ModelMappersTest.java

public class ModelMappersTest {
	private static ModelMapper modelMapper;

	@BeforeClass
	public static void beforeClass() {
		modelMapper = new ModelMapper();
		modelMapper.addConverter(new AbstractConverter<A, B>() {
			@Override
			protected B convert(A a) {
				return B
					.builder()
					.num(a.getNum())
					.buttons(mapCollection(modelMapper, a.getButtonsJson(), Button.class))
					.build();
			}
		});
	}

	/**
	 * Util Method
	 */
	private static <S, D> Collection<D> mapCollection(ModelMapper modelMapper, Collection<S> sources, Class<D> destination) {
		if (CollectionUtils.isEmpty(sources) == true) {
			return Collections.emptyList();
		}

		final Collection<D> destinations = new LinkedList<>();
		for (S source : sources) {
			destinations.add(modelMapper.map(source, destination));
		}
		return destinations;
	}

	/**
	 * Util Method
	 */
	private static <D> Collection<D> mapCollection(ModelMapper modelMapper, String sources, Class<D> destinations) {
		try {
			return Jsons.convertJsonToList(sources, destinations);
		} catch (IOException e) {
			throw new RuntimeException(e);
		}
	}

	@AllArgsConstructor
	@NoArgsConstructor
	@Data
	@Builder
	public static class S1 {
		private int num;
		private String name;
		private String option;
	}

	@AllArgsConstructor
	@NoArgsConstructor
	@Data
	@Builder
	public static class S2 {
		private int num;
		private String name;
	}

	@Test
	public void test_modelmapper_simple() {
		// Given
		final S1 s1 = new S1(1, "name", "option");

		// When
		final S2 s2 = modelMapper.map(s1, S2.class);

		// Then
		Assert.assertEquals(s1.getNum(), s2.getNum());
		Assert.assertEquals(s1.getName(), s2.getName());
	}

	@AllArgsConstructor
	@NoArgsConstructor
	@Data
	@Builder
	public static class A {
		private int num = 1;
		private String buttonsJson = "[{\"name\":\"A\"}]";
	}

	@AllArgsConstructor
	@NoArgsConstructor
	@Data
	@Builder
	public static class Button {
		private String name;
	}

	@AllArgsConstructor
	@NoArgsConstructor
	@Data
	@Builder
	public static class B {
		private int num = 1;
		private Collection<Button> buttons;
	}

	@Test
	public void test_modelmapper() {
		// Given
		final A a = new A(10, "[{\"name\":\"A\"}]");

		// When
		final B b = modelMapper.map(a, B.class);

		// Then
		Assert.assertEquals(10, b.getNum());
		Assert.assertEquals("A", b.getButtons().iterator().next().getName());
	}

	@Test
	public void test_modelmapper_collection() {
		// Given
		final Collection<A> as = Arrays.asList(new A(1, "[{\"name\":\"A\"}]"),
			new A(2, "[{\"name\":\"B\"}]"));

		// When
		final Collection<B> bs = mapCollection(modelMapper, as, B.class);

		// Then
		final Iterator<B> bIterator = bs.iterator();
		final B firstB = bIterator.next();
		Assert.assertEquals(1, firstB.getNum());
		Assert.assertEquals("A", firstB.getButtons().iterator().next().getName());
		final B secondB = bIterator.next();
		Assert.assertEquals(2, secondB.getNum());
		Assert.assertEquals("B", secondB.getButtons().iterator().next().getName());
	}
}