public async Task <int> CreateAsync(FpReturnFromBuyerModel model)
        {
            do
            {
                model.Code = CodeGenerator.GenerateCode();
            }while (_dbSet.Any(d => d.Code.Equals(model.Code)));

            model.FlagForCreate(_identityService.Username, UserAgent);
            foreach (var detail in model.Details)
            {
                detail.FlagForCreate(_identityService.Username, UserAgent);
                foreach (var item in detail.Items)
                {
                    item.FlagForCreate(_identityService.Username, UserAgent);
                    _dbItemSet.Add(item);
                }
                _dbDetailSet.Add(detail);
            }
            _dbSet.Add(model);

            await CreateInventory(model, "IN");

            return(await _dbContext.SaveChangesAsync());
        }