idea后端报错，语句可能存在语法错误。需要检查 Mapper 文件和 SQL 查询语句是否正确，并确保正确加载相关文件。

Question

后端报错

ProductMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.mail_1.mail.mapper.ProductMapper">

    <resultMap id="productResult" type="com.mail_1.mail.entity.Product">
        <association property="type" column="typeId" select="com.mail_1.mail.mapper.SmallTypeMapper.findById"></association>
    </resultMap>

    <select id="list" parameterType="Map" resultMap="productResult">
        select * from product
        <where>
            <if test="name!=null and name!='' ">
                and name like concat('%',#{name},'%')
            </if>
        </where>
        <if test="start!=null and pageSize!=null ">
            limit #{start},#{pageSize}
        </if>
    </select>

    <select id="getTotal" parameterType="Map" resultType="Long">
        select count(*) from product
        <where>
            <if test="name!=null and name!='' ">
                and name like concat('%',#{name},'%')
            </if>
        </where>
    </select>

    <insert id="add" parameterType="com.mail_1.mail.entity.Product">
        insert into product values(null,#{name},#{price},#{stock},#{proPic},#{hot},#{swiper},#{swiperPic},#{swiperSort},#{type.id},null,#{productIntroImgs},#{productParaImgs},#{description});
    </insert>

    <update id="update" parameterType="com.mail_1.mail.entity.Product">
        update product
        <set>
            <if test="name!=null and name!=''">
                name=#{name},
            </if>
            <if test="price!=null">
                price=#{price},
                price=#{price},
            </if>
            <if test="stock!=null">
                stock=#{stock},
            </if>
            <if test="type!=null and type.id!=null">
                typeId=#{type.id},
            </if>
            <if test="proPic!=null and proPic!=''">
                proPic=#{proPic},
            </if>
            <if test="description!=null and description!=''">
                description=#{description},
            </if>
            <if test="productIntroImgs!=null and productIntroImgs!=''">
                productIntroImgs=#{productIntroImgs},
            </if>
            <if test="productParaImgs!=null and productParaImgs!=''">
                productParaImgs=#{productParaImgs},
            </if>
            <if test="swiperPic!=null and swiperPic!=''">
                swiperPic=#{swiperPic},
            </if>
            <if test="swiperSort!=null">
                swiperSort=#{swiperSort},
            </if>
        </set>
        where id=#{id}
    </update>

    <select id="findById" parameterType="Integer" resultMap="productResult">
        select * from product where id=#{id}
    </select>

</mapper>

Answer 1

你这里不是返回一个SmallType 么，

mapper中返回的是这个？