BAEL 4092 - code samples for the article (#11235)

* BAEL-4092 initial import for code samples

* BAEL-4092 update code samples

* BAEL-4092 align code samples with the article

* BAEL-4092 some naming and formatting update

* BAEL-4092 fix tests

* BAEL-4092 remove url line in readme

* BAEL-4092 change formatting to fix indentations

* BAEL-4092 fix the typo in the package name

* BAEL-4092 fix pmd violations

* BAEL-4092 fix the test method namings according to convention

* BAEL-4092 add empty spaces on tests to make it more readable

* BAEL-4092 move the code samples from its own module into libraries6

* BAEL-4092 use the latest version of ModelMapper

Co-authored-by: Yavuz Tas <ytas@vwd.com>

libraries-6/pom.xml

@@ -106,6 +106,11 @@
             <artifactId>libphonenumber</artifactId>
             <version>${libphonenumber.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.modelmapper</groupId>
+            <artifactId>modelmapper</artifactId>
+            <version>${org.modelmapper.version}</version>
+        </dependency>
     </dependencies>
 
     <repositories>
@@ -149,6 +154,7 @@
         <rserve.version>1.8.1</rserve.version>
         <commons-collections4.version>4.4</commons-collections4.version>
         <libphonenumber.version>8.12.9</libphonenumber.version>
+        <org.modelmapper.version>2.4.4</org.modelmapper.version>
     </properties>
 
-</project>
+</project>

libraries-6/src/main/java/com/baeldung/modelmapper/domain/Game.java

@@ -0,0 +1,74 @@
+package com.baeldung.modelmapper.domain;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public class Game {
+
+    private Long id;
+    private String name;
+    private Long timestamp;
+
+    private Player creator;
+    private final List<Player> players = new ArrayList<>();
+
+    private GameSettings settings;
+
+    public Game() {
+    }
+
+    public Game(Long id, String name) {
+        this.id = id;
+        this.name = name;
+    }
+
+    public Long getId() {
+        return this.id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return this.name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public Long getTimestamp() {
+        return this.timestamp;
+    }
+
+    public void setTimestamp(Long timestamp) {
+        this.timestamp = timestamp;
+    }
+
+    public Player getCreator() {
+        return this.creator;
+    }
+
+    public void setCreator(Player creator) {
+        this.creator = creator;
+        addPlayer(creator);
+    }
+
+    public void addPlayer(Player player) {
+        this.players.add(player);
+    }
+
+    public List<Player> getPlayers() {
+        return Collections.unmodifiableList(this.players);
+    }
+
+    public GameSettings getSettings() {
+        return this.settings;
+    }
+
+    public void setSettings(GameSettings settings) {
+        this.settings = settings;
+    }
+}

libraries-6/src/main/java/com/baeldung/modelmapper/domain/GameMode.java

@@ -0,0 +1,5 @@
+package com.baeldung.modelmapper.domain;
+
+public enum GameMode {
+    NORMAL, TURBO
+}

libraries-6/src/main/java/com/baeldung/modelmapper/domain/GameSettings.java

@@ -0,0 +1,31 @@
+package com.baeldung.modelmapper.domain;
+
+public class GameSettings {
+
+    private GameMode mode;
+    private int maxPlayers;
+
+    public GameSettings() {
+    }
+
+    public GameSettings(GameMode mode, int maxPlayers) {
+        this.mode = mode;
+        this.maxPlayers = maxPlayers;
+    }
+
+    public GameMode getMode() {
+        return this.mode;
+    }
+
+    public void setMode(GameMode mode) {
+        this.mode = mode;
+    }
+
+    public int getMaxPlayers() {
+        return this.maxPlayers;
+    }
+
+    public void setMaxPlayers(int maxPlayers) {
+        this.maxPlayers = maxPlayers;
+    }
+}

libraries-6/src/main/java/com/baeldung/modelmapper/domain/Player.java

@@ -0,0 +1,41 @@
+package com.baeldung.modelmapper.domain;
+
+public class Player {
+
+    private Long id;
+    private String name;
+
+    private Game currentGame;
+
+    public Player() {
+    }
+
+    public Player(Long id, String name) {
+        this.id = id;
+        this.name = name;
+    }
+
+    public Long getId() {
+        return this.id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return this.name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public Game getCurrentGame() {
+        return this.currentGame;
+    }
+
+    public void setCurrentGame(Game currentGame) {
+        this.currentGame = currentGame;
+    }
+}

libraries-6/src/main/java/com/baeldung/modelmapper/dto/GameDTO.java

@@ -0,0 +1,92 @@
+package com.baeldung.modelmapper.dto;
+
+import com.baeldung.modelmapper.domain.GameMode;
+import java.util.List;
+
+public class GameDTO {
+
+    private Long id;
+    private String name;
+    private Long creationTime;
+
+    private String creatorId;
+    private String creator;
+
+    private int totalPlayers;
+    private List<PlayerDTO> players;
+
+    private GameMode mode;
+    private int maxPlayers;
+
+    public Long getId() {
+        return this.id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return this.name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public Long getCreationTime() {
+        return this.creationTime;
+    }
+
+    public void setCreationTime(Long creationTime) {
+        this.creationTime = creationTime;
+    }
+
+    public String getCreatorId() {
+        return this.creatorId;
+    }
+
+    public void setCreatorId(String creatorId) {
+        this.creatorId = creatorId;
+    }
+
+    public String getCreator() {
+        return this.creator;
+    }
+
+    public void setCreator(String creator) {
+        this.creator = creator;
+    }
+
+    public int getTotalPlayers() {
+        return this.totalPlayers;
+    }
+
+    public void setTotalPlayers(int totalPlayers) {
+        this.totalPlayers = totalPlayers;
+    }
+
+    public GameMode getMode() {
+        return this.mode;
+    }
+
+    public void setMode(GameMode mode) {
+        this.mode = mode;
+    }
+
+    public int getMaxPlayers() {
+        return this.maxPlayers;
+    }
+
+    public void setMaxPlayers(int maxPlayers) {
+        this.maxPlayers = maxPlayers;
+    }
+
+    public List<PlayerDTO> getPlayers() {
+        return this.players;
+    }
+
+    public void setPlayers(List<PlayerDTO> players) {
+        this.players = players;
+    }
+}

libraries-6/src/main/java/com/baeldung/modelmapper/dto/PlayerDTO.java

@@ -0,0 +1,33 @@
+package com.baeldung.modelmapper.dto;
+
+public class PlayerDTO {
+
+    private Long id;
+    private String name;
+
+    private GameDTO currentGame;
+
+    public Long getId() {
+        return this.id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return this.name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public GameDTO getCurrentGame() {
+        return this.currentGame;
+    }
+
+    public void setCurrentGame(GameDTO currentGame) {
+        this.currentGame = currentGame;
+    }
+}

libraries-6/src/main/java/com/baeldung/modelmapper/repository/GameRepository.java

@@ -0,0 +1,28 @@
+package com.baeldung.modelmapper.repository;
+
+import com.baeldung.modelmapper.domain.Game;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Sample in-memory Game Repository
+ */
+public class GameRepository {
+
+    private final List<Game> gameStore = new ArrayList<>();
+
+    public GameRepository() {
+        // initialize some test data
+        this.gameStore.add(new Game(1L, "Game 1"));
+        this.gameStore.add(new Game(2L, "Game 2"));
+        this.gameStore.add(new Game(3L, "Game 3"));
+    }
+
+    public Game findById(Long id) {
+        return this.gameStore.stream()
+          .filter(g -> g.getId().equals(id))
+          .findFirst()
+          .orElseThrow(() -> new RuntimeException("No Game found"));
+    }
+
+}

libraries-6/src/test/java/com/baeldung/modelmapper/ModelMapperUnitTest.java

@@ -0,0 +1,270 @@
+package com.baeldung.modelmapper;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+import com.baeldung.modelmapper.domain.Game;
+import com.baeldung.modelmapper.domain.GameMode;
+import com.baeldung.modelmapper.domain.GameSettings;
+import com.baeldung.modelmapper.domain.Player;
+import com.baeldung.modelmapper.dto.GameDTO;
+import com.baeldung.modelmapper.dto.PlayerDTO;
+import com.baeldung.modelmapper.repository.GameRepository;
+import java.time.Instant;
+import java.util.Collection;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.modelmapper.Condition;
+import org.modelmapper.Conditions;
+import org.modelmapper.Converter;
+import org.modelmapper.ModelMapper;
+import org.modelmapper.Provider;
+import org.modelmapper.TypeMap;
+import org.modelmapper.convention.MatchingStrategies;
+
+public class ModelMapperUnitTest {
+
+    ModelMapper mapper;
+    GameRepository gameRepository;
+
+    @BeforeEach
+    public void setup() {
+        this.mapper = new ModelMapper();
+        this.gameRepository = new GameRepository();
+    }
+
+    @Test
+    public void whenMapGameWithExactMatch_thenConvertsToDTO() {
+        // when similar source object is provided
+        Game game = new Game(1L, "Game 1");
+        GameDTO gameDTO = this.mapper.map(game, GameDTO.class);
+
+        // then it maps without property mapper
+        assertEquals(game.getId(), gameDTO.getId());
+        assertEquals(game.getName(), gameDTO.getName());
+    }
+
+    @Test
+    public void whenMapGameWithBasicPropertyMapping_thenConvertsToDTO() {
+        // setup
+        TypeMap<Game, GameDTO> propertyMapper = this.mapper.createTypeMap(Game.class, GameDTO.class);
+        propertyMapper.addMapping(Game::getTimestamp, GameDTO::setCreationTime);
+
+        // when field names are different
+        Game game = new Game(1L, "Game 1");
+        game.setTimestamp(Instant.now().getEpochSecond());
+        GameDTO gameDTO = this.mapper.map(game, GameDTO.class);
+
+        // then it maps via property mapper
+        assertEquals(game.getId(), gameDTO.getId());
+        assertEquals(game.getName(), gameDTO.getName());
+        assertEquals(game.getTimestamp(), gameDTO.getCreationTime());
+    }
+
+    @Test
+    public void whenMapGameWithDeepMapping_thenConvertsToDTO() {
+        // setup
+        TypeMap<Game, GameDTO> propertyMapper = this.mapper.createTypeMap(Game.class, GameDTO.class);
+        // add deep mapping to flatten source's Player into name in destination
+        propertyMapper.addMappings(
+          mapper -> mapper.map(src -> src.getCreator().getName(), GameDTO::setCreator)
+        );
+
+        // when map between different hierarchies
+        Game game = new Game(1L, "Game 1");
+        game.setCreator(new Player(1L, "John"));
+        GameDTO gameDTO = this.mapper.map(game, GameDTO.class);
+
+        // then
+        assertEquals(game.getId(), gameDTO.getId());
+        assertEquals(game.getName(), gameDTO.getName());
+        assertEquals(game.getCreator().getName(), gameDTO.getCreator());
+    }
+
+    @Test
+    public void whenMapGameWithDifferentTypedProperties_thenConvertsToDTO() {
+        // setup
+        TypeMap<Game, GameDTO> propertyMapper = this.mapper.createTypeMap(Game.class, GameDTO.class);
+        propertyMapper.addMappings(mapper -> mapper.map(src -> src.getCreator().getId(), GameDTO::setCreatorId));
+
+        // when map different typed properties
+        Game game = new Game(1L, "Game 1");
+        game.setCreator(new Player(1L, "John"));
+        GameDTO gameDTO = this.mapper.map(game, GameDTO.class);
+
+        // then it converts between types
+        assertEquals(game.getId(), gameDTO.getId());
+        assertEquals(game.getName(), gameDTO.getName());
+        assertEquals("1", gameDTO.getCreatorId());
+    }
+
+    @Test
+    public void whenMapGameWithSkipIdProperty_thenConvertsToDTO() {
+        // setup
+        TypeMap<Game, GameDTO> propertyMapper = this.mapper.createTypeMap(Game.class, GameDTO.class);
+        propertyMapper.addMappings(mapper -> mapper.skip(GameDTO::setId));
+
+        // when id is skipped
+        Game game = new Game(1L, "Game 1");
+        GameDTO gameDTO = this.mapper.map(game, GameDTO.class);
+
+        // then destination id is null
+        assertNull(gameDTO.getId());
+        assertEquals(game.getName(), gameDTO.getName());
+    }
+
+    @Test
+    public void whenMapGameWithCustomConverter_thenConvertsToDTO() {
+        // setup
+        TypeMap<Game, GameDTO> propertyMapper = this.mapper.createTypeMap(Game.class, GameDTO.class);
+        Converter<Collection, Integer> collectionToSize = c -> c.getSource().size();
+        propertyMapper.addMappings(
+          mapper -> mapper.using(collectionToSize).map(Game::getPlayers, GameDTO::setTotalPlayers)
+        );
+
+        // when collection to size converter is provided
+        Game game = new Game(1L, "Game 1");
+        game.setCreator(new Player(1L, "John"));
+        game.addPlayer(new Player(2L, "Bob"));
+        GameDTO gameDTO = this.mapper.map(game, GameDTO.class);
+
+        // then it maps the size to a custom field
+        assertEquals(game.getId(), gameDTO.getId());
+        assertEquals(game.getName(), gameDTO.getName());
+        assertEquals(game.getPlayers().size(), gameDTO.getTotalPlayers());
+    }
+
+    @Test
+    public void whenUsingProvider_thenMergesGameInstances() {
+        // setup
+        TypeMap<Game, Game> propertyMapper = this.mapper.createTypeMap(Game.class, Game.class);
+        // a provider to fetch a Game instance from a repository
+        Provider<Game> gameProvider = p -> this.gameRepository.findById(1L);
+        propertyMapper.setProvider(gameProvider);
+
+        // when a state for update is given
+        Game update = new Game(1L, "Game Updated!");
+        update.setCreator(new Player(1L, "John"));
+        Game updatedGame = this.mapper.map(update, Game.class);
+
+        // then it merges the updates over on the provided instance
+        assertEquals(1L, updatedGame.getId().longValue());
+        assertEquals("Game Updated!", updatedGame.getName());
+        assertEquals("John", updatedGame.getCreator().getName());
+    }
+
+    @Test
+    public void whenUsingConditionalIsNull_thenMergesGameInstancesWithoutOverridingId() {
+        // setup
+        TypeMap<Game, Game> propertyMapper = this.mapper.createTypeMap(Game.class, Game.class);
+        propertyMapper.setProvider(p -> this.gameRepository.findById(2L));
+        propertyMapper.addMappings(mapper -> mapper.when(Conditions.isNull()).skip(Game::getId, Game::setId));
+
+        // when game has no id
+        Game update = new Game(null, "Not Persisted Game!");
+        Game updatedGame = this.mapper.map(update, Game.class);
+
+        // then destination game id is not overwritten
+        assertEquals(2L, updatedGame.getId().longValue());
+        assertEquals("Not Persisted Game!", updatedGame.getName());
+    }
+
+    @Test
+    public void whenUsingCustomConditional_thenConvertsDTOSkipsZeroTimestamp() {
+        // setup
+        TypeMap<Game, GameDTO> propertyMapper = this.mapper.createTypeMap(Game.class, GameDTO.class);
+        Condition<Long, Long> hasTimestamp = ctx -> ctx.getSource() != null && ctx.getSource() > 0;
+        propertyMapper.addMappings(mapper -> mapper.when(hasTimestamp).map(Game::getTimestamp, GameDTO::setCreationTime));
+
+        // when game has zero timestamp
+        Game game = new Game(1L, "Game 1");
+        game.setTimestamp(0L);
+        GameDTO gameDTO = this.mapper.map(game, GameDTO.class);
+
+        // then timestamp field is not mapped
+        assertEquals(game.getId(), gameDTO.getId());
+        assertEquals(game.getName(), gameDTO.getName());
+        assertNotEquals(0L, gameDTO.getCreationTime());
+        assertNull(gameDTO.getCreationTime());
+
+        // when game has timestamp greater than zero
+        game.setTimestamp(Instant.now().getEpochSecond());
+        gameDTO = this.mapper.map(game, GameDTO.class);
+
+        // then timestamp field is mapped
+        assertEquals(game.getId(), gameDTO.getId());
+        assertEquals(game.getName(), gameDTO.getName());
+        assertEquals(game.getTimestamp(), gameDTO.getCreationTime());
+        assertNotNull(gameDTO.getCreationTime());
+    }
+
+    @Test
+    public void whenUsingLooseMappingStrategy_thenConvertsToDomainAndDTO() {
+        // setup
+        this.mapper.getConfiguration().setMatchingStrategy(MatchingStrategies.LOOSE);
+
+        // when dto has flat fields for GameSetting
+        GameDTO gameDTO = new GameDTO();
+        gameDTO.setId(1L);
+        gameDTO.setName("Game 1");
+        gameDTO.setMode(GameMode.TURBO);
+        gameDTO.setMaxPlayers(8);
+        Game game = this.mapper.map(gameDTO, Game.class);
+
+        // then it converts to inner objects without property mapper
+        assertEquals(gameDTO.getId(), game.getId());
+        assertEquals(gameDTO.getName(), game.getName());
+        assertEquals(gameDTO.getMode(), game.getSettings().getMode());
+        assertEquals(gameDTO.getMaxPlayers(), game.getSettings().getMaxPlayers());
+
+        // when the GameSetting's field names match
+        game = new Game(1L, "Game 1");
+        game.setSettings(new GameSettings(GameMode.NORMAL, 6));
+        gameDTO = this.mapper.map(game, GameDTO.class);
+
+        // then it flattens the fields on dto
+        assertEquals(game.getId(), gameDTO.getId());
+        assertEquals(game.getName(), gameDTO.getName());
+        assertEquals(game.getSettings().getMode(), gameDTO.getMode());
+        assertEquals(game.getSettings().getMaxPlayers(), gameDTO.getMaxPlayers());
+    }
+
+    @Test
+    public void whenConfigurationSkipNullEnabled_thenConvertsToDTO() {
+        // setup
+        this.mapper.getConfiguration().setSkipNullEnabled(true);
+        TypeMap<Game, Game> propertyMap = this.mapper.createTypeMap(Game.class, Game.class);
+        propertyMap.setProvider(p -> this.gameRepository.findById(2L));
+
+        // when game has no id
+        Game update = new Game(null, "Not Persisted Game!");
+        Game updatedGame = this.mapper.map(update, Game.class);
+
+        // then destination game id is not overwritten
+        assertEquals(2L, updatedGame.getId().longValue());
+        assertEquals("Not Persisted Game!", updatedGame.getName());
+    }
+
+    @Test
+    public void whenConfigurationPreferNestedPropertiesDisabled_thenConvertsCircularReferencedToDTO() {
+        // setup
+        this.mapper.getConfiguration().setPreferNestedProperties(false);
+
+        // when game has circular reference: Game -> Player -> Game
+        Game game = new Game(1L, "Game 1");
+        Player player = new Player(1L, "John");
+        player.setCurrentGame(game);
+        game.setCreator(player);
+        GameDTO gameDTO = this.mapper.map(game, GameDTO.class);
+
+        // then it resolves without any exception
+        assertEquals(game.getId(), gameDTO.getId());
+        assertEquals(game.getName(), gameDTO.getName());
+        PlayerDTO playerDTO = gameDTO.getPlayers().get(0);
+        assertEquals(player.getId(), playerDTO.getId());
+        assertEquals(player.getCurrentGame().getId(), playerDTO.getCurrentGame().getId());
+    }
+
+}