I am writing simple blog web application using Spring MVC framework. I am willing to add DTO
layer to my app.
I decided to use ModelMapper framework for conversion from Entity
objects to DTO
objects used in my views.
I have just one problem.
On my main page, I am showing a list of posts on my blog. In my view, it's just list of Post
(Entity) objects. I want to change it to pass a list of PostDTO
objects to my view. Is there any way to map List
of Post
objects to List
of PostDTO
object with single method call?
I was thinking about writing converter that will convert this but I am not sure it's a good way to do it.
Also, I am using Lists
of Entities
in few more places like administrative panel or comment below every Post on my page.
Link to code of my app on GitHub repository: repository
You can create util class:
public class ObjectMapperUtils {
private static final ModelMapper modelMapper;
/**
* Model mapper property setting are specified in the following block.
* Default property matching strategy is set to Strict see {@link MatchingStrategies}
* Custom mappings are added using {@link ModelMapper#addMappings(PropertyMap)}
*/
static {
modelMapper = new ModelMapper();
modelMapper.getConfiguration().setMatchingStrategy(MatchingStrategies.STRICT);
}
/**
* Hide from public usage.
*/
private ObjectMapperUtils() {
}
/**
* <p>Note: outClass object must have default constructor with no arguments</p>
*
* @param <D> type of result object.
* @param <T> type of source object to map from.
* @param entity entity that needs to be mapped.
* @param outClass class of result object.
* @return new object of <code>outClass</code> type.
*/
public static <D, T> D map(final T entity, Class<D> outClass) {
return modelMapper.map(entity, outClass);
}
/**
* <p>Note: outClass object must have default constructor with no arguments</p>
*
* @param entityList list of entities that needs to be mapped
* @param outCLass class of result list element
* @param <D> type of objects in result list
* @param <T> type of entity in <code>entityList</code>
* @return list of mapped object with <code><D></code> type.
*/
public static <D, T> List<D> mapAll(final Collection<T> entityList, Class<D> outCLass) {
return entityList.stream()
.map(entity -> map(entity, outCLass))
.collect(Collectors.toList());
}
/**
* Maps {@code source} to {@code destination}.
*
* @param source object to map from
* @param destination object to map to
*/
public static <S, D> D map(final S source, D destination) {
modelMapper.map(source, destination);
return destination;
}
}
And use it for your needs:
List<PostDTO> listOfPostDTO = ObjectMapperUtils.mapAll(listOfPosts, PostDTO.class);