与ViewModel的IQueryable Union不起作用

Question

I have two queries that return the same IQueryable viewmodel.

This is my first query:

var tempAfter = (from operation in _br_WarehouseOperation_GetAll.GetAll()
                 select new CardexSummaryViewModel
                         {
                             SumFirstImport = 0,
                             SumFirstExport = 0,
                             SumExport = g.Where(t => exportTypes == t.operation.TransactionTypeId).Sum(t => t.operationDetail.Quantity * t.operationDetail.UnitOfMeasure.ConversionFactor),
                             SumImport = g.Where(t => importTypes.Contains(t.operation.TransactionTypeId)).Sum(t => t.operationDetail.Quantity * t.operationDetail.UnitOfMeasure.ConversionFactor),
                             WarehouseGoodsId = warehouseGoods.WarehouseGoodsId,
                             SumPriceFirstImport = 0,
                             SumPriceFirstExport = 0,
                             SumPriceExport = g.Where(t => isPricing && exportTypes == t.operation.TransactionTypeId).Sum(t => t.operationDetail.WarehouseTransactionOperationPricings.Sum(it => it.TotalPrice)),
                             SumPriceImport = g.Where(t => isPricing && importTypes.Contains(t.operation.TransactionTypeId)).Sum(t => t.operationDetail.WarehouseTransactionOperationPricings.Sum(it => it.TotalPrice)),
                         });

and this is second query :

var tempBefore = (from operation in _br_WarehouseOperation_GetAll.GetAll()
                  select new CardexSummaryViewModel
                              {
                                  SumFirstImport = g.Where(t => importTypes.Contains(t.operation.TransactionTypeId)).Sum(t => t.operationDetail.Quantity * t.operationDetail.UnitOfMeasure.ConversionFactor),
                                  SumFirstExport = g.Where(t => exportTypes == t.operation.TransactionTypeId).Sum(t => t.operationDetail.Quantity * t.operationDetail.UnitOfMeasure.ConversionFactor),
                                  SumExport = 0,
                                  SumImport = 0,
                                  WarehouseGoodsId = warehouseGoods.WarehouseGoodsId,

                                  SumPriceFirstImport = g.Where(t => isPricing && importTypes.Contains(t.operation.TransactionTypeId))
                                            .Sum(t => t.operationDetail.WarehouseTransactionOperationPricings.Sum(it => it.TotalPrice)),
                                  SumPriceFirstExport = g.Where(t => isPricing && exportTypes == t.operation.TransactionTypeId)
                                            .Sum(t => t.operationDetail.WarehouseTransactionOperationPricings.Sum(it => it.TotalPrice)),
                                  SumPriceExport = 0,
                                  SumPriceImport = 0,
                              });

I want to union these two queries into one database call like this :

 tempAfter = tempBefore.Union(tempAfter);
 cardexSummery = tempAfter.ToList();

but it does not work and duplicates the rows.

I was wondering if anybody could tell me where I am missing something. Thanks

Answer 1

Both linq statements are creating new CardexSummaryViewModel instances. Since hey are distinct instances the Union statement is doing it's job. You would need to provide all the equality checks/overrides in this class to determine if the instances are actually equal. Then the Union would filter out duplicates. It would still be possible to have two instances from one of the linq statements be equal, in which case, the Union would not filter those out, only equal objects from the two different statements. So, you would still want to use Distinct() after Union if you want all duplicates removed.