JPA CascadeType.PERSIST

 

/*******************************************************************************
 * Copyright (c) 2005, 2014 springside.github.io
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 *******************************************************************************/
package com.lxz.entity;

import javax.persistence.*;

import org.apache.commons.lang3.builder.ToStringBuilder;
import org.hibernate.validator.constraints.NotBlank;

//JPA标识
@Entity
@Table(name = "t_task")
public class Task extends IdEntity {

	private String title;
	private String description;
	private User user;

	// JSR303 BeanValidator的校验规则
	@NotBlank
	public String getTitle() {
		return title;
	}

	public void setTitle(String title) {
		this.title = title;
	}

	public String getDescription() {
		return description;
	}

	public void setDescription(String description) {
		this.description = description;
	}

	// JPA 基于USER_ID列的多对一关系定义
	@ManyToOne(cascade = CascadeType.MERGE)
	@JoinColumn(name = "user_id")
	public User getUser() {
		return user;
	}

	public void setUser(User user) {
		this.user = user;
	}

	@Override
	public String toString() {
		return ToStringBuilder.reflectionToString(this);
	}
}

  CascadeType.PERSIST会级联保存，所有对像都保存到数据库

  @ManyToOne(cascade = CascadeType.PERSIST)
@JoinColumn(name = "user_id")

  User user = new User();
        user.setLoginName("persistTest");
        user.setName("persistTest");
        user.setPassword("111111");
        user.setSalt("111111");
        user.setRoles("aaa");
        user.setRegisterDate(new Date());


        Task t = new Task();
        t.setTitle("persistTest");
        t.setUser(user);

        taskDao.save(t);

        logger.debug("task id={}",t.getId());
        logger.debug("user id={}",user.getId());
       
Hibernate:
    insert
    into
        t_user
        (id, login_name, name, password, register_date, roles, salt)
    values
        (null, ?, ?, ?, ?, ?, ?)
Hibernate:
    insert
    into
        t_task
        (id, description, title, user_id)
    values
        (null, ?, ?, ?)
       
15:29:16.091 [main] DEBUG com.lxz.repository.TaskDaoTest - task id=6
15:29:16.092 [main] DEBUG com.lxz.repository.TaskDaoTest - user id=3


  如果改为CascadeType.MERGE，则会出错
 
@ManyToOne(cascade = CascadeType.MERGE)
@JoinColumn(name = "user_id")

  User user = new User();
        user.setLoginName("persistTest");
        user.setName("persistTest");
        user.setPassword("111111");
        user.setSalt("111111");
        user.setRoles("aaa");
        user.setRegisterDate(new Date());


        Task t = new Task();
        t.setTitle("persistTest");
        t.setUser(user);

        taskDao.save(t);

        logger.debug("task id={}",t.getId());
        logger.debug("user id={}",user.getId());
       
Hibernate:
    insert
    into
        t_task
        (id, description, title, user_id)
    values
        (null, ?, ?, ?)
15:55:33.891 [main] WARN  o.h.e.jdbc.spi.SqlExceptionHelper - SQL Error: 23502, SQLState: 23502
15:55:33.893 [main] ERROR o.h.e.jdbc.spi.SqlExceptionHelper - NULL not allowed for column "USER_ID"; SQL statement:
insert into t_task (id, description, title, user_id) values (null, ?, ?, ?) [23502-176]