How to map a DTO to an existing JPA entity?

Question

I\'m trying to map a Java DTO object to an existing JPA entity object without having to do something like the following:

public MyEntity mapToMyEntity(SomeDT         


        

Answer 1

You can define next class:

public class ObjectMapperUtils {

    private static ModelMapper modelMapper = new 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() {
    }

    /**
     * 
Note: outClass object must have default constructor with no arguments
     *
     * @param       type of result object.
     * @param       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 outClass type.
     */
    public static  D map(final T entity, Class outClass) {
        return modelMapper.map(entity, outClass);
    }

    /**
     * 
Note: outClass object must have default constructor with no arguments
     *
     * @param entityList list of entities that needs to be mapped
     * @param outCLass   class of result list element
     * @param         type of objects in result list
     * @param         type of entity in entityList
     * @return list of mapped object with  type.
     */
    public static  List mapAll(final Collection entityList, Class 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  D map(final S source, D destination) {
        modelMapper.map(source, destination);
        return destination;
    }
}

And use it for your needs:

MyEntity entity = ObjectMapperUtils.map(dto, existingEntity);