Support result map with discriminator in constructor mapping

Currently, discriminator is not correctly evaluated in a result map that is referenced from a constructor mapping.

Reported in https://stackoverflow.com/q/76177553/1261766

Author: harawata

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

@@ -704,8 +704,10 @@ Object createParameterizedResultObject(ResultSetWrapper rsw, Class<?> resultType
         if (constructorMapping.getNestedQueryId() != null) {
           value = getNestedQueryConstructorValue(rsw.getResultSet(), constructorMapping, columnPrefix);
         } else if (constructorMapping.getNestedResultMapId() != null) {
-          final ResultMap resultMap = configuration.getResultMap(constructorMapping.getNestedResultMapId());
-          value = getRowValue(rsw, resultMap, getColumnPrefix(columnPrefix, constructorMapping));
+          String constructorColumnPrefix = getColumnPrefix(columnPrefix, constructorMapping);
+          final ResultMap resultMap = resolveDiscriminatedResultMap(rsw.getResultSet(),
+              configuration.getResultMap(constructorMapping.getNestedResultMapId()), constructorColumnPrefix);
+          value = getRowValue(rsw, resultMap, constructorColumnPrefix);
         } else {
           final TypeHandler<?> typeHandler = constructorMapping.getTypeHandler();
           value = typeHandler.getResult(rsw.getResultSet(), prependPrefix(column, columnPrefix));

src/test/java/org/apache/ibatis/submitted/discriminator/Contract.java

@@ -0,0 +1,36 @@
+/*
+ *    Copyright 2009-2023 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.
+ *    You may obtain a copy of the License at
+ *
+ *       https://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+package org.apache.ibatis.submitted.discriminator;
+
+public class Contract {
+  private Integer id;
+  private Owner owner;
+
+  public Contract(Integer id, Owner owner) {
+    super();
+    this.id = id;
+    this.owner = owner;
+  }
+
+  public Integer getId() {
+    return id;
+  }
+
+  public Owner getOwner() {
+    return owner;
+  }
+}

src/test/java/org/apache/ibatis/submitted/discriminator/DiscriminatorTest.java

@@ -68,4 +68,25 @@ void shouldInheritResultType() {
     }
   }
 
+  @Test
+  void shouldBeAppliedToResultMapInConstructorArg() {
+    try (SqlSession sqlSession = sqlSessionFactory.openSession()) {
+      Mapper mapper = sqlSession.getMapper(Mapper.class);
+      List<Owner> owners = mapper.selectOwnersWithAVehicleConstructor();
+      assertEquals(Truck.class, owners.get(0).getVehicle().getClass());
+      assertEquals(Car.class, owners.get(1).getVehicle().getClass());
+    }
+  }
+
+  @Test
+  void shouldBeAppliedToResultMapInConstructorArgNested() {
+    try (SqlSession sqlSession = sqlSessionFactory.openSession()) {
+      Mapper mapper = sqlSession.getMapper(Mapper.class);
+      List<Contract> contracts = mapper.selectContracts();
+      assertEquals(2, contracts.size());
+      assertEquals(Truck.class, contracts.get(0).getOwner().getVehicle().getClass());
+      assertEquals(Car.class, contracts.get(1).getOwner().getVehicle().getClass());
+    }
+  }
+
 }

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

@@ -23,4 +23,8 @@ public interface Mapper {
 
   List<Owner> selectOwnersWithAVehicle();
 
+  List<Owner> selectOwnersWithAVehicleConstructor();
+
+  List<Contract> selectContracts();
+
 }

src/test/java/org/apache/ibatis/submitted/discriminator/Owner.java

@@ -1,5 +1,5 @@
 /*
- *    Copyright 2009-2022 the original author or authors.
+ *    Copyright 2009-2023 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.
@@ -20,6 +20,16 @@ public class Owner {
   private String name;
   private Vehicle vehicle;
 
+  public Owner() {
+    super();
+  }
+
+  public Owner(Integer id, Vehicle vehicle) {
+    super();
+    this.id = id;
+    this.vehicle = vehicle;
+  }
+
   public Integer getId() {
     return id;
   }

src/test/resources/org/apache/ibatis/submitted/discriminator/CreateDB.sql

@@ -1,5 +1,5 @@
 --
---    Copyright 2009-2022 the original author or authors.
+--    Copyright 2009-2023 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.
@@ -16,6 +16,7 @@
 
 drop table vehicle if exists;
 drop table owner if exists;
+drop table contract if exists;
 
 create table vehicle (
   id int,
@@ -39,3 +40,12 @@ create table owner (
 insert into owner (id, name, vehicle_type, vehicle_id) values
 (1, 'Owner1', 'truck', 2),
 (2, 'Owner2', 'car', 1);
+
+create table contract (
+    id int,
+    owner_id int
+);
+
+insert into contract (id, owner_id) values
+(11, 1),
+(12, 2);

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

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!--
 
-       Copyright 2009-2022 the original author or authors.
+       Copyright 2009-2023 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.
@@ -81,4 +81,50 @@
     where id = #{id}
   ]]></select>
 
+  <resultMap
+    type="org.apache.ibatis.submitted.discriminator.Owner"
+    id="ownerConstructorResult">
+    <constructor>
+      <idArg javaType="int" column="id" />
+      <arg javaType="org.apache.ibatis.submitted.discriminator.Vehicle"
+        resultMap="vehicleResult" columnPrefix="vhc_" />
+    </constructor>
+    <result javaType="string" column="name" />
+  </resultMap>
+
+  <select id="selectOwnersWithAVehicleConstructor"
+    resultMap="ownerConstructorResult"><![CDATA[
+    select onr.id, onr.name,
+      vhc.id vhc_id,
+      vhc.maker vhc_maker,
+      vhc.vehicle_type vhc_vehicle_type,
+      vhc.door_count vhc_door_count,
+      vhc.carrying_capacity vhc_carrying_capacity
+    from owner onr
+    left join vehicle vhc on vhc.id = onr.vehicle_id
+  ]]></select>
+
+  <resultMap
+    type="org.apache.ibatis.submitted.discriminator.Contract"
+    id="contractResult">
+    <constructor>
+      <idArg javaType="int" column="id" />
+      <arg javaType="org.apache.ibatis.submitted.discriminator.Owner"
+        resultMap="ownerConstructorResult" columnPrefix="onr_" />
+    </constructor>
+  </resultMap>
+
+  <select id="selectContracts" resultMap="contractResult"><![CDATA[
+    select ctt.id,
+      onr.id onr_id, onr.name onr_name,
+      vhc.id onr_vhc_id,
+      vhc.maker onr_vhc_maker,
+      vhc.vehicle_type onr_vhc_vehicle_type,
+      vhc.door_count onr_vhc_door_count,
+      vhc.carrying_capacity onr_vhc_carrying_capacity
+    from contract ctt
+    left join owner onr on onr.id = ctt.owner_id
+    left join vehicle vhc on vhc.id = onr.vehicle_id
+  ]]></select>
+
 </mapper>