How to update the field to null by mybatis plus
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Mybatis plus updates the field to null. By default, you cannot update the field to null using the update method that comes with mybatis plus without any processing. If you want to update the field to null, you need to do the following
Annotate the required fields with @ TableField and set the properties
UpdateStrategy = FieldStrategy.IGNORED
The test code is the following database table
Entity class package com.sbmp.bean;import java.time.LocalDate;import com.baomidou.mybatisplus.annotation.IdType;import com.baomidou.mybatisplus.annotation.TableId;import lombok.Data;@Datapublic class Userinfo {/ * primary key id * / @ TableId (type = IdType.AUTO) private Integer id; / * * | * name * / private String name / * * Birthday * / private LocalDate birthday;} mapperpackage com.sbmp.mapper;import com.baomidou.mybatisplus.core.mapper.BaseMapper;import com.sbmp.bean.Userinfo;public interface UserinfoMapper extends BaseMapper {} controllerpackage com.sbmp.controller;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import com.sbmp.bean.Userinfo;import com.sbmp.mapper.UserinfoMapper @ RestControllerpublic class UserinfoController {@ Autowired private UserinfoMapper userinfoMapper; @ RequestMapping ("/ info") public String info () {Userinfo info = new Userinfo (); info.setId (1); info.setBirthday (null); info.setName ("Xue Baochai"); userinfoMapper.updateById (info) Return "successful";}} run the test
See if Xue Baochai's birthday can be updated to empty.
Look, the printed sql does not have the splicing of birthday = null. This is the default.
If you want to concatenate birthday = null, you need to add this configuration to the birthday field
@ TableField (updateStrategy = FieldStrategy.IGNORED)
The modified code is as follows
Package com.sbmp.bean;import java.time.LocalDate;import com.baomidou.mybatisplus.annotation.FieldStrategy;import com.baomidou.mybatisplus.annotation.IdType;import com.baomidou.mybatisplus.annotation.TableField;import com.baomidou.mybatisplus.annotation.TableId;import lombok.Data;@Datapublic class Userinfo {/ * primary key id * / @ TableId (type = IdType.AUTO) private Integer id / * * | * name * / private String name; / * * birthday * / @ TableField (updateStrategy = FieldStrategy.IGNORED) private LocalDate birthday;} run the test
Birthday = null updated successfully this time
@ TableField partial attribute description
Look at the official document updateStrategy for handling updates; similarly, use insertStrategy when adding
Involving where conditional processing using whereStrategy
FieldStrategy description
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