Avoid corner case NPEs when mapping results

Author: harawata

src/main/java/org/apache/ibatis/executor/resultset/DefaultResultSetHandler.java

@@ -600,6 +600,10 @@ private Object getPropertyMappingValue(ResultSetWrapper rsw, MetaObject metaResu
         final String property = propertyMapping.getProperty();
         final Type javaType = property == null ? null : metaResultObject.getGenericSetterType(property).getKey();
         typeHandler = rsw.getTypeHandler(javaType, column);
+        if (typeHandler == null) {
+          throw new ExecutorException(
+              "No type handler found for '" + javaType + "' and JDBC type '" + rsw.getJdbcType(column) + "'");
+        }
       }
       return typeHandler.getResult(rs, column);
     }
@@ -1540,6 +1544,9 @@ private void createRowKeyForMappedProperties(ResultMap resultMap, ResultSetWrapp
           if (th == null) {
             th = typeHandlerRegistry.getTypeHandler(rsw.getJdbcType(column));
           }
+          if (th == null) {
+            th = ObjectTypeHandler.INSTANCE;
+          }
           final Object value = th.getResult(rsw.getResultSet(), column);
           if (value != null || configuration.isReturnInstanceForEmptyRow()) {
             cacheKey.update(column);

src/test/java/org/apache/ibatis/submitted/typehandler/Mapper.java

@@ -23,6 +23,7 @@
 import org.apache.ibatis.annotations.Options;
 import org.apache.ibatis.annotations.Param;
 import org.apache.ibatis.annotations.Result;
+import org.apache.ibatis.annotations.ResultMap;
 import org.apache.ibatis.annotations.Results;
 import org.apache.ibatis.annotations.Select;
 import org.apache.ibatis.submitted.typehandler.Product.ProductId;
@@ -70,4 +71,13 @@ public interface Mapper {
 
   @Insert({ "insert into vague (vague) values (#{bean})" })
   int insertVague(@Param("bean") VagueBean bean);
+
+  @Result(property = "id", column = "id")
+  @Result(property = "vague", column = "vague")
+  @Select("select * from vague where id = #{id}")
+  VagueBean selectVague(Integer id);
+
+  @ResultMap("vagueRM")
+  @Select("select * from vague where id = #{id}")
+  VagueBean selectVagueNested(Integer id);
 }

src/test/java/org/apache/ibatis/submitted/typehandler/TypeHandlerTest.java

@@ -18,6 +18,7 @@
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assertions.fail;
 
 import java.io.Reader;
@@ -29,6 +30,7 @@
 import java.util.Map;
 
 import org.apache.ibatis.BaseDataTest;
+import org.apache.ibatis.executor.ExecutorException;
 import org.apache.ibatis.io.Resources;
 import org.apache.ibatis.session.SqlSession;
 import org.apache.ibatis.session.SqlSessionFactory;
@@ -218,4 +220,28 @@ void shouldThrowProperExceptionWhenNoHandlerFoundForParam() {
     }
   }
 
+  @Test
+  void shouldThrowProperExceptionWhenNoHandlerFoundForResult() {
+    addMapper();
+    try (SqlSession sqlSession = sqlSessionFactory.openSession()) {
+      Mapper mapper = sqlSession.getMapper(Mapper.class);
+      mapper.selectVague(1);
+      fail("Should throw exception");
+    } catch (Exception e) {
+      assertThat(e).cause().isExactlyInstanceOf(ExecutorException.class)
+          .hasMessage("No type handler found for 'java.util.Set<?>' and JDBC type 'OTHER'");
+    }
+  }
+
+  @Test
+  void shouldCreateRowKeyNotThrowNpe() {
+    addMapper();
+    try (SqlSession sqlSession = sqlSessionFactory.openSession()) {
+      Mapper mapper = sqlSession.getMapper(Mapper.class);
+      VagueBean bean = mapper.selectVagueNested(1);
+      assertEquals(1, bean.getId());
+      assertTrue(bean.getVague().isEmpty());
+    }
+  }
+
 }

src/test/resources/org/apache/ibatis/submitted/typehandler/Mapper.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!--
 
-       Copyright 2009-2022 the original author or authors.
+       Copyright 2009-2025 the original author or authors.
 
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
@@ -32,4 +32,13 @@
         select * from product where name = #{name}
     </select>
 
+    <resultMap
+        type="org.apache.ibatis.submitted.typehandler.VagueBean"
+        id="vagueRM">
+        <result property="id" column="id" />
+        <collection property="vague" ofType="string"
+            javaType="java.util.HashSet">
+            <result column="vague" />
+        </collection>
+    </resultMap>
 </mapper>