public IQueryable <SpellViewModel> GetAll(int?filter = null)
{
var query = _spellRepository.Select().ProjectTo <SpellViewModel>(MapperConfig)
.OrderBy(x => x.MagicSchoolId).ThenBy(x => x.Level).AsQueryable();
return(filter is null ? query : query.Where(x => x.MagicSchoolId == filter));
}