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映射列表未从主列表获取所有项

collections linq c#

David B · 技术社区 · 7 年前

我出口了3.2万件产品,但有一个奇怪的问题,重新列出的只有1917件,我不知道为什么是这样。

 private List<FTradeItemsExport> MapTradeItems(List<TradeItems> tradeItem)
    {
        List<TradeItemsExport> retList = new List<TradeItemsExport>();
        try
            {

                var StockImport = new Fuel_StockItemImports();


                List<StandardLookUpList> _AnalsisCodes = GetAnayalsisCodesForExportCode();

                StandardLookUpList sport = new StandardLookUpList();
                StandardLookUpList gender = new StandardLookUpList();
                StandardLookUpList colour = new StandardLookUpList();
                StandardLookUpList Size = new StandardLookUpList();
                StandardLookUpList categorycode = new StandardLookUpList();
                StandardLookUpList categorydesc = new StandardLookUpList();
                StandardLookUpList subcategorycode = new StandardLookUpList();
                StandardLookUpList subcategorydesc = new StandardLookUpList();

                StandardLookUpList brandcode = new StandardLookUpList();
                StandardLookUpList branddesc = new StandardLookUpList();


                foreach (var item in tradeItem)
                {

                    var codesForThisItem = _AnalsisCodes.Where(w => w.ItemCode == item.ItemCode);
                    if (codesForThisItem.Any())
                    {
                        sport = codesForThisItem.FirstOrDefault(x => x.code == Constants.Sport);

                        gender = codesForThisItem.FirstOrDefault(x => x.code == Constants.Gender);
                        colour = codesForThisItem.FirstOrDefault(x => x.code == Constants.Colour);
                        Size = codesForThisItem.FirstOrDefault(x => x.code == Constants.Size);
                        categorycode = codesForThisItem.FirstOrDefault(x => x.code == Constants.Colour);
                        categorydesc = codesForThisItem.FirstOrDefault(x => x.code == Constants.Category);

                        subcategorycode = codesForThisItem.FirstOrDefault(x => x.code == Constants.Category);
                        subcategorydesc = codesForThisItem.FirstOrDefault(x => x.code == Constants.SubCategory);
                        brandcode = codesForThisItem.FirstOrDefault(x => x.code == Constants.Brand);
                    }
                    retList.Add(new  TradeItemsExport()
                    {
                        ItemCode = item.ItemCode,
                        BarCode = item.BarCode,
                        Description = item.Description,
                        SupplierCode = item.SupplierCode,
                        SupplierStockCode = item.SupplierStockCode,
                        Product_Group_Code = "",
                        Product_Group_Desc = "",
                        SportCode = sport.LookupValue.ToStringOrEmpty(),
                        SportDesc = sport.description.ToStringOrEmpty(),
                        GenderCode = gender.LookupValue.ToStringOrEmpty(),
                        GenderDesc = gender.description.ToStringOrEmpty(),
                        ColourCode = colour.LookupValue.ToStringOrEmpty(),
                        ColourDesc = colour.description.ToStringOrEmpty(),
                        SizeCode = Size.LookupValue.ToStringOrEmpty(),
                        SizeDesc = Size.description.ToStringOrEmpty(),
                        CategoryCode = categorycode.LookupValue.ToStringOrEmpty(),
                        CategoryDesc = categorydesc.description.ToStringOrEmpty(),
                        subcategorycode = subcategorycode.LookupValue.ToStringOrEmpty(),
                        subcategorydesc = subcategorydesc.description.ToStringOrEmpty(),
                        BrandsCode = brandcode.LookupValue.ToStringOrEmpty(),
                        BrandsDesc = branddesc.description.ToStringOrEmpty(),
                        Vat = item.Vat,
                        GrossWeight = item.Weight,
                        CommodityCode = item.CommodityCode,
                        price_exVAT = item.price_exVAT,
                        price_incVAT = item.price_incVAT,
                        currentprice_exVAT = item.currentprice_exVAT,
                        currentprice_incVAT = item.currentprice_incVAT,
                        creation_date = item.creation_date,
                        Inactive_date = item.Inactive_date,
                        status = 1



                    });
                    var Stock = new Fuel_StockItemImport();



                    Stock.StockItem = item.ItemCode;
                    Stock.IsProcessed = true;
                    Stock.DateImported = DateTime.Now;
                    StockImport.Add(Stock);
                    StockImport.Update();


                }


            }
            catch (Exception ex)
            {

            }
            return retList;


    }

如您所见,下面是映射列表中预期的项目的真实数字,我不明白,因为我没有得到任何数据异常?。当我检查代码并检查刹车点时,它不会在任何引用为空的地方爆炸,所以不确定发生了什么。

1 回复 | 直到 7 年前

Sergey Kalinichenko 7 年前

这可能发生的唯一方法是,在插入1912个项目之后,忽略循环中间的异常。

最可能的原因是 ToStringOrEmpty() 施工时 TradeItemsExport 物体。你可以用 ?. 操作员。

一般来说,不应忽略所有异常。 catch (Exception ex) { } 那没用。如果不知道如何处理异常,就不应该有捕获它的代码。在这种情况下,它显然是一个编程问题(无法对对象进行null检查)。 try / catch 应该全部移除。

(摘自评论) 有没有一种更快的合并方法?

你可以通过更换 Where(w => w.ItemCode == item.ItemCode) 在字典中使用基于哈希的查找:

var byItemCode = _AnalsisCodes
    .GroupBy(w => w.ItemCode)
    .ToDictionary(g => g.Key, g => g.First());
...
foreach (var item in tradeItem) {
    if (byItemCode.TryGetValue(item.ItemCode, out var codesForThisItem) && codesForThisItem.Any()) {
        ...
    }
}

如果这并不能加快足够的速度,那么你需要重新组织内部的查找。 codesForThisItem 在进入循环之前设置字典。