mybatis 使用foreach 数据类型不对导致报错

╰半橙微兮° 2022-03-06 05:58 213阅读 0赞

### 起因 ###

使用mybatis动态sql进行遍历条件的时候报了下面这个错误：

Caused by: java.lang.IllegalStateException: Type handler was null on parameter mapping for property '__frch_item_0'. It was either not specified and/or could not be found for the javaType (com.test.Report) : jdbcType (null) combination.
        at org.apache.ibatis.mapping.ParameterMapping$Builder.validate (ParameterMapping.java:117)
        at org.apache.ibatis.mapping.ParameterMapping$Builder.build (ParameterMapping.java:104)
        at org.apache.ibatis.builder.SqlSourceBuilder$ParameterMappingTokenHandler.buildParameterMapping (SqlSourceBuilder.java:123)
        at org.apache.ibatis.builder.SqlSourceBuilder$ParameterMappingTokenHandler.handleToken (SqlSourceBuilder.java:67)
        at org.apache.ibatis.parsing.GenericTokenParser.parse (GenericTokenParser.java:69)
        at org.apache.ibatis.builder.SqlSourceBuilder.parse (SqlSourceBuilder.java:45)
        at org.apache.ibatis.scripting.xmltags.DynamicSqlSource.getBoundSql (DynamicSqlSource.java:44)
        at org.apache.ibatis.mapping.MappedStatement.getBoundSql (MappedStatement.java:292)
        at org.apache.ibatis.executor.CachingExecutor.query (CachingExecutor.java:81)
        at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList (DefaultSqlSession.java:148)
        at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList (DefaultSqlSession.java:141)
        at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke (Method.java:498)
        at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke (SqlSessionTemplate.java:434)
        at com.sun.proxy.$Proxy57.selectList (Unknown Source)
        at org.mybatis.spring.SqlSessionTemplate.selectList (SqlSessionTemplate.java:231)

<select id="getById" parameterType="map" resultType="Report">
            select * from test
            where orderid in
            <foreach collection="idlist" item="item" index="index" open="(" separator="," close=")">
                #{item}
            </foreach>
            
        </select>

怎么找都没找到原因，最后发现这个sql之所以报错并不是这个sql写错了，而是传入的参数报错了，我认为参数是这个样子的：

{
      "name":"张三",
      "idlsit":{1,2,3}
    }

最后发现，参数是这个样子的的：

{
      "name":"张三",
      "idlsit":{Report对象,Report对象,Report对象}
    }

看到这里可能会觉得怎么可能出现这种问题，编译都不会通过，但是通过特殊的情况确实产生了，我的代码如下：

List<String> idList = reportDao.getIdList(start, end);
    
            if (null != idList && idList.size() >= 1) {
                result = orderReportDao.getById(idList, start);
            }

sql:

<select id="getIdList" parameterType="map" resultType="Report">//这个返回值类型错了
            select id from test_id
        </select>
    
        <select id="getById" parameterType="map" resultType="Report">
            select * from test
            where orderid in
            <foreach collection="idlist" item="item" index="index" open="(" separator="," close=")">
                #{item}
            </foreach>
            
        </select>

实际上在执行过程中getIdList的返回类型错了，但是没有报错误，返回值List < String > idList实际上是List < Report > idList，这竟然没有报错，可能反射有关。