Hibernate使用@OneToMany和@ManyToOne上傳資料，但外鍵仍然為空

模塊代碼：

@Data
@NoArgsConstructor
@ToString
@Entity(name = "modules")
@Table(name = "modules")
public class Module {

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

    @Column(name = "module_name")
    private String moduleName;

    @Column(name = "module_code")
    private String moduleCode;

    @Column(name = "moderator_lecturer")
    private String moderatorLecturerId;

    @Column(name = "secondary_lecturer")
    private String secondaryLecturerId;

    @OneToMany(mappedBy = "foreignModuleId", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    private List<Assessment> assessments;

    public void addAssessment(Assessment assessment) {
        assessments.add(assessment);
    }
}

分配代碼

@Data
@NoArgsConstructor
@ToString
@Entity(name = "assessments")
@Table(name = "assessments")
public class Assessment {

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

    @Enumerated(EnumType.STRING)
    @Column(name = "assessment_type")
    private AssessmentType assessmentType;

    @Column(name = "assessment_weight")
    private int assessmentWeight;

    @Column(name = "assessment_weeks")
    private String weeks;

    @Column(name = "assessment_upload_date")
    private LocalDate uploadDate;

    @Column(name = "assessment_deadline_date")
    private LocalDate deadlineDate;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "assessment_belongsTo_module", referencedColumnName = "module_id")
    private Module foreignModuleId;
}

一個模塊可以有許多評估，因此我選擇了這些注釋。我首先從一個 excel 檔案中提取這些資料并將它們組合在一個串列中（稍后作為一個名為“模塊”的引數傳遞）。該串列的格式為： Module(moduleId=0, moduleName=Programming Principles and Algorithms , moduleCode= CCS1110, moderatorLecturerId=Dr Stamatopoulou, secondaryLecturerId= Dr Efremidis, Assessments=[Assessment(assessmentId=0, AssessmentType=ASSESSED_5LAB, AssessmentWeight=3 , 周=00001000000000000, uploadDate=null,deadlineDate=null,foreignModuleId=null),Assessment(assessmentId=0,assessmentType=ASSESSED_LAB, AssessmentWeight=65,weeks=0000000000000001,uploadDate=null,deadlineDate=null,externalModuleId=null)模塊(moduleId=0, moduleName=Programming Methodology and Design, moduleCode= CCS1115,

Then I upload the list on the database:

@NoArgsConstructor
@Data
public class AppDAOImpl implements AppDAO{

    private SessionFactory factory;

    public void upload(List<com.project.model.Module> modules) {
        Session currentSession = factory.getCurrentSession();
        try {
            currentSession.beginTransaction();
            for(Module module : modules) { 
                currentSession.save(module);
            }
            currentSession.getTransaction().commit();
        }
        finally {
            currentSession.close();
            factory.close();
        }
    
    }
}

When I execute Hibernate create queries of form: Hibernate: insert into modules (moderator_lecturer, module_code, module_name, secondary_lecturer) values (?, ?, ?, ?) Hibernate: insert into assessments (assessment_type, assessment_weight, assessment_deadline_date, assessment_belongsTo_module, assessment_upload_date, assessment_weeks) values (?, ?, ?, ?, ?, ?) Hibernate: insert into assessments (assessment_type, assessment_weight, assessment_deadline_date, assessment_belongsTo_module, assessment_upload_date, assessment_weeks) values (?, ?, ?, ?, ?, ?)

But in the database on the table for Assessments, the field assessment_belongsTo_module is null.

My database has this form:

我已經嘗試了很多東西，但無法解決問題。我也讀過類似的執行緒，但仍然沒有。也許我在資料庫中的每個表上創建欄位的方式有問題（例如外鍵）？

uj5u.com熱心網友回復：

1. 不要將名稱 Module 用于類，例如 MModule。它與 java.lang.Module 混淆。
2. 創建 JpaRepository MModuleRepository。然后在控制器中，簡單地寫一些類似的東西

    for(MModule module :modules){
       moduleRepository.save(module);
    }

uj5u.com熱心網友回復：

導致這種情況的問題與我沒有在評估類中初始化屬性“foreignModuleId”有關。所以當我在某個時候從我的 excel 中提取資料時，我有以下幾行：

assessment.setForeignModuleId(module); // I add the module in which the assessment belongs.
module.addAssessment(assessment); // I then add that assessment to the @OneToMany assessments List

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