java.sql.SQLException：字段“participant_one_fk_id”没有默认值

Question

I am having a problem creating a match with two members. I cannot save participants to the match. Perhaps the problem is that do i use two one-to-one anatations in my project?

 @Entity
    @Table(name = "mach")
    public class TournamentMatch {
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "mach_id")
    private int id;

    private LocalDate startTime;

    private LocalDate finischTime;

    private BigDecimal scores;

    @ManyToOne
    @JoinColumn(name = "tournament_fk_id")
    private Tournament tournament;

    @OneToOne(optional = false, cascade = {CascadeType.PERSIST, CascadeType.REMOVE, CascadeType.MERGE})
    @JoinColumn(name = "participant_two_fk_id")
    private Participant participantTwo;

    @OneToOne(optional = false, cascade = {CascadeType.PERSIST, CascadeType.REMOVE, CascadeType.MERGE})
    @JoinColumn(name = "participant_one_fk_id")
    private Participant participantOne;

    public TournamentMatch() {
    }

class participant match

@Entity
public class Participant {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "participant_id")
    private int id;

    @NotNull
    @Column(name = "nick_name")
    private String nickName;

    public Participant() {
    }
...gets,sets

i am trying to save to the repository

  @Override
    public void save(TournamentMatch match) {
        tournamentMatchRepository.save(match);
    }

this is my JSON request

 {
    "id": 0,
    "startTime": "2018-10-10",
    "finischTime": "2018-10-11",
    "scores": "3",
  
    
   "tournament":{
   "id": 0,
   "name": "ChempionsLigue1"
 },
      "participantOne":{
   "id": 0,
   "nickName": "PlayerOne"
  
 },
  "participantTwo":{
   "id": 0,
   "nickName": "PlayerTwo"
  
 }
 }

writes an error

java.sql.SQLException: Field 'participant_one_fk_id' doesn't have a default value

AUTO_INCREMENT PRIMARY KEY available in all classes

Answer 1

It seems that your column participant_one_fk_id does not have a default value. Try something like this

1. Add a default value to the column participant_one_fk_id Using -

   ALTER TABLE 'xxx' ALTER 'participant_one_fk_id' SET DEFAULT NULL

( I think the only first step will do the trick, try right after first step )

2. Supply some value to the participant_one_fk_id' column during insertion.

3. Add an auto increment to the column and add a primary key to it using the code :-

   ALTER TABLE 'xxx' CHANGE 'participant_one_fk_id' 'participant_one_fk_id' INT(10)AUTO_INCREMENT PRIMARY KEY;

If it complains about something regarding integer I know that "width" or whatever is deprecated so (10) might won't be required, but try with it first.