即使使用级联 = CascadeType.ALL POST/PUT/DELETE 方法时也会出现限制休眠异常

Question

I'm trying to add a new Object to the h2-memory data base with POST Rest API. I got this error : nested exception is org.hibernate.exception.ConstraintViolationException

In my Expense Entity I had put @ManyToOne(cascade=CascadeType.ALL) so it's not supposed to create the category object before creating the expense object , isn't?

Thanks in advance. Here is my entites: public class Expense {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id", updatable = false, nullable = false)
private Long id;
private String description;
@Column(name = "expense_date")
private Instant expenseDate;
@Column(name = "location")
private String location;
@ManyToOne(cascade={CascadeType.ALL})
@Nullable
@JoinColumn(name = "category_id", referencedColumnName = "id", nullable = false)
private Category category;
@ManyToOne(cascade=CascadeType.ALL)
@JoinColumn(name = "user_id", referencedColumnName = "id", nullable = false)
@Nullable
@JsonIgnore
private User user;}

Category Class public class Category {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id", updatable = false, nullable = false)
private Long id;
@NonNull
private String name;}

User Class: public class User {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id", updatable = false, nullable = false)
private Long id;
private String name;
private String email;}

Answer 1

Problem solved when I removed nullable=false from @JoinColumn. because in Post method , I did not provide the id because it's generated so it's theorically nullable

Answer 2

You have an error in your definition of Expense class. The annotation @Nullable - allows NULL values, and nullable = false - don`t allow.