mybatis - 使用Mybatis Plus打包批量查询报错

Question

使用Mybatis Plus打包批量查询报错

场景

我需要封装一个可以根据对象列表查询的通用方法，所以写了如下方法。注意：这个类继承了 IServiceImpl

Public List<T> listBatchByEntityList(List<T> entityList) {
    Try (final SqlSession batchSqlSession = sqlSessionBatch()) {
        Final int size = entityList.size();
        Final int batchSize = 30;
        Final List<T> result = new ArrayList<>();
        For (int i = 0; i < size; i++) {
            Final String sqlStatement = sqlStatement(SqlMethod.SELECT_LIST);
            Final List<T> list = batchSqlSession.selectList(sqlStatement, new EntityWrapper<>(entityList.get(i)));
            result.addAll(list);
            If (i >= 1 && i % batchSize == 0) {
                batchSqlSession.flushStatements();
            }
        }
        batchSqlSession.flushStatements();
        Return result;
    } catch (Exception e) {
        Throw new GlobalException("Error: Cannot execute listBatchByEntityList Method. Cause", e);
    }
}

但是，在运行时发生了异常。

Caused by: org.apache.ibatis.exceptions.PersistenceException:
### Error querying database. Cause: org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'ew' in 'class com.baomidou.mybatisplus.mapper.EntityWrapper'
### Cause: org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'ew' in 'class com.baomidou.mybatisplus.mapper.EntityWrapper'
At org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
At org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:150)
At org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:141)
At com.zx.idc.ds.common.service.impl.BaseServiceImpl.listBatchByEntityList(BaseServiceImpl.java:54)
... 37 more
Caused by: org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'ew' in 'class com.baomidou.mybatisplus.mapper.EntityWrapper'
At org.apache.ibatis.reflection.Reflector.getGetInvoker(Reflector.java:419)
At org.apache.ibatis.reflection.MetaClass.getGetInvoker(MetaClass.java:164)
At org.apache.ibatis.reflection.wrapper.BeanWrapper.getBeanProperty(BeanWrapper.java:162)
At org.apache.ibatis.reflection.wrapper.BeanWrapper.get(BeanWrapper.java:49)
At org.apache.ibatis.reflection.MetaObject.getValue(MetaObject.java:122)
At org.apache.ibatis.scripting.xmltags.DynamicContext$ContextMap.get(DynamicContext.java:94)
At org.apache.ibatis.scripting.xmltags.DynamicContext$ContextAccessor.getProperty(DynamicContext.java:108)
At org.apache.ibatis.ognl.OgnlRuntime.getProperty(OgnlRuntime.java:2685)
At org.apache.ibatis.ognl.ASTProperty.getValueBody(ASTProperty.java:114)
At org.apache.ibatis.ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:212)
At org.apache.ibatis.ognl.SimpleNode.getValue(SimpleNode.java:258)
At org.apache.ibatis.ognl.ASTNotEq.getValueBody(ASTNotEq.java:50)
At org.apache.ibatis.ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:212)
At org.apache.ibatis.ognl.SimpleNode.getValue(SimpleNode.java:258)
At org.apache.ibatis.ognl.ASTAnd.getValueBody(ASTAnd.java:61)
At org.apache.ibatis.ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:212)
At org.apache.ibatis.ognl.SimpleNode.getValue(SimpleNode.java:258)
At org.apache.ibatis.ognl.Ognl.getValue(Ognl.java:470)
At org.apache.ibatis.ognl.Ognl.getValue(Ognl.java:434)
At org.apache.ibatis.scripting.xmltags.OgnlCache.getValue(OgnlCache.java:44)
At org.apache.ibatis.scripting.xmltags.ExpressionEvaluator.evaluateBoolean(ExpressionEvaluator.java:32)
At org.apache.ibatis.scripting.xmltags.IfSqlNode.apply(IfSqlNode.java:34)
At org.apache.ibatis.scripting.xmltags.ChooseSqlNode.apply(ChooseSqlNode.java:35)
At org.apache.ibatis.scripting.xmltags.MixedSqlNode.apply(MixedSqlNode.java:33)
At org.apache.ibatis.scripting.xmltags.DynamicSqlSource.getBoundSql(DynamicSqlSource.java:41)
At org.apache.ibatis.mapping.MappedStatement.getBoundSql(MappedStatement.java:292)
At org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:134)
At org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:148)
... 39 more

有没有人遇到过这种情况？

标签： mybatis

Answer 1

这么晚才回复很抱歉。

问题是：您调用了batchSqlSession.selectList并直接使用了参数，但是在mybatis-plus（2.x）中baseMapper.selectList（@Param（“ew”）Wrapper ew）中的方法，参数具有注释@Param ，它将由 org.apache.ibatis.reflection.ParamNameResolver(line 121 @mybatis-3.4.6) 处理并包装为 ParamMap。

所以解决方法很简单：

一些代码更改：

final Map<String, Object> param = new MapperMethod.ParamMap<Object>();
EntityWrapper<T> ew = new EntityWrapper<>(entityList.get(i));
param.put("ew", ew);
param.put("param1", ew);
final List<T> list = batchSqlSession.selectList(sqlStatement, param);

完整代码如下：

public List<T> listBatchByEntityList(List<T> entityList) {
    try (final SqlSession batchSqlSession = sqlSessionBatch()) {
        final int size = entityList.size();
        final int batchSize = 30;
        final List<T> result = new ArrayList<>();
        for (int i = 0; i < size; i++) {
            final String sqlStatement = sqlStatement(SqlMethod.SELECT_LIST);
            final Map<String, Object> param = new MapperMethod.ParamMap<Object>();
            EntityWrapper<T> ew = new EntityWrapper<>(entityList.get(i));
            param.put("ew", ew);
            param.put("param1", ew);
            final List<T> list = batchSqlSession.selectList(sqlStatement, param);
            result.addAll(list);
            if (i >= 1 && i % batchSize == 0) {
                batchSqlSession.flushStatements();
            }
        }
        batchSqlSession.flushStatements();
        return result;
    } catch (Exception e) {
        throw new GlobalException("Error: Cannot execute listBatchByEntityList Method. Cause", e);
    }
}

测试正常。

顺便说一句，请随时在https://github.com/baomidou/mybatis-plus/issues上提出问题，无论使用 mybatis-plus 遇到什么错误

问候

Mybatis-plus 的成员 :)