簡化我的Linq查詢和工會

Question

我有以下Linq查詢，其中我從兩個不同的表中檢索具有相同過濾器和連接的數據;最後結合結果集。

  var plannedReceiptsResult = db.OMS_Planned_Receipts.Where(p => p.Product == product && p.PeriodID >= StartPeriod && p.PeriodID <= EndPeriod) 
      .Join(db.Periods, c => c.PeriodID, o => o.PeriodID, (c, o) => new { c, o }) 
      .Select(b => new PivotViewModel 
      { 
       Product = b.c.Product, 
       PeriodID = b.c.PeriodID, 
       SiteID = b.c.SiteID, 
       Value = b.c.Value, 
       Activity = "Planned Receipts", 
       PeriodStart = b.o.Period_Start, 
       PeriodEnd = b.o.Period_End, 
       PeriodDescription = b.o.Display 
      }); 

     var systemForecastResult = db.OMS_System_Forecast.Where(p => p.Product == product && p.PeriodID >= StartPeriod && p.PeriodID <= EndPeriod) 
       .Join(db.Periods, c => c.PeriodID, o => o.PeriodID, (c, o) => new { c, o }) 
      .Select(b => new PivotViewModel 
      { 
       Product = b.c.Product, 
       PeriodID = b.c.PeriodID, 
       SiteID = b.c.SiteID, 
       Value = b.c.Value, 
       Activity = "System Forecast", 
       PeriodStart = b.o.Period_Start, 
       PeriodEnd = b.o.Period_End, 
       PeriodDescription = b.o.Display 
      }); 

     var activityResult = plannedReceiptsResult.Union(systemForecastResult); 

我需要對另外8個表執行相同的操作，最後將它們的結果集合在一起。我所有的表都有相同的模式。我希望用一個委託或方法來簡化它。請指教。

同時請注意，我使用EF 5 IDBSet過濾按applying global filters article

---

我覺得下面的方法應該是，但我不知道我應該如何調用它。

public interface IEntity 
{ 
    Int16 TenantID { get; set; } 
    string Product { get; set; } 
    string SiteID { get; set; } 
    int PeriodID { get; set; } 
    double? Value { get; set; } 
} 

     public static void UnionActivity<T>(IDbSet<T> source, IQueryable<DAL.Period> jointSource, 
    string product, string activity, int StartPeriod, double EndPeriod, ref List<PivotViewModel> unionSet) where T : class, IEntity 
    { 

     unionSet = unionSet.Union(source.Where(p => p.Product == product && p.PeriodID >= StartPeriod && p.PeriodID <= EndPeriod) 
      .Join(jointSource, c => c.PeriodID, o => o.PeriodID, (c, o) => new { c, o }) 
      .Select(b => new PivotViewModel 
      { 
       Product = b.c.Product, 
       PeriodID = b.c.PeriodID, 
       SiteID = b.c.SiteID, 
       Value = b.c.Value, 
       Activity = activity, 
       PeriodStart = b.o.Period_Start, 
       PeriodEnd = b.o.Period_End, 
       PeriodDescription = b.o.Display 
      })).ToList(); 
    } 

我嘗試以下，但有語法錯誤：

 List<PivotViewModel> activityResult1 = new List<PivotViewModel>(); 
     ViewerModel.UnionActivity<System.Data.Entity.IDbSet<DAL.OMS_Planned_Receipts)>(db.OMS_Planned_Receipts, db.Periods, product, "Planned Receipts", StartPeriod, iEndPeriod, ref activityResult1); 

Answer 1

下面的例子應該爲你工作。

public void Load() 
{ 

    List<PivotViewModel> activityResult = new List<PivotViewModel>(); 
    MyLinq(db.OMS_Planned_Receipts, db.Periods, "System ForeCast", ref activityResult); 
    MyLinq(db.OMS_System_Forecast, db.Periods, "System ForeCast", activityResult); 

    //activityResult has unionized result   
} 

private void MyLinq(IEnumerable<MyData> myData, IEnumerable<MyPeriod> periods, string activity, ref IEnumerable<PivotViewModel> unionSet) 
{ 
    unionSet = unionSet.Union 
    (
     myData.Where(p => p.Product == product && p.PeriodID >= StartPeriod && p.PeriodID <= EndPeriod) 
     .Join(periods, c => c.PeriodID, o => o.PeriodID, (c, o) => new { c, o }) 
     .Select(b => new PivotViewModel 
     { 
      Product = b.c.Product, 
      PeriodID = b.c.PeriodID, 
      SiteID = b.c.SiteID, 
      Value = b.c.Value, 
      Activity = activity, 
      PeriodStart = b.o.Period_Start, 
      PeriodEnd = b.o.Period_End, 
      PeriodDescription = b.o.Display 
     }) 
    ).ToList(); 
} 

Answer 2

我不知道這是否是好的，但因爲你所有的實體類具有相同的屬性，我們可以創建一個接口，使實體類使用部分類實現它。有了這個接口，我們可以創建一個從IQueryable中提取數據的方法。

就是這樣。

public interface IEntity 
{ 
    string Product { get; set; } 
    int PeriodID { get; set; } 
    object SiteID { get; set; } 
    object Value { get; set; } 
} 

public partial class OMS_Planned_Receipt : IEntity // Don't know the exact name of your entity class 
{ 
} 

public partial class OMS_System_Forecast : IEntity 
{ 
} 

private static IQueryable<PivotViewModel> SelectObjects(IQueryable<IEntity> source,IQueryable<PeriodEntity> jointSource, string product, int StartPeriod, int EndPeriod) 
    { 
     return source.Where(p => p.Product == product && p.PeriodID >= StartPeriod && p.PeriodID <= EndPeriod) 
      .Join(jointSource, c => c.PeriodID, o => o.PeriodID, (c, o) => new { c, o }) 
      .Select(b => new PivotViewModel 
     { 
      Product = b.c.Product, 
      PeriodID = b.c.PeriodID, 
      SiteID = b.c.SiteID, 
      Value = b.c.Value, 
      Activity = "System Forecast", 
      PeriodStart = b.o.Period_Start, 
      PeriodEnd = b.o.Period_End, 
      PeriodDescription = b.o.Display 
     }); 
    } 

因此，你可以調用這個方法就像

var receipts = SelectObjects(db.OMS_Planned_Receipts, db.Periods, product, StartPeriod, EndPeriod); 
var forecasts = SelectObjects(db.OMS_System_Forecast, db.Periods, product, StartPeriod, EndPeriod);