Map Domain to GQL Types with Convertors

Convertor-Based Type Mapping

Use Convertors for all transformations between domain types and GQL types.

Map Domain to GQL Types with Convertors

GQL Raw -> Domain Model (Model Convertor)

@riverpod
Convertor<AttendeeModel, GQueryAttendeeData_attendee_attendeeItems>
attendeeModelConvertor(Ref ref) {
  return Convertor((raw) {
    return AttendeeModel(
      id: raw.id ?? '',
      fullName: raw.fullName ?? 'Unknown',
      email: raw.email ?? '',
      jobTitle: raw.jobTitle ?? '',
      createdAt: raw.createdAt ?? DateTime.now(),
    );
  });
}

Domain Filter -> GQL Filter (Filter Convertor)

@riverpod
Convertor<GattendeeFilters, AttendeeFilterCriteria>
attendeeFilterConvertor(Ref ref) {
  return Convertor((filter) {
    return GattendeeFilters((b) => b
      ..id = filter.id
      ..fullName = filter.fullName != null
          ? GStringFiltersBuilder().construct(contains: filter.fullName)
          : null);
  });
}

Domain Sort -> GQL Sort (Sort Convertor)

@riverpod
Convertor<GattendeeOrder, AttendeeSortCriteria>
attendeeSortConvertor(Ref ref) {
  return Convertor((sort) {
    return GattendeeOrder((b) => b
      ..fullName = sort.fullName?.value
      ..createdAt = sort.createdAt?.value);
  });
}

Domain Input -> GQL Mutation Vars (Input Convertor)

@riverpod
Convertor<GMutateAttendeeSaveVars, AttendeeUpsertInput>
attendeeInputConvertor(Ref ref) {
  return Convertor((input) {
    return GMutateAttendeeSaveVars((b) => b
      ..attendeeArg.replace(GAttendeeArgs((args) => args
        ..fullName = input.fullName
        ..email = input.email
        ..jobTitle = input.jobTitle)));
  });
}

Usage with mightExecute

For nullable parameters, use mightExecute which handles null input gracefully:

final params = ListRequestParams<GattendeeFilters, GattendeeOrder>(
  filter: filterConvertor.mightExecute(filter), // returns null if filter is null
  sort: sortConvertor.mightExecute(sort),
);

Why Convertors Instead of Extensions?

Concern	Manual Extensions	Convertors
Forgotten fields	Discovered at runtime	Explicit in Convertor function
Testability	Hard to test in isolation	Pure function, easy to unit test
Composability	No composition	Chain with .then(), .thenMap()
Null safety	Manual ?? handling	Centralized in one place