錯誤：更新或洗掉表“courses”違反表“teacher_courses”上的外鍵約束“fk998yb1badftsiklfh13bcw3ol”

我有兩個物體，在五個物體的模型中，當我運行我的代碼時沒有錯誤。但是，每當我從 insomnia 發出洗掉所有請求時，都會收到錯誤訊息：org.postgresql.util.PSQLException: ERROR: update or delete on table “courses”違反了表“teacher_courses”上的外鍵約束“fk998yb1badftsiklfh13bcw3ol”詳細資訊：鍵（ id)=(1) 仍然從表“teacher_courses”中參考。

我知道這兩個專案之間的級聯有問題，但我不知道如何解決這些問題。

package com.example.springapiwithsecuritydevelopment.model;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import lombok.Getter;
import lombok.Setter;

import javax.persistence.*;
import java.time.LocalDate;
import java.util.List;

@Entity
@Table(name = "courses")
@Getter @Setter
public class Course {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column
    private Integer id;

    @Column(unique = true)
    private String courseName;

    @Column
    private LocalDate courseStartDate;

    @Column
    private LocalDate courseEndDate;

    // One course to many lessons
    @OneToMany(mappedBy = "course", cascade = CascadeType.ALL, orphanRemoval = true)
    @JsonIgnoreProperties("course")
    private List<Lesson> lessonList;

    // Many courses to many Students
    @ManyToMany(mappedBy = "courseList", fetch = FetchType.LAZY, cascade = {CascadeType.DETACH, CascadeType.MERGE, CascadeType.REFRESH, CascadeType.REMOVE})
    @JsonIgnoreProperties("courseList")
    private List<Student> studentList;

    // Subject to course
    @ManyToOne()
    @JoinColumn(name = "subject_id")
    @JsonIgnoreProperties("courseList")
    private Subject subject;

    // ManyCourses to Many Teachers
    @ManyToMany(fetch = FetchType.LAZY, mappedBy = "courseList", cascade = {CascadeType.MERGE, CascadeType.DETACH, CascadeType.REFRESH})
    @JsonIgnoreProperties("courseList")
    private List<Teacher> teacherList;

    // Adding constructors
    public Course() {
    }

    public Course(String courseName, LocalDate courseStartDate, LocalDate courseEndDate) {
        this.courseName = courseName;
        this.courseStartDate = courseStartDate;
        this.courseEndDate = courseEndDate;
    }


}

package com.example.springapiwithsecuritydevelopment.model;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import lombok.Getter;
import lombok.Setter;

import javax.persistence.*;
import javax.validation.constraints.NotNull;
import java.time.LocalDate;
import java.util.List;

@Entity
@Getter @Setter
public class Teacher {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;

    @Column
    private String firstName;

    @Column
    private String secondName;

    @Column(nullable = false) @NotNull
    private LocalDate birthday;

    @Column
    private Integer age;

    @ManyToMany(cascade = {CascadeType.MERGE, CascadeType.DETACH, CascadeType.REFRESH}, fetch = FetchType.LAZY)
    @JoinTable(
            name = "teacher_courses",
            joinColumns = @JoinColumn(name = "teacher_id"),
            inverseJoinColumns = @JoinColumn(name = "course_id")
    )
    @JsonIgnoreProperties("teacherList")
    private List<Course> courseList;


    // Adding constructors
    public Teacher() {
    }

    public Teacher(String firstName, String secondName, LocalDate birthday, Integer age) {
        this.firstName = firstName;
        this.secondName = secondName;
        this.birthday = birthday;
        this.age = age;
    }
}

uj5u.com熱心網友回復：

你可以嘗試將教師類的級聯型別更改為

@ManyToMany(cascade = {CascadeType.MERGE, CascadeType.PERSIST,CascadeType.REFRESH})

uj5u.com熱心網友回復：

我的朋友找到了一個解決方案，如何在 JPA 中洗掉具有 ManyToMany 關系的物體（以及相應的連接表行）？.

最后，我只是把

  @PreRemove
    private void removeCoursesFromTeacher() {
        for (Teacher t : teacherList) {
            t.getCourseList().remove(this);
        }
    }

在關系的非擁有方。

標籤：爪哇 春天 弹簧靴 休眠 jpa

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