为什么这个 Linq 左外连接不能按预期工作？

Question

我有两个列表，都使用相同的类（部分）。第一个列表是“主”列表 (engineerParts)，第二个列表 (partDefaults) 是这些部件的属性值列表。

第一个列表包含 263 个项目，第二个列表包含 238 个项目。因此，最终列表应该包含 263 个项目。然而事实并非如此，它包含 598 个！

var partsWithDefaults = from a in engineerParts
                                    join b in partDefaults on
                                    new { a.PartNumber, a.Revision }
                                    equals
                                    new { b.PartNumber, b.Revision } into j1
                                    from j2 in j1.DefaultIfEmpty()
                                    select new Part()
                                    {
                                        NewPart = isNewPart(a.PartNumber, PadRevision(a.Revision), concatenateRevision),
                                        PartNumber = concatenateRevision == true ? string.Concat(a.PartNumber, PadRevision(a.Revision)) : a.PartNumber,
                                        Revision = concatenateRevision == true ? "" : a.Revision,
                                        ParentPart = a.ParentPart,
                                        Description = a.Description,
                                        BoMQty = a.BoMQty,
                                        UoM = (j2 != null) ? j2.UoM : null,
                                        ClassId = (j2 != null) ? j2.ClassId : null,
                                        ShortDescription = (j2 != null) ? j2.ShortDescription : null,
                                        ABCCode = (j2 != null) ? j2.ABCCode : null,
                                        BuyerId = (j2 != null) ? j2.BuyerId : null,
                                        PlannerId = (j2 != null) ? j2.PlannerId : null,
                                        OrderPolicy = (j2 != null) ? j2.OrderPolicy : null,
                                        FixedOrderQty = (j2 != null) ? j2.FixedOrderQty : null,
                                        OrderPointQty = (j2 != null) ? j2.OrderPointQty : null,
                                        OrderUpToLevel = (j2 != null) ? j2.OrderUpToLevel : null,
                                        OrderQtyMin = (j2 != null) ? j2.OrderQtyMin : null,
                                        OrderQtyMax = (j2 != null) ? j2.OrderQtyMax : null,
                                        OrderQtyMultiple = (j2 != null) ? j2.OrderQtyMultiple : null,
                                        ReplenishmentMethod = (j2 != null) ? j2.ReplenishmentMethod : null,
                                        ItemShrinkageFactor = (j2 != null) ? j2.ItemShrinkageFactor : null,
                                        PurchasingLeadTime = (j2 != null) ? j2.PurchasingLeadTime : null,
                                        MFGFixedLeadTime = (j2 != null) ? j2.MFGFixedLeadTime : null,
                                        PlanningTimeFence = (j2 != null) ? j2.PlanningTimeFence : null,
                                        FulfillMethod = (j2 != null) ? j2.FulfillMethod : null,
                                        ItemStatus = (j2 != null) ? j2.ItemStatus : null,
                                        TreatAsEither = (j2 != null) ? j2.TreatAsEither : false,
                                        AltItem1 = (j2 != null) ? j2.AltItem1 : null,
                                        AltItem2 = (j2 != null) ? j2.AltItem2 : null,
                                        AltItem3 = (j2 != null) ? j2.AltItem3 : null,
                                        AltItem4 = (j2 != null) ? j2.AltItem4 : null,
                                        AltItem5 = (j2 != null) ? j2.AltItem5 : null,
                                        DesignAuthority = (j2 != null) ? j2.DesignAuthority : null,
                                        Level = a.Level
                                    };

            return partsWithDefaults.ToList<Part>();

Answer 1

原来是数据问题。向我发送第二个列表的 Excel 数据的人在其中留下了重复项！！！！