private String location;
    @OneToMany(mappedBy = "institution",fetch = FetchType.LAZY)
    private Set<User> user;
    
}

---------角色模型----------

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@ToString

@Entity
@Table(name = "role")
public class Role {
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="role_Id")
    private int roleId;
    @Column(name="name")
    private String name;
    @Column(name="description")
    private String description;
    @ManyToMany(mappedBy = "roles",fetch = FetchType.LAZY)
    private Set<User> users = new HashSet<>();

}

--------控制器-----------

@GetMapping("/getAllUsers")
public List<User> getAllUsers() {
    return (List<User>) userrepository.findAll();
}

@PostMapping("/addUser")
public String addUser(@RequestBody User user) {
    userrepository.save(user);
    return "role saved with name: " + user.getName();
}

@GetMapping("/getAllInstitutions")
public List<Institution> getAllInstitutions() {
    return (List<Institution>) institutionrepository.findAll();
}

@PostMapping("/addInstitution")
public String addInstitution(@RequestBody Institution institution) {
    institutionrepository.save(institution);
    return "institution saved with name: " + institution.getName();
}

--------- getAllInstitutions的api请求主体循环错误---------------

[
{
    "institutionId": 1,"name": "Bank Byblos","type": "Bank","location": "sen el fil","user": [
        {
            "userId": 3,"name": "user1","lastname": "testtest","email": "[e-mail]","password": "user1123","lastActive": "11/11/21","createdDate": "06/05/20","institution": {
                "institutionId": 1,"user": [
                    {
                        "userId": 3,"institution": {
                            "institutionId": 1,"user": [
                                {
                                    "userId": 3,"institution": {
                                        "institutionId": 1,"user": [
                                            {
                                                "userId": 3,"institution": {
                                                    "institutionId": 1,"user": [
                                                        {
                                                            "userId": 3,"institution": {
                                                                "institutionId": 1,"user": [
                                                                    {
                                                                        "userId": 3,"institution": {
                                                                            "institutionId": 1,"user": [
                                                                                {

---------getAllÙsers的api请求主体循环错误---------------

[
{
    "userId": 3,"institution": {
        "institutionId": 1,"user": [
            {
                "userId": 3,"institution": {
                    "institutionId": 1,"user": [
                        {
                            "userId": 3,"institution": {
                                "institutionId": 1,"user": [
                                    {
                                        "userId": 3,"institution": {
                                            "institutionId": 1,"user": [
                                                {
                                                    "userId": 3,"institution": {
                                                        "institutionId": 1,"user": [
                                                            {
                                                                "userId": 3,"institution": {
                                                                    "institutionId": 1,"user": [

我有2个用户添加到我的数据库user1和user2中，并且还有2个添加到我的数据库user1的机构属于一个，而user2属于另一个（使用user表中的外键stitution_id） 请你能帮我解决这个问题吗？

解决方法

尝试如下修改您的代码：

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@ToString

@Entity
@Table(name = "institution")
public class Institution {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="institution_Id")
    private int institutionId;
    @Column(name="name")
    private String name;
    @Column(name="type")
    private String type;
    @Column(name="location")
    private String location;

    @OneToMany(mappedBy = "institution",fetch = FetchType.LAZY)
    @JsonIgnoreProperties(value = {"institution"})
    private Set<User> user;
    
}

使用@JsonIgnoreProperties批注忽略Institution模型中用户的属性指令。 现在它不会循环，因为在获取机构数据时您不会有任何想法。

也尝试在@JsonIgnoreProperties模型中添加User，这样可以解决您的问题。

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@ToString

@Entity
@Table(name = "user")
public class User {
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="user_Id")
    private int userId;
    @Column(name="name")
    private String name;
    @Column(name="lastname")
    private String lastname;
    @Column(name="email")
    private String email;
    @Column(name="password")
    private String password;
    @Column(name="isActive")
    private boolean isActive;
    @Column(name="lastActive")
    private String lastActive;
    @Column(name="createdDate")
    private String createdDate;
    @Column(name="isBlocked")
    private boolean isBlocked;
    
    @ManyToOne(fetch = FetchType.LAZY,optional = false)
    @JoinColumn(name = "institution_id",nullable = false)
    @JsonIgnoreProperties(value = {"user"})
    private Institution institution;
    
    @ManyToMany(fetch = FetchType.LAZY,cascade = CascadeType.PERSIST)