public async Task <ServiceResult <int> > GetList(ClaimsPrincipal user, int groupId) { var group = groupsRepository.Get(groupId); if (group is null) { return(ServiceResult <int> .Error(404, "Group was not found")); } var authorizationResult = await authorizationService.AuthorizeAsync(user, group, GroupOperations.Read); if (!authorizationResult.Succeeded) { return(ServiceResult <int> .Error(401, "Unauthorized")); } var result = await transactionsRepository.GetList(groupId); if (result is null) { return(ServiceResult <int> .Error(404, "No transactions were found")); } return(ServiceResult <int> .Success(result.Select(TransactionViewModel.FromModel))); }