一、问题复盘
mybatis可以支持多种传参模式,本篇文章主要讲解mybatis的list集合或数组传参时遇到的一个问题。
我在做项目时碰到了这个情况,我直接使用了我们公司要求的param形式传参:
<select id="queryImIdByEmails" parameterType="java.util.List" resultType="java.lang.String">
select uid from employee where email in
<foreach item="item" collection="param1" separator="," open="(" close=")" index=""> #{item}
</foreach>
</select>
但是本地调试时报了这个错误:
org.apache.ibatis.binding.BindingException: Parameter ‘customerIdList’ not found. Available parameters are [collection, list]
二、错误原因:
集合或者数组传参给mybatis时,mybatis会使用map来封装参数,如果是list传参时,map的默认key为list,数组传参时,map默认key为array,在不指定传参名称时,必须使用默认的key为sql中collection的值,所以我使collection=param1会报以上错误。
三、如何解决:
1.在Dao层的的xml中直接写默认的key值,如下:
<select id="queryImIdByEmails" parameterType="java.util.List" resultType="java.lang.String">
select uid from employee where email in
<foreach item="item" collection="list" separator="," open="(" close=")" index=""> #{item}
</foreach>
</select>
2.在Dao层中指定传参名称时使用@Param注解来指定参数名称,我这里指定的时param1,你可以任意命名。
List<String> selectCustomerCountList(@Param("param1") List customerIdList);
XML文件:
<select id="queryImIdByEmails" parameterType="java.util.List" resultType="java.lang.String">
select uid from employee where email in
<foreach item="item" collection="param1" separator="," open="(" close=")" index=""> #{item}
</foreach>
</select>
3.自己直接在service层将list封装为map传给mybatis,这时的map的key可以自己任意定义。
service层
public List<String> queryImIdByEmails(List<String> emails) {
Map map = new HashMap();
map.put("emails", emails);
return employeeDao.queryImIdByEmails(maps);
}
DAO层:
List<String> queryImIdByEmails(Map map);
XML文件:
<select id="queryImIdByEmails" parameterType="java.util.Map" resultType="java.lang.String">
select uid from employee where email in
<foreach item="item" collection="emails" separator="," open="(" close=")" index=""> #{item}
</foreach>
</select>
原文地址:https://www.iteye/blog/chenzhou123520-1921284
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