I am trying to map JsonNullable<List<ChildRequestTO> to Nullable<List<ChildRequestDO>> (see full code below) with mapstruct 1.4.2.Final and I am facing the following error: error: Nullable<List<ChildRequestDO>> does not have an accessible constructor. If I add a constructor for Nullable like
public Nullable(T value) {
this.value = value;
this.isPresent = true;
}
then I get the following error error: Unmapped target property: "value". Mapping from property "JsonNullable<List<ChildRequestTO>> products" to "Nullable<List<ChildRequestDO>> products".
How do I map complex wrapped types in a generic way?
The following mapping code (part of ChildRequestMapper class and applied in ObjectRequestMapper) solves the problem but I want to solve it in a more generic way:
@Named("mappingHelper")
default Nullable<List<ChildRequestDO>> customMapToDOs(JsonNullable<List<ChildRequestTO>> input) {
if (JsonNullable.undefined().equals(input)) {
return Nullable.undefined();
}
if (input.get() == null) {
return Nullable.of(null);
}
var output= input.get()
.stream()
.map(this::mapToDO)
.collect(Collectors.toList());
return Nullable.of(output);
}
Changing the NullableMapper to the code below does not work/compile because I do not know how to tell mapstruct to look for the appropriate mapper to map from T to X.
public static <T, X> Nullable<X> jsonNullableToNullable(JsonNullable<T> jsonNullable) {
if (jsonNullable.isPresent()) {
return Nullable.of(jsonNullable.get());
}
return Nullable.undefined();
}
Full code:
@Mapper(
unmappedTargetPolicy = ReportingPolicy.ERROR,
uses = {ChildRequestMapper.class, NullableMapper.class}
)
public interface ObjectRequestMapper {
@Mapping(target = "slots", source = "slots", qualifiedByName = "mapToSlotDOs")
ModifyObjectRequestDO mapToDO(ModifyObjectRequestTO input);
}
@Mapper(unmappedTargetPolicy = ReportingPolicy.ERROR)
public interface ChildRequestMapper {
ChildRequestDO mapToDO(ChildRequestTO input);
}
public class NullableMapper {
public static <T> Nullable<T> jsonNullableToNullable(JsonNullable<T> jsonNullable) {
if (jsonNullable.isPresent()) {
return Nullable.of(jsonNullable.get());
}
return Nullable.undefined();
}
}
public class ModifyObjectRequestTO {
private JsonNullable<String> name = JsonNullable.undefined();
private JsonNullable<List<ChildRequestTO>> children = JsonNullable.undefined();
}
public class ModifyObjectRequestDO {
private Nullable<String> name = Nullable.undefined();
private Nullable<List<ChildRequestDO>> children = Nullable.undefined();
}
public class Nullable<T> {
private static final Nullable<?> UNDEFINED = new Nullable<>(null, false);
private final T value;
private final boolean isPresent;
private Nullable(T value, boolean isPresent) {
this.value = value;
this.isPresent = isPresent;
}
public static <T> Nullable<T> undefined() {
@SuppressWarnings("unchecked")
Nullable<T> t = (Nullable<T>) UNDEFINED;
return t;
}
public static <T> Nullable<T> of(T value) {
return new Nullable<T>(value, true);
}
public T get() {
if (!isPresent) {
throw new NoSuchElementException("Value is undefined");
}
return value;
}
public boolean isPresent() {
return isPresent;
}
}