Merge pull request #9147 from sasam0320/BAEL-3986

BAEL 3986 - mapping lists using ModelMapper

java-collections-conversions-2/pom.xml

@@ -20,6 +20,23 @@
             <artifactId>commons-lang3</artifactId>
             <version>${commons-lang3.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.modelmapper</groupId>
+            <artifactId>modelmapper</artifactId>
+            <version>${modelmapper.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.hamcrest</groupId>
+            <artifactId>hamcrest</artifactId>
+            <version>${hamcrest.version}</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>

java-collections-conversions-2/src/main/java/com/baeldung/modelmapper/MapperUtil.java

@@ -0,0 +1,32 @@
+package com.baeldung.modelmapper;
+
+import org.modelmapper.ModelMapper;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+/**
+ * This is a helper class that contains method for custom mapping of the users list.
+ * Initially, an instance of ModelMapper was created.
+ *
+ * @author Sasa Milenkovic
+ */
+public class MapperUtil {
+
+    private static ModelMapper modelMapper = new ModelMapper();
+
+
+    private MapperUtil() {
+
+
+    }
+
+    public static <S, T> List<T> mapList(List<S> source, Class<T> targetClass) {
+
+        return source
+                .stream()
+                .map(element -> modelMapper.map(element, targetClass))
+                .collect(Collectors.toList());
+    }
+
+}

java-collections-conversions-2/src/main/java/com/baeldung/modelmapper/User.java

@@ -0,0 +1,70 @@
+package com.baeldung.modelmapper;
+
+/**
+ * User model entity class
+ *
+ * @author Sasa Milenkovic
+ */
+public class User {
+
+    private String userId;
+    private String username;
+    private String email;
+    private String contactNumber;
+    private String userType;
+
+    // Standard constructors, getters and setters
+
+    public User() {
+    }
+
+    public User(String userId, String username, String email, String contactNumber, String userType) {
+        this.userId = userId;
+        this.username = username;
+        this.email = email;
+        this.contactNumber = contactNumber;
+        this.userType = userType;
+    }
+
+    public String getUserId() {
+        return userId;
+    }
+
+    public void setUserId(String userId) {
+        this.userId = userId;
+    }
+
+    public String getUsername() {
+        return username;
+    }
+
+    public void setUsername(String userName) {
+        this.username = userName;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public String getContactNumber() {
+        return contactNumber;
+    }
+
+    public void setContactNumber(String contactNumber) {
+        this.contactNumber = contactNumber;
+    }
+
+    public String getUserType() {
+        return userType;
+    }
+
+    public void setUserType(String userType) {
+        this.userType = userType;
+    }
+
+
+}

java-collections-conversions-2/src/main/java/com/baeldung/modelmapper/UserDTO.java

@@ -0,0 +1,41 @@
+package com.baeldung.modelmapper;
+
+/**
+ * UserDTO model class
+ *
+ * @author Sasa Milenkovic
+ */
+public class UserDTO {
+
+    private String userId;
+    private String username;
+    private String email;
+
+    // getters and setters
+
+    public String getUserId() {
+        return userId;
+    }
+
+    public void setUserId(String userId) {
+        this.userId = userId;
+    }
+
+    public String getUsername() {
+        return username;
+    }
+
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+
+}

java-collections-conversions-2/src/main/java/com/baeldung/modelmapper/UserList.java

@@ -0,0 +1,21 @@
+package com.baeldung.modelmapper;
+
+import java.util.Collection;
+
+/**
+ * UserList class that contain collection of users
+ *
+ * @author Sasa Milenkovic
+ */
+public class UserList {
+
+    private Collection<User> users;
+
+    public Collection<User> getUsers() {
+        return users;
+    }
+
+    public void setUsers(Collection<User> users) {
+        this.users = users;
+    }
+}

java-collections-conversions-2/src/main/java/com/baeldung/modelmapper/UserListDTO.java

@@ -0,0 +1,21 @@
+package com.baeldung.modelmapper;
+
+import java.util.List;
+
+/**
+ * UserListDTO class that contain list of username properties
+ *
+ * @author Sasa Milenkovic
+ */
+public class UserListDTO {
+
+    private List<String> usernames;
+
+    public List<String> getUsernames() {
+        return usernames;
+    }
+
+    public void setUsernames(List<String> usernames) {
+        this.usernames = usernames;
+    }
+}

java-collections-conversions-2/src/main/java/com/baeldung/modelmapper/UsersListConverter.java

@@ -0,0 +1,23 @@
+package com.baeldung.modelmapper;
+
+import org.modelmapper.AbstractConverter;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+/**
+ * UsersListConverter class map the property data from the list of users into the list of user names.
+ *
+ * @author Sasa Milenkovic
+ */
+public class UsersListConverter extends AbstractConverter<List<User>, List<String>> {
+
+    @Override
+    protected List<String> convert(List<User> users) {
+
+        return users
+                .stream()
+                .map(User::getUsername)
+                .collect(Collectors.toList());
+    }
+}

java-collections-conversions-2/src/test/java/com/baeldung/modelmapper/UsersListMappingUnitTest.java

@@ -0,0 +1,92 @@
+package com.baeldung.modelmapper;
+
+import org.hamcrest.Matchers;
+import org.junit.Before;
+import org.junit.Test;
+import org.modelmapper.ModelMapper;
+import org.modelmapper.TypeMap;
+import org.modelmapper.TypeToken;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.hasItems;
+import static org.hamcrest.Matchers.hasProperty;
+import static org.junit.Assert.assertThat;
+
+
+/**
+ * This class has test methods of mapping Integer to Character list,
+ * mapping users list to DTO list using MapperUtil custom type method and property mapping using converter class
+ *
+ * @author Sasa Milenkovic
+ */
+public class UsersListMappingUnitTest {
+
+    private ModelMapper modelMapper;
+    private List<User> users;
+
+    @Before
+    public void init() {
+
+        modelMapper = new ModelMapper();
+
+        TypeMap<UserList, UserListDTO> typeMap = modelMapper.createTypeMap(UserList.class, UserListDTO.class);
+
+        typeMap.addMappings(mapper -> mapper.using(new UsersListConverter())
+                .map(UserList::getUsers, UserListDTO::setUsernames));
+
+        users = new ArrayList();
+        users.add(new User("b100", "user1", "user1@baeldung.com", "111-222", "USER"));
+        users.add(new User("b101", "user2", "user2@baeldung.com", "111-333", "USER"));
+        users.add(new User("b102", "user3", "user3@baeldung.com", "111-444", "ADMIN"));
+
+    }
+
+    @Test
+    public void whenInteger_thenMapToCharacter() {
+
+        List<Integer> integers = new ArrayList<Integer>();
+
+        integers.add(1);
+        integers.add(2);
+        integers.add(3);
+
+        List<Character> characters = modelMapper.map(integers, new TypeToken<List<Character>>() {
+        }.getType());
+
+        assertThat(characters, hasItems('1', '2', '3'));
+
+    }
+
+    @Test
+    public void givenUsersList_whenUseGenericType_thenMapToUserDTO() {
+
+        // Mapping lists using custom (generic) type mapping
+
+        List<UserDTO> userDtoList = MapperUtil.mapList(users, UserDTO.class);
+
+        assertThat(userDtoList, Matchers.<UserDTO>hasItem(
+                Matchers.both(hasProperty("userId", equalTo("b100")))
+                        .and(hasProperty("email", equalTo("user1@baeldung.com")))
+                        .and(hasProperty("username", equalTo("user1")))));
+
+
+    }
+
+    @Test
+    public void givenUsersList_whenUseConverter_thenMapToUsernames() {
+
+        // Mapping lists using property mapping and converter
+
+        UserList userList = new UserList();
+        userList.setUsers(users);
+        UserListDTO dtos = new UserListDTO();
+        modelMapper.map(userList, dtos);
+
+        assertThat(dtos.getUsernames(), hasItems("user1", "user2", "user3"));
+
+    }
+
+}

parent-java/pom.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project
-    xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xmlns="http://maven.apache.org/POM/4.0.0"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <artifactId>parent-java</artifactId>
@@ -45,6 +45,9 @@
         <guava.version>23.0</guava.version>
         <commons.io.version>2.6</commons.io.version>
         <jmh.version>1.19</jmh.version>
+        <modelmapper.version>2.3.7</modelmapper.version>
+        <junit.version>4.12</junit.version>
+        <hamcrest.version>2.2</hamcrest.version>
     </properties>
 
 </project>