@jsonignore在春季mvc没有按预期工作

Question

usercontroller.java

@RequestMapping("/listusersjson")
    public ResponseEntity<Iterable<User>> getListofUsersJson() {
        Iterable<User>   users = userService.listUser(); 
        return new ResponseEntity<>(users, HttpStatus.OK);

    }

user.java

@Entity
public class User {

    @Id
    @GeneratedValue
    @Column(name="user_id")
    private Integer id;

    private String name;

    private String email;

    private String password;

    private int enabled;

    public User(Integer id) {
        super();
        this.id = id;
    }


    public User() {
        super();
    }

    @ManyToMany(cascade = CascadeType.ALL)
    @JoinTable(name = "user_role", joinColumns = { @JoinColumn(name = "user_id") }, inverseJoinColumns = {
            @JoinColumn(name = "role_id") })
    @JsonIgnore
    private List<Role> roless;

    @OneToMany(mappedBy = "user", cascade = CascadeType.ALL)
    @JsonIgnore
    private List<Cart> carts ;


    @OneToMany(mappedBy = "user", cascade = CascadeType.ALL)
    @JsonIgnore
    private List<OrderDetails> orderDetails ;

}

例外

 HTTP Status 500 - Could not write JSON: failed to lazily initialize a collection of role: com.addtocart.dto.User.roless, could not initialize proxy - no Session (through reference chain: java.util.ArrayList[0]->com.addtocart.dto.User["roles"]); nested exception is org.codehaus.jackson.map.JsonMappingException: failed to lazily initialize a collection of role: com.addtocart.dto.User.roless, could not initialize proxy - no Session (through reference chain: java.util.ArrayList[0]->com.addtocart.dto.User["roles"])

即使我已经添加了@jsonignore所有必需的字段,其中存在关联性和lazyinitialization异常的可能性,但我仍然得到上述异常.我不知道我缺少什么.

Answer 1

尝试@JsonIgnore使用getter而不是字段,例如

@JsonIgnore
public List<Cart> getCarts() {...}