Spring JPA JoinTable

Question

I have three entities. I want to save a survey. The survey will contain all the data that is neccessary:id,section, questions. The survey_section_question table is created successfully and when I want to retrieve existing data I receive the desired object. I have a problem when I want to save a survey that has sections and questions.I receive the following error:

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

Does anyone see what is the error there? I attach the code for the three entities.Thanks in advance for the help!

    @Entity
    @Table(name="Surveys")
    @Data
    public class Survey {
        @Id
        @Column(name = "id")
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private Long id;
        private String name;
        private String description;
        private String createdBy;
    
        @ManyToMany(fetch = FetchType.EAGER, cascade = { CascadeType.PERSIST, CascadeType.MERGE })
        @JoinTable(
                name = "survey_section_question",
                joinColumns = @JoinColumn(name = "survey_id"),
                inverseJoinColumns = @JoinColumn(name = "section_id")
        )
        private List<SurveySection> sections;
    }

    @Entity
    @Table(name="SurveySections")
    @Data
    public class SurveySection {
        @Id
        @Column(name = "id")
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private Long id;
        private String name;
        private String description;
    
        @ManyToMany
        @JoinTable(
                name = "survey_section_question",
                joinColumns = @JoinColumn(name = "section_id"),
                inverseJoinColumns = @JoinColumn(name = "question_id")
        )
        private List<SurveyQuestion> questions;
    }

@Entity
@Table(name="SurveyQuestions")
@Data
public class SurveyQuestion {
    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private String description;
    private String createdBy;
    private boolean textAnswer;
    private boolean gradeAnswer;
}

The sended json:

{"id":1,"name":"mu","description":"sss","createdBy":"xx","sections":[{"id":5,"name":"s2","description":"","questions":[{"id":15,"name":"adawd","description":"awdawd","createdBy":"","textAnswer":true,"gradeAnswer":true}],"selectedQuestion":"15"}]}

The code used for update:

@PutMapping("/{id}")
Survey update(@RequestBody Survey surveyData, @PathVariable Long id) {
    return surveyService.findById(id)
            .map(survey -> {
                survey.setName(surveyData.getName());
              survey.setDescription(surveyData.getDescription());
                survey.setSections(surveyData.getSections());
                survey.setCreatedBy("Test");
                return surveyService.save(survey);
            })
            .orElseGet(() -> surveyService.save(surveyData));
}

The save for the survey service it is just a default call to jpa repository which calls save.

Answer 1

The fetch type is only used for queries. Your save repository method will simply call EntityManager.persist() or EntityManager.merge(). Merge will only merge the survey entity, not the children. You will need to manage the children manually in your surveyService.save() method.