MyBatis:枚举类型与字符串比较

问题描述

        在MyBatis的xml配置文件中，默认情况下枚举类型的属性与字符串类型的值是无法比较的，这和Date日期类型不能和""空字符串比较是一样的，会报错：

### Error querying database.  
Cause: java.lang.IllegalArgumentException: 
invalid comparison: com.constant.StatusEnum and java.lang.String
 

解决方式

类型定义

SysUser系统用户

        例如，现在有一个Gender性别为枚举类型的SysUser类，

package com.example.soil_backend.model.entity;

import com.baomidou.mybatisplus.annotation.*;

import java.io.IOException;
import java.time.LocalDateTime;
import java.io.Serializable;

import com.example.soil_backend.common.Validator;
import com.example.soil_backend.enums.GenderEnum;
import com.example.soil_backend.enums.RoleEnum;
import com.example.soil_backend.model.TbBase;
import com.fasterxml.jackson.annotation.JsonIgnore;
import lombok.Data;
import lombok.EqualsAndHashCode;
import lombok.experimental.Accessors;
import org.apache.ibatis.type.ByteArrayTypeHandler;
import org.springframework.web.multipart.MultipartFile;

/**
 * SysUser
 *
 * @author XiMumu
 * @since 2024-02-18
 */
@Data
@EqualsAndHashCode(callSuper = true)
@Accessors(chain = true)
@TableName("sys_user")
public class SysUser extends TbBase implements Serializable {
    private static final long serialVersionUID = -6472629353385247605L;
    /**
     * 用户编码ID;自增
     */
    @TableId(value = "user_id", type = IdType.AUTO)
    private Integer userId;

    /**
     * 账户名-必须为邮箱号
     */
    private String userName;

    /**
     * 账户密码
     */
    @JsonIgnore //标记在属性或者方法上，返回的json数据即不包含该属性
    private String passWord;

    /**
     * 昵称
     */
    private String nickName;

    /**
     * 手机号
     */
    private String telPhone;

    /**
     * 性别:1-男;2-女;3-未知
     */
    private GenderEnum gender;

    /**
     * 用户头像URL
     */
    @TableField(value = "photo_url",typeHandler = ByteArrayTypeHandler.class)
    private byte[] photoUrl;

    /**
     * 是否删除:1-使用中;2-已删除
     */
    @JsonIgnore //标记在属性或者方法上，返回的json数据即不包含该属性
    private Integer delFlag;

    /**
     * 用户角色[管理员:ADMIN;普通用户:COMMON]
     */
    private RoleEnum userRole;



}

Gender枚举类型

package com.example.soil_backend.enums;

import com.baomidou.mybatisplus.annotation.EnumValue;
import com.fasterxml.jackson.annotation.JsonValue;
import lombok.Getter;

/**
 * 管理员:ADMIN;普通用户:COMMON
 */
@Getter
public enum RoleEnum {
    ADMIN("ADMIN","管理员"),
    COMMON("COMMON","普通用户");

    //编码
    @EnumValue
    @JsonValue //规定返回前端的为1/2
    private final String code;

    //描述信息
    private final String desc;


    RoleEnum(String code, String desc) {
        this.code = code;
        this.desc = desc;
    }

    public static boolean isValidEnum(String code){
        for (RoleEnum roleEnum : RoleEnum.values()) {
            if (roleEnum.getCode().equals(code)){
                return true;
            }
        }
        return false;
    }



    @Override
    public String toString() {
        return "RoleEnum{" +
                "code=" + code +
                ", desc='" + desc + '\'' +
                '}';
    }


}

错误写法

        如下为原始的写法，会报错，

 <update id="insertUserByResetDelFlag">
        UPDATE sys_user
        <set>
            ...
            <if test="sysUser.gender != null and sysUser.gender != ''">
                gender = #{sysUser.gender},
            </if>
            ...
        </set>
    </update>

测试可用的写法

形式1：通过枚举字段的方法进行比较       

 <update id="insertUserByResetDelFlag">
        UPDATE sys_user
        <set>
            ...
            <if test="sysUser.gender != null and sysUser.gender != ''">
                gender = #{sysUser.gender},
            </if>
            ...
        </set>
    </update>

        需要改为以下的书写方式，

 <update id="insertUserByResetDelFlag">
        UPDATE sys_user
        <set>
            ...
            <if test="sysUser.gender != null and sysUser.gender.getCode() == 1">
                gender = 1,
            </if>
            <if test="sysUser.gender != null and sysUser.gender.getCode() == 2">
                gender = 2,
            </if>
            <if test="sysUser.gender != null and sysUser.gender.getCode() == 3">
                gender = 3,
            </if>
            ...
        </set>
</update>

形式2：通过枚举常量的方法进行比较

 <update id="insertUserByResetDelFlag">
        UPDATE sys_user
        <set>
            ...
            <if test="sysUser.gender != null and sysUser.gender.toString() == @com.example.soil_backend.enums.GenderEnum.MALE.toString()">
                gender = 1,
            </if>
            <if test="sysUser.gender != null and sysUser.gender.toString() == @com.example.soil_backend.enums.GenderEnum.FEMALE.toString()">
                gender = 2,
            </if>
            <if test="sysUser.gender != null and sysUser.gender.toString() == @com.example.soil_backend.enums.GenderEnum.UNKNOWN.toString()">
                gender = 3,
            </if>
            ...
        </set>
</update>