Linq to Entities Group Sum计算的属性

Question

使用C＃4和EF5。

有麻烦，试图总结计算特性：

The specified type member 'QtyAvailable' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported. 

下面是属性定义：

public decimal QtyAvailable 
    { 
     get 
     { return this.QtyInContainer - this.QtyAllocated; } 
    } 

这里是LINQ的：

var viewModel = 
       companyItems 
         .GroupJoin(
          inventory, 
          items => items.Id, 
          inven => inven.ItemId, (im, icd) => new { im, icd } 
          ) 
         .SelectMany(
          itemInven => itemInven.icd.DefaultIfEmpty(), 
          (im, icd) => new { im, icd } 
         ) 
         .GroupBy(g => new 
          { 
           g.im.im.Id 
          } 
         ) 
         .Select(group => 
           new ItemAvailabilityViewModel() 
           { 
            Id = group.Key.Id, 
            QtyAvailable = group.Sum(jt => jt.icd == null ? 0 : jt.icd.QtyAvailable), 
            UnitCashPrice = group.Max(jt => jt.im.im.UnitSellPrice), 
            UnitCreditPrice = group.Max(jt => jt.im.im.UnitSellPrice * (1 + company.CashDiscountPct)), 
            CustomerUnitPrice = group.Max(jt => jt.im.im.UnitSellPrice * (1 + decCreditPriceMarkup)) 
           } 
         ) 
         ; 

不知道如何实现这个结果。我需要以某种方式将其分解为2个查询吗？

Answer 1

看起来像把这个分解成2个查询就是票。从我猜想发生的事情来看，第一次，当你调用.ToList（）时，它解析了计算的属性，使得它本质上不再为第二个查询计算然后求和。这里是结果代码：

//join of Recpt Header and Detail 
      var unGroupedJoin = 
       companyItems 
         .GroupJoin(
          inventory, 
          items => items.Id, 
          inven => inven.ItemId, (im, icd) => new { im, icd } 
          ) 
         .SelectMany(
          itemInven => itemInven.icd.DefaultIfEmpty(), 
          (im, icd) => new { im, icd } 
         ).ToList(); 

      var viewModel = 
       unGroupedJoin 
         .GroupBy(g => new 
          { 
           g.im.im.Id 
          } 
         ) 
         .Select(group => 
           new ItemAvailabilityViewModel() 
           { 
            Id = group.Key.Id, 
            QtyAvailable = group.Sum(jt => jt.icd == null ? 0 : jt.icd.QtyAvailable), 
            UnitCashPrice = group.Max(jt => jt.im.im.UnitSellPrice), 
            UnitCreditPrice = group.Max(jt => jt.im.im.UnitSellPrice * (1 + company.CashDiscountPct)), 
            CustomerUnitPrice = group.Max(jt => jt.im.im.UnitSellPrice * (1 + decCreditPriceMarkup)) 
           } 
         ).ToList() 
         ;