Why can’t I insert an entity twice by using Spring Data Jdbc？

Question

my entity:

@Table("user")
public class User {

    @Id
    private Long user_id;
    private String username;
    private String password;

    public User(String username, String password) {
        this.username = username;
        this.password = password;
    }

    public User() {
    }

    public Long getUser_id() {
        return user_id;
    }

    public void setUser_id(Long user_id) {
        this.user_id = user_id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

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

my repository:

public interface UserRepository extends CrudRepository<User, Long> {

    @Query("select * from user where username = :username")
    User findByUsername(@Param("username") String username);
}

my sql for creating the user table:

CREATE TABLE `user` (
  `user_id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `username` varchar(32) NOT NULL,
  `password` text NOT NULL,
  PRIMARY KEY (`user_id`),
  UNIQUE KEY `UINQUE_USERNAME`(`username`) USING BTREE
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

User userForRegister = new User(username, passwordEncoder.encode(password));
userRepository.save(userForRegister)

If I execute the line of 'userRepository.save(userForRegister)', I will insert an entity successfully the first time.

But, if I want to insert another user entity with different username, i will get an error:

2021-01-08 21:37:38.242  INFO 11180 --- [nio-8080-exec-8] c.k.centre.controller.UserController     : Failed to execute DbAction.InsertRoot(entity=com.***.***.Entity.User@65bc9ea1, generatedId=null)

I can insert it until I delete all the data of user table. Is there any point I missed?

Do they have different user names? What is the stack trace you are getting? — Jens Schauder, Jan 08 '21 at 13:57
Side note: I recommend sticking to the java conventions for names which includes: No underscore for properties and fields. — Jens Schauder, Jan 08 '21 at 13:58
yeah！they have different names.It seems that I solved it~ Just add a annotation of @Column("userId") — ge1mina023, Jan 08 '21 at 15:23

zawarudo · Accepted Answer · 2021-01-14T14:32:08.650

1

I think that GenerateValue would solve the problem

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "user_id")
private Long user_id;

Also I think you should map your ther fields to database columns using @Column annotation

@Column(name = "user_id")
private Long user_id;
@Column(name = "username")
private String username;
@Column(name = "password")
private String password;

edited Jan 14 '21 at 14:32

answered Jan 08 '21 at 14:02

zawarudo

1,907
2
10
20

1

It seems that spring jdbc doesn't have the annotation of @GeneratedValue. – ge1mina023 Jan 08 '21 at 14:12
http://zetcode.com/springboot/crudrepository/ it is part of javax.persistence package – zawarudo Jan 08 '21 at 14:18
What dependence should I add？ – ge1mina023 Jan 08 '21 at 14:52
https://mvnrepository.com/artifact/javax.persistence/javax.persistence-api/2.2 – zawarudo Jan 08 '21 at 15:00
It seems that I solved it~ Just add a annotation of @Column("userId").I am so confused that why can I insert one in the first time. – ge1mina023 Jan 08 '21 at 15:21
@ge1mina023 if you solved it by adding an `@Column("userId")` you should make that an answer and accept it. The answer here is most is not the correct answer since `javax.persistence` annotations have no effect on Spring Data JDBC at all. – Jens Schauder Jan 14 '21 at 08:35
Have you noticed the other part of my answer where I state that he should use @Column annotation? – zawarudo Jan 14 '21 at 13:46

score 0 · Answer 2 · answered Jan 08 '21 at 14:02

0

Try adding @GeneratedValue(strategy = GenerationType.IDENTITY) to your user_id. This tells Hibernate that id is generated by your database. You configured your database primary key as autoincrement Column. Take also a look here.

answered Jan 08 '21 at 14:02

Tr1monster

328
3
13

It seems that spring jdbc doesn't have the annotation of @GeneratedValue. – ge1mina023 Jan 08 '21 at 14:13
It should be part of the spring data package. I think you should look why you can’t use the annotation. Take your favourite dependency analyser (IntelliJ maven helper is great) and look at the dependency tree for the Java persistence api. It should be somewhere under spring data. – Tr1monster Jan 08 '21 at 15:57
It seems that I solved it~ Just add a annotation of @Column("userId").I am so confused that why can I insert one in the first time. – ge1mina023 Jan 08 '21 at 16:08
I'm also a bit confused. This should not be possible. maybe you set your id manually at some point. Without an exmaple is further investigation difficult. – Tr1monster Jan 11 '21 at 08:24
1

This annotation is not part of Spring Data JDBC, you are confusing it with Spring Data JPA or actually JPA. – Jens Schauder Jan 14 '21 at 08:36

Why can’t I insert an entity twice by using Spring Data Jdbc？

2 Answers2