• 逻辑删除
  • 修改表结构
  • 配置
  • 测试删除
  • 测试查询
• 通用枚举
  • 修改表结构
  • 定义枚举
  • 配置
  • 修改实体类
  • 测试插入数据
  • 测试查询

逻辑删除

在系统开发中，有时删除操作需要实现逻辑删除，所谓逻辑删除就是将数据标记为删除，而并非真正的物理删除（非 DELETE 操作），在查询时需要携带状态条件，确保被标记的数据不被查询到。这样做的目的就是避免数据被真正的删除。

修改表结构

为 tb_user 表增加 deleted 字段，用于表示数据是否被删除，1 代表删除，0 代表未删除。

ALTER TABLE `tb_user` ADD COLUMN `deleted` int(1) NULL DEFAULT 0 COMMENT '1代表删除，0代表未删除' AFTER `version`;

同时，也修改 User 实体，增加 deleted 属性并且添加 @TableLogic 注解：

@TableLogic
private Integer deleted;

配置

application.properties：

# 逻辑已删除值(默认为 1)
mybatis-plus.global-config.db-config.logic-delete-value=1
# 逻辑未删除值(默认为 0)
mybatis-plus.global-config.db-config.logic-not-delete-value=0

测试删除

@Test
public void testDeleteById(){
    this.userMapper.deleteById(2L);
}

测试结果：

[main] [cn.itcast.mp.mapper.UserMapper.deleteById]-[DEBUG] ==> Preparing: UPDATE
tb_user SET deleted=1 WHERE id=? AND deleted=0
[main] [cn.itcast.mp.mapper.UserMapper.deleteById]-[DEBUG] ==> Parameters: 2(Long)
[main] [cn.itcast.mp.mapper.UserMapper.deleteById]-[DEBUG] <== Updates: 1

测试查询

@Test
public void testSelectById(){
    User user = this.userMapper.selectById(2L);
    System.out.println(user);
}

测试结果：

[main] [cn.itcast.mp.mapper.UserMapper.selectById]-[DEBUG] ==> Preparing: SELECT
id,user_name,password,name,age,email,version,deleted FROM tb_user WHERE id=? AND
deleted=0
[main] [cn.itcast.mp.mapper.UserMapper.selectById]-[DEBUG] ==> Parameters: 2(Long)
[main] [cn.itcast.mp.mapper.UserMapper.selectById]-[DEBUG] <== Total: 0

可见，已经实现了逻辑删除。

通用枚举

此方案解决了繁琐的配置，让 mybatis 优雅地使用枚举属性。

修改表结构

ALTER TABLE `tb_user` ADD COLUMN `sex` int(1) NULL DEFAULT 1 COMMENT '1-男，2-女' AFTER `deleted`;

定义枚举

package=cn.itcast.mp.enums;

import com.baomidou.mybatisplus.core.enums.IEnum;
import com.fasterxml.jackson.annotation.JsonValue;

public enum SexEnum implements IEnum<Integer> {
    
    MAN(1,"男"),
    WOMAN(2,"女");
    
    private int value;
    private String desc;
    
    SexEnum(int value, String desc) {
        this.value = value;
        this.desc = desc;
    }
    
    @Override
    public Integer getValue() {
        return this.value;
    }
    
    @Override
    public String toString() {
        return this.desc;
    }
}

配置

# 枚举包扫描
mybatis-plus.type-enums-package=cn.itcast.mp.enums

修改实体类

private SexEnum sex;

测试插入数据

@Test
public void testInsert(){
    User user = new User();
    user.setName("貂蝉");
    user.setUserName("diaochan");
    user.setAge(20);
    user.setEmail("diaochan@itast.cn");
    user.setVersion(1);
    
    user.setSex(SexEnum.WOMAN);
    
    int result = this.userMapper.insert(user);
    System.out.println("result = " + result);
}

测试结果：

[main] [cn.itcast.mp.mapper.UserMapper.insert]-[DEBUG] ==> Preparing: INSERT INTO
tb_user ( user_name, password, name, age, email, version, sex ) VALUES ( ?, ?, ?, ?, ?,
?, ? )
[main] [cn.itcast.mp.mapper.UserMapper.insert]-[DEBUG] ==> Parameters:
diaochan(String), 123456(String), 貂蝉(String), 20(Integer), diaochan@itast.cn(String),
1(Integer), 2(Integer)
[main] [cn.itcast.mp.mapper.UserMapper.insert]-[DEBUG] <== Updates: 1

测试查询

@Test
public void testSelectById(){
    User user = this.userMapper.selectById(2L);
    System.out.println(user);
}

测试结果：

[main] [cn.itcast.mp.mapper.UserMapper.selectById]-[DEBUG] ==> Preparing: SELECT
id,user_name,password,name,age,email,version,deleted,sex FROM tb_user WHERE id=? AND
deleted=0
[main] [cn.itcast.mp.mapper.UserMapper.selectById]-[DEBUG] ==> Parameters: 2(Long)
[main] [cn.itcast.mp.mapper.UserMapper.selectById]-[DEBUG] <== Total: 1
User(id=2, userName=lisi, password=123456, name=李四, age=30, email=test2@itcast.cn,
address=null, version=2, deleted=0, sex=女)

条件查询时也是有效的：

@Test
public void testSelectBySex() {
    QueryWrapper<User> wrapper = new QueryWrapper<>();
    wrapper.eq("sex", SexEnum.WOMAN);
    List<User> users = this.userMapper.selectList(wrapper);
    for (User user : users) {
        System.out.println(user);
    }
}

测试结果：

[main] [cn.itcast.mp.mapper.UserMapper.selectList]-[DEBUG] ==> Preparing: SELECT
id,user_name,password,name,age,email,version,deleted,sex FROM tb_user WHERE deleted=0
AND sex = ?
[main] [cn.itcast.mp.mapper.UserMapper.selectList]-[DEBUG] ==> Parameters: 2(Integer)
[main] [cn.itcast.mp.mapper.UserMapper.selectList]-[DEBUG] <== Total: 3