如何拆分Linq函數？

Question

我有一個LINQ-功能，partialy獲取不同的方法使用，所以我認爲這將有可能以不同的部分，我會打電話，當我需要他們分裂：

public static void SetTab(int tab) 
    { 
     var collection = from product in Entity.Collection.collection 
         let p = product as Entity.Base.Product 
         from version in p.version 
         let v = version as Entity.Base.Version 
         from customer in v.customerCollection 
         let c = customer as Entity.Base.Customer 
         from error in v.errorCollection 
         let e = error as Entity.Base.Error 
         select new { p, v, c, e }; 

     Entity.Selection.products = (List<Entity.Base.Product>)collection.Select(x => x.p).Distinct().ToList(); 
      Entity.Selection.versions = (List<Entity.Base.Version>)collection.Select(x => x.v).Distinct().ToList(); 
       Entity.Selection.customers = (List<Entity.Base.Customer>)collection.Select(x => x.c).Distinct().ToList(); 
       Entity.Selection.errors = (List<Entity.Base.Error>)collection.Select(x => x.e).Distinct().ToList(); 
        Entity.Selection.categories = (List<Entity.Base.Category>)collection.Select(x => x.e.category).Distinct().ToList(); 

     switch (tab) 
     { 
      case 0: 
       Entity.DataSource.MainTab.lbProduct = Converter.ListConverter.ToBindingList(Entity.Selection.products); 
        Entity.DataSource.MainTab.lbVersion = Converter.ListConverter.ToBindingList(Entity.Selection.versions); 
         Entity.DataSource.MainTab.lbCustomer = Converter.ListConverter.ToBindingList(Entity.Selection.customers); 
         Entity.DataSource.MainTab.lbError = Converter.ListConverter.ToBindingList(Entity.Selection.errors); 
          Entity.DataSource.MainTab.lbCategory = Converter.ListConverter.CategoryToBindingList(Entity.Selection.categories); 
       break; 
     } 
    } 

這應該是這個樣子：

private static object GetFrom() 
    { 
     var collection = from product in Entity.Collection.collection 
         let p = product as Entity.Base.Product 
         from version in p.version 
         let v = version as Entity.Base.Version 
         from customer in v.customerCollection 
         let c = customer as Entity.Base.Customer 
         from error in v.errorCollection 
         let e = error as Entity.Base.Error 
         select new { p, v, c, e }; 
    } 

    public static void SetTab(int tab) 
    { 
     Reduce(GetFrom()); 
     SelectThis(0); 
    } 

    private static void Reduce(object collection) 
    { 
     Entity.Selection.products = (List<Entity.Base.Product>)collection.Select(x => x.p).Distinct().ToList(); 
      Entity.Selection.versions = (List<Entity.Base.Version>)collection.Select(x => x.v).Distinct().ToList(); 
       Entity.Selection.customers = (List<Entity.Base.Customer>)collection.Select(x => x.c).Distinct().ToList(); 
       Entity.Selection.errors = (List<Entity.Base.Error>)collection.Select(x => x.e).Distinct().ToList(); 
        Entity.Selection.categories = (List<Entity.Base.Category>)collection.Select(x => x.e.category).Distinct().ToList(); 
    } 

    private static void SelectThis(int i) 
    { 
     switch (tab) 
     { 
      case 0: 
       Entity.DataSource.MainTab.lbProduct = Converter.ListConverter.ToBindingList(Entity.Selection.products); 
        Entity.DataSource.MainTab.lbVersion = Converter.ListConverter.ToBindingList(Entity.Selection.versions); 
         Entity.DataSource.MainTab.lbCustomer = Converter.ListConverter.ToBindingList(Entity.Selection.customers); 
         Entity.DataSource.MainTab.lbError = Converter.ListConverter.ToBindingList(Entity.Selection.errors); 
          Entity.DataSource.MainTab.lbCategory = Converter.ListConverter.CategoryToBindingList(Entity.Selection.categories); 
       break; 
     } 
    } 

我的問題是：我需要什麼來使用，而不是「對象」從一個方法傳遞「變種集合」到另一個？

Answer 1

您需要定義一個顯式類，它等同於現在定義的匿名類作爲查詢的一部分。 和我強烈建議您在查詢上調用ToList()，因爲這可以確保查詢只執行一次。

public class MyClass 
{ 
    Entity.Base.Product Product { get; private set; } 
    Entity.Base.Version Version { get; private set; } 
    Entity.Base.Customer Customer { get; private set; } 
    Entity.Base.Error Error { get; private set; } 

    public MyClass(
       Entity.Base.Product product, 
       Entity.Base.Version version, 
       Entity.Base.Customer customer, 
       Entity.Base.Error error) 
    { 
     this.Product = product; 
     this.Version = version; 
     this.Customer = customer; 
     this.Error = error; 
    } 
} 

然後，你可以寫：

private static List<MyClass> GetFrom() 
{ 
    return (from product in Entity.Collection.collection 
      let p = product as Entity.Base.Product 
      from version in p.version 
      let v = version as Entity.Base.Version 
      from customer in v.customerCollection 
      let c = customer as Entity.Base.Customer 
      from error in v.errorCollection 
      let e = error as Entity.Base.Error 
      select new MyClass(p, v, c, e) 
      ).ToList(); 
}