Added ResultSetMapping for Non-Entity classes in Spring JPA

Author: rajakumar05032000

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/AbstractJpaQuery.java

@@ -23,15 +23,15 @@
 import jakarta.persistence.TupleElement;
 import jakarta.persistence.TypedQuery;
 
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.UnaryOperator;
 import java.util.stream.Collectors;
 
+import org.hibernate.jpa.spi.NativeQueryTupleTransformer;
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.data.jpa.provider.PersistenceProvider;
 import org.springframework.data.jpa.repository.EntityGraph;
@@ -51,6 +51,7 @@
 import org.springframework.jdbc.support.JdbcUtils;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
+import org.springframework.util.ReflectionUtils;
 
 /**
  * Abstract base class to implement {@link RepositoryQuery}s.
@@ -150,10 +151,55 @@ private Object doExecute(JpaQueryExecution execution, Object[] values) {
 
 		JpaParametersParameterAccessor accessor = obtainParameterAccessor(values);
 		Object result = execution.execute(this, accessor);
-
 		ResultProcessor withDynamicProjection = method.getResultProcessor().withDynamicProjection(accessor);
+		Class<?> clazz = method.getReturnedObjectType();
+		Method[] methods = ReflectionUtils.getDeclaredMethods(clazz);
+		Map<String, Method> setterMethodsMap = new ConcurrentHashMap<>();
+		for(Method method : methods)
+		{
+			String methodName = method.getName();
+			if(methodName.startsWith("set") && method.getParameterCount() == 1)
+			{
+				String fieldName = methodName.substring(3).toLowerCase();
+				setterMethodsMap.put(fieldName, method);
+			}
+		}
+		try {
+			Constructor constructor = clazz.getConstructor();
+			if(result instanceof Collection<?>)
+			{
+				Collection resultList = result instanceof List<?> ? new ArrayList<>() : new HashSet();
+				for(var item : (Iterable) result)
+				{
+					var res = getResultObject((Tuple) item, constructor, setterMethodsMap);
+					resultList.add(res);
+				}
+				return resultList;
+			}
+			else return getResultObject((Tuple) result, constructor, setterMethodsMap);
+		}
+		catch (Exception e) {}
+
 		return withDynamicProjection.processResult(result,
 				new TupleConverter(withDynamicProjection.getReturnedType(), method.isNativeQuery()));
+
+	}
+
+
+	@Nullable
+	private static Object getResultObject(Tuple item, Constructor constructor, Map<String, Method> setterMethodsMap)
+			throws InstantiationException, IllegalAccessException, InvocationTargetException {
+		var res = constructor.newInstance();
+		for(var field : item.getElements())
+		{
+			String fieldName = field.getAlias().toLowerCase();
+			if(setterMethodsMap.containsKey(fieldName))
+			{
+				Object val = item.get(fieldName);
+				setterMethodsMap.get(fieldName).invoke(res, val);
+			}
+		}
+		return res;
 	}
 
 	private JpaParametersParameterAccessor obtainParameterAccessor(Object[] values) {

spring-data-jpa/src/test/java/org/springframework/data/jpa/domain/sample/Customer.java

@@ -28,4 +28,15 @@ public class Customer {
     @Id Long id;
 
     String name;
+
+    public Customer()
+    {
+
+    }
+
+    public Customer(Long id, String name) {
+        this.id = id;
+        this.name = name;
+    }
+
 }

spring-data-jpa/src/test/java/org/springframework/data/jpa/domain/sample/CustomerDTO.java

@@ -0,0 +1,37 @@
+package org.springframework.data.jpa.domain.sample;
+
+import jakarta.persistence.Id;
+
+public class CustomerDTO {
+
+    Long id;
+
+    String name;
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    @Override
+    public String toString() {
+        return "CustomerDTO{" +
+                "id=" + id +
+                ", name='" + name + '\'' +
+                '}';
+    }
+}
+
+//public record CustomerDTO(Long id, String name) {
+//}

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/UserRepositoryFinderTests.java

@@ -37,9 +37,12 @@
 import org.springframework.data.domain.Slice;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.domain.Window;
+import org.springframework.data.jpa.domain.sample.Customer;
+import org.springframework.data.jpa.domain.sample.CustomerDTO;
 import org.springframework.data.jpa.domain.sample.Role;
 import org.springframework.data.jpa.domain.sample.User;
 import org.springframework.data.jpa.provider.PersistenceProvider;
+import org.springframework.data.jpa.repository.sample.CustomerRepository;
 import org.springframework.data.jpa.repository.sample.RoleRepository;
 import org.springframework.data.jpa.repository.sample.UserRepository;
 import org.springframework.data.jpa.repository.sample.UserRepository.IdOnly;
@@ -68,6 +71,7 @@ class UserRepositoryFinderTests {
 	@Autowired UserRepository userRepository;
 	@Autowired RoleRepository roleRepository;
 	@Autowired EntityManager em;
+	@Autowired CustomerRepository customerRepository;
 
 	PersistenceProvider provider;
 
@@ -77,6 +81,8 @@ class UserRepositoryFinderTests {
 	private Role drummer;
 	private Role guitarist;
 	private Role singer;
+	private Customer customer1;
+	private Customer customer2;
 
 	@BeforeEach
 	void setUp() {
@@ -88,15 +94,38 @@ void setUp() {
 		dave = userRepository.save(new User("Dave", "Matthews", "[email protected]", singer));
 		carter = userRepository.save(new User("Carter", "Beauford", "[email protected]", singer, drummer));
 		oliver = userRepository.save(new User("Oliver August", "Matthews", "[email protected]"));
+		customer1 = customerRepository.save(new Customer(1L,"Raja"));
+		customer2 = customerRepository.save(new Customer(2L, "Raja"));
 
 		provider = PersistenceProvider.fromEntityManager(em);
 	}
 
+
+	@Test
+	void testMapping()
+	{
+		List<CustomerDTO>  customerDTOList = customerRepository.findByNameNativeQuery2("Raja");
+		assertThat(customerDTOList.size()).isEqualTo(2);
+		System.out.println(customerDTOList);
+	}
+
+	@Test
+	void testMapping2()
+	{
+		CustomerDTO  customerDTO = customerRepository.findByNameNativeQuery3("Raja");
+		System.out.println(customerDTO);
+		assertThat(customerDTO.getId()).isEqualTo(1);
+		assertThat(customerDTO.getName()).isEqualTo("Raja");
+	}
+
+
+
 	@AfterEach
 	void clearUp() {
 
 		userRepository.deleteAll();
 		roleRepository.deleteAll();
+		customerRepository.deleteAll();
 	}
 
 	/**

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/sample/CustomerRepository.java

@@ -0,0 +1,18 @@
+package org.springframework.data.jpa.repository.sample;
+
+import org.springframework.data.jpa.domain.sample.Customer;
+import org.springframework.data.jpa.domain.sample.CustomerDTO;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
+import java.util.List;
+
+public interface CustomerRepository extends JpaRepository<Customer, Long> {
+
+    @Query(value = "select id as Id, name as name from Customer", nativeQuery = true)
+    List<CustomerDTO> findByNameNativeQuery2(@Param("name") String name);
+
+    @Query(value = "select id as Id, name as name from Customer where rownum=1", nativeQuery = true)
+    CustomerDTO findByNameNativeQuery3(@Param("name") String name);
+
+}