Adds after / before mapping example (#7518)

mapstruct/src/main/java/com/baeldung/dto/CarDTO.java

@@ -8,4 +8,5 @@ import lombok.Setter;
 public class CarDTO {
     private int id;
     private String name;
+    private FuelType fuelType;
 }

mapstruct/src/main/java/com/baeldung/dto/FuelType.java

@@ -0,0 +1,5 @@
+package com.baeldung.dto;
+
+public enum FuelType {
+    ELECTRIC, BIO_DIESEL
+}

mapstruct/src/main/java/com/baeldung/entity/BioDieselCar.java

@@ -0,0 +1,4 @@
+package com.baeldung.entity;
+
+public class BioDieselCar extends Car {
+}

mapstruct/src/main/java/com/baeldung/entity/ElectricCar.java

@@ -0,0 +1,4 @@
+package com.baeldung.entity;
+
+public class ElectricCar extends Car {
+}

mapstruct/src/main/java/com/baeldung/mapper/CarsMapper.java

@@ -0,0 +1,32 @@
+package com.baeldung.mapper;
+
+import org.mapstruct.AfterMapping;
+import org.mapstruct.BeforeMapping;
+import org.mapstruct.Mapper;
+import org.mapstruct.MappingTarget;
+
+import com.baeldung.dto.CarDTO;
+import com.baeldung.dto.FuelType;
+import com.baeldung.entity.BioDieselCar;
+import com.baeldung.entity.Car;
+import com.baeldung.entity.ElectricCar;
+
+@Mapper
+public abstract class CarsMapper {
+
+    @BeforeMapping
+    protected void enrichDTOWithFuelType(Car car, @MappingTarget CarDTO carDto) {
+        if (car instanceof ElectricCar)
+            carDto.setFuelType(FuelType.ELECTRIC);
+        if (car instanceof BioDieselCar)
+            carDto.setFuelType(FuelType.BIO_DIESEL);
+    }
+
+    @AfterMapping
+    protected void convertNameToUpperCase(@MappingTarget CarDTO carDto) {
+        carDto.setName(carDto.getName().toUpperCase());
+    }
+
+    public abstract CarDTO toCarDto(Car car);
+
+}

mapstruct/src/test/java/com/baeldung/mapper/CarsMapperUnitTest.java

@@ -0,0 +1,42 @@
+package com.baeldung.mapper;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.jupiter.api.Test;
+import org.mapstruct.factory.Mappers;
+
+import com.baeldung.dto.CarDTO;
+import com.baeldung.dto.FuelType;
+import com.baeldung.entity.BioDieselCar;
+import com.baeldung.entity.Car;
+import com.baeldung.entity.ElectricCar;
+
+class CarsMapperUnitTest {
+
+    private CarsMapper sut = Mappers.getMapper(CarsMapper.class);
+
+    @Test
+    void testGivenSubTypeElectric_mapsModifiedFieldsToSuperTypeDto_whenBeforeAndAfterMappingMethodscarCalled() {
+        Car car = new ElectricCar();
+        car.setId(12);
+        car.setName("Tesla_Model_C");
+        
+        CarDTO carDto = sut.toCarDto(car);
+        
+        assertEquals("TESLA_MODEL_C", carDto.getName());
+        assertEquals(FuelType.ELECTRIC, carDto.getFuelType());
+    }
+    
+    @Test
+    void testGivenSubTypeBioDiesel_mapsModifiedFieldsToSuperTypeDto_whenBeforeAndAfterMappingMethodscarCalled() {
+        Car car = new BioDieselCar();
+        car.setId(11);
+        car.setName("Tesla_Model_X");
+        
+        CarDTO carDto = sut.toCarDto(car);
+        
+        assertEquals("TESLA_MODEL_X", carDto.getName());
+        assertEquals(FuelType.BIO_DIESEL, carDto.getFuelType());
+    }
+
+}