BAEL-6216 Use Mapper in Another Mapper with Mapstruct and Java (#13802)

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

@@ -0,0 +1,12 @@
+package com.baeldung.dto;
+
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter
+@Setter
+public class ArticleDTO {
+    private int id;
+    private String name;
+    private PersonDTO author;
+}

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

@@ -0,0 +1,12 @@
+package com.baeldung.entity;
+
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter
+@Setter
+public class Article {
+    private int id;
+    private String name;
+    private Person author;
+}

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

@@ -0,0 +1,20 @@
+package com.baeldung.mapper;
+
+import com.baeldung.dto.ArticleDTO;
+import com.baeldung.dto.PersonDTO;
+import com.baeldung.entity.Article;
+import com.baeldung.entity.Person;
+import org.mapstruct.Mapper;
+import org.mapstruct.factory.Mappers;
+
+@Mapper
+public interface ArticleMapper {
+    
+    ArticleMapper INSTANCE = Mappers.getMapper(ArticleMapper.class);
+    
+    ArticleDTO articleToArticleDto(Article article);
+
+    default PersonDTO personToPersonDto(Person person) {
+        return Mappers.getMapper(PersonMapper.class).personToPersonDTO(person);
+    }
+}

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

@@ -0,0 +1,16 @@
+package com.baeldung.mapper;
+
+import com.baeldung.dto.ArticleDTO;
+import com.baeldung.dto.PersonDTO;
+import com.baeldung.entity.Article;
+import com.baeldung.entity.Person;
+import org.mapstruct.Mapper;
+import org.mapstruct.factory.Mappers;
+
+@Mapper(uses = PersonMapper.class)
+public interface ArticleUsingPersonMapper {
+
+    ArticleUsingPersonMapper INSTANCE = Mappers.getMapper(ArticleUsingPersonMapper.class);
+
+    ArticleDTO articleToArticleDto(Article article);
+}

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

@@ -0,0 +1,49 @@
+package com.baeldung.mapper;
+
+import com.baeldung.dto.ArticleDTO;
+import com.baeldung.dto.CarDTO;
+import com.baeldung.entity.Article;
+import com.baeldung.entity.Car;
+import com.baeldung.entity.Person;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class ArticleMapperUnitTest {
+
+    @Test
+    public void givenArticle_whenMaps_thenProducesCorrectDto() {
+        
+        Article entity  = new Article();
+        entity.setId(1);
+        entity.setName("Mapstruct Mapping");
+        Person author = new Person();
+        author.setId("1");
+        author.setName("John");
+        entity.setAuthor(author);
+
+        ArticleDTO articleDTO = ArticleMapper.INSTANCE.articleToArticleDto(entity);
+
+        assertEquals(articleDTO.getId(), entity.getId());
+        assertEquals(articleDTO.getName(), entity.getName());
+        assertEquals(articleDTO.getAuthor().getName(), entity.getAuthor().getName());
+    }
+
+    @Test
+    public void givenArticle_whenMapsWithUses_thenProducesCorrectDto() {
+
+        Article entity  = new Article();
+        entity.setId(1);
+        entity.setName("Mapstruct Mapping");
+        Person author = new Person();
+        author.setId("1");
+        author.setName("John");
+        entity.setAuthor(author);
+
+        ArticleDTO articleDTO = ArticleUsingPersonMapper.INSTANCE.articleToArticleDto(entity);
+
+        assertEquals(articleDTO.getId(), entity.getId());
+        assertEquals(articleDTO.getName(), entity.getName());
+        assertEquals(articleDTO.getAuthor().getName(), entity.getAuthor().getName());
+    }
+}