Spring Boot-java.sql.SQLIntegrityConstraintViolationException:无法添加或更新子行：外键约束失败

我得到这个错误，我不能解决这个问题

基于这个话题有很多答案，但都不适合我

目标是保存

Todo

，然后保存

TaskTodo

（

Task

和

Todo

的连接表）

我试图保存并刷新

Todo

，然后保存

TaskTodo

，但失败了

有人能告诉我哪里出了问题吗

错误：

@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public abstract class Assignment {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;
    private String name;

}

@Entity
public class Todo extends Assignment {

    private boolean isChecked;

    @OneToMany(mappedBy = "todo")
    Set<TaskTodo> taskTodoSet;
}

@Entity
public class Task extends Assignment {

    private String description;

    @OneToMany(mappedBy = "task")
    public
    Set<TaskTodo> taskTodoSet;

    public Task() {}

    public Task(String name) {
        this.setName(name);
    }
}

@Entity
public class TaskTodo {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    Long id;

    @ManyToOne
    @JoinColumn(name = "task_id")
    Task task;

    @ManyToOne
    @JoinColumn(name = "todo_id")
    Todo todo;

    public TaskTodo(Task task, Todo todo) {
        this.task = task;
        this.todo = todo;
    }
}

@Override
public void saveTodo(Todo todo, Long taskId) {
    Task task = getTaskById(taskId);
    todoRepository.saveAndFlush(todo);
    TaskTodo taskTodo = new TaskTodo(task, todo);
    taskTodoRepository.save(taskTodo);
}

java.sql.SQLIntegrityConstraintViolationException:无法添加或更新子行：外键约束失败（

todo

task\u todo

，约束

FK8dn0kderp1dame65xsokdaavj

外键（

todo\u id

）引用

todo

（

id

）

赋值-父抽象类：

@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public abstract class Assignment {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;
    private String name;

}

@Entity
public class Todo extends Assignment {

    private boolean isChecked;

    @OneToMany(mappedBy = "todo")
    Set<TaskTodo> taskTodoSet;
}

@Entity
public class Task extends Assignment {

    private String description;

    @OneToMany(mappedBy = "task")
    public
    Set<TaskTodo> taskTodoSet;

    public Task() {}

    public Task(String name) {
        this.setName(name);
    }
}

@Entity
public class TaskTodo {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    Long id;

    @ManyToOne
    @JoinColumn(name = "task_id")
    Task task;

    @ManyToOne
    @JoinColumn(name = "todo_id")
    Todo todo;

    public TaskTodo(Task task, Todo todo) {
        this.task = task;
        this.todo = todo;
    }
}

@Override
public void saveTodo(Todo todo, Long taskId) {
    Task task = getTaskById(taskId);
    todoRepository.saveAndFlush(todo);
    TaskTodo taskTodo = new TaskTodo(task, todo);
    taskTodoRepository.save(taskTodo);
}

待办事项-域类：

@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public abstract class Assignment {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;
    private String name;

}

@Entity
public class Todo extends Assignment {

    private boolean isChecked;

    @OneToMany(mappedBy = "todo")
    Set<TaskTodo> taskTodoSet;
}

@Entity
public class Task extends Assignment {

    private String description;

    @OneToMany(mappedBy = "task")
    public
    Set<TaskTodo> taskTodoSet;

    public Task() {}

    public Task(String name) {
        this.setName(name);
    }
}

@Entity
public class TaskTodo {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    Long id;

    @ManyToOne
    @JoinColumn(name = "task_id")
    Task task;

    @ManyToOne
    @JoinColumn(name = "todo_id")
    Todo todo;

    public TaskTodo(Task task, Todo todo) {
        this.task = task;
        this.todo = todo;
    }
}

@Override
public void saveTodo(Todo todo, Long taskId) {
    Task task = getTaskById(taskId);
    todoRepository.saveAndFlush(todo);
    TaskTodo taskTodo = new TaskTodo(task, todo);
    taskTodoRepository.save(taskTodo);
}

保存待办事项和任务待办事项的服务功能：

@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public abstract class Assignment {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;
    private String name;

}

@Entity
public class Todo extends Assignment {

    private boolean isChecked;

    @OneToMany(mappedBy = "todo")
    Set<TaskTodo> taskTodoSet;
}

@Entity
public class Task extends Assignment {

    private String description;

    @OneToMany(mappedBy = "task")
    public
    Set<TaskTodo> taskTodoSet;

    public Task() {}

    public Task(String name) {
        this.setName(name);
    }
}

@Entity
public class TaskTodo {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    Long id;

    @ManyToOne
    @JoinColumn(name = "task_id")
    Task task;

    @ManyToOne
    @JoinColumn(name = "todo_id")
    Todo todo;

    public TaskTodo(Task task, Todo todo) {
        this.task = task;
        this.todo = todo;
    }
}

@Override
public void saveTodo(Todo todo, Long taskId) {
    Task task = getTaskById(taskId);
    todoRepository.saveAndFlush(todo);
    TaskTodo taskTodo = new TaskTodo(task, todo);
    taskTodoRepository.save(taskTodo);
}

---

我设法找出了问题所在

服务功能应如下所示：

@Override
public void saveTodo(Todo todo, Long taskId) {
    Task task = getTaskById(taskId);
    todo = todoRepository.saveAndFlush(todo); // This line is changed
    TaskTodo taskTodo = new TaskTodo(task, todo);
    taskTodoRepository.save(taskTodo);
}

原因是作为参数发送的

Todo

本身没有id，因此出现了错误

---

当我放置

todo=todoRepository.saveAndFlush（todo）时

，

saveAndFlush

返回的对象本身具有id。因为

TaskTodo

可以保存。

我设法找出了问题所在

服务功能应如下所示：

@Override
public void saveTodo(Todo todo, Long taskId) {
    Task task = getTaskById(taskId);
    todo = todoRepository.saveAndFlush(todo); // This line is changed
    TaskTodo taskTodo = new TaskTodo(task, todo);
    taskTodoRepository.save(taskTodo);
}

原因是作为参数发送的

Todo

本身没有id，因此出现了错误

---

当我放置

todo=todoRepository.saveAndFlush（todo）时

，

saveAndFlush

返回的对象本身具有id。因此可以保存

TaskTodo

。

Todo

在此处创建：

todoRepository.saveAndFlush（Todo）
Todo
在此处创建：
todoRepository.saveAndFlush（Todo）如果这与saveAndFlush有关，服务函数是否应该具有@Transactional注释？如果不使用saveAndFlush，这可能会对您的案例有所帮助？是的，它也有效。我发现即使没有
@Transactional
它也能工作。关键是放置
todo=todoRepository.save（todo）
如果这与saveAndFlush有关，服务函数是否应该有@Transactional注释？如果不使用saveAndFlush，这可能会对您的案例有所帮助？是的，它也有效。我发现即使没有
@Transactional
它也能工作。关键是放置
todo=todoRepository.save（todo）