Wie drei Klassen in LINQ C# verbinden

Question

Hallo kann mir sagen, wie LINQ-Syntax mit Klassen zu erstellen:

// Client: int ID, string Name 
// Item:  int ID, float Price 
// Purchase: int ClientID, int ItemID 

Namen von Kunden zu bekommen, die mehr als 100 (Summe ihrer Einzelteilpreis) ausgegeben

static List<Client> GetClients() 
    { 
     return new List<Client> 
     { 
      new Client {Id=1, Name="Jon" }, 
      new Client {Id=2, Name="Ben" }, 
      new Client {Id=3, Name="Tom" }, 
      new Client {Id=4, Name="Sara" }, 
     }; 
    } 

    static List<Item> GetItems() 
    { 
     return new List<Item> 
     { 
      new Item {Id=1, Price = 8f }, 
      new Item {Id=2, Price = 8f }, 
      new Item {Id=3, Price = 75f }, 
      new Item {Id=4, Price = 33.33f }, 
      new Item {Id=5, Price = 82.5f }, 
      new Item {Id=6, Price = 25f }, 
     }; 
    } 

    static List<Purchase> GetPurchases() 
    { 
     return new List<Purchase> 
     { 
      new Purchase(1,1), 
      new Purchase(1,2), 
      new Purchase(2,3), 
      new Purchase(2,3), 
      new Purchase(2,3), 
      new Purchase(3,5), 
      new Purchase(3,6), 
      new Purchase(4,2), 
      new Purchase(4,2), 
      new Purchase(5,3), 
      new Purchase(5,3), 
      new Purchase(5,3), 
      new Purchase(6,4), 
      new Purchase(6,1) 
     }; 
    } 

    static void Main(string[] args) 
    { 

     var clients = GetClients(); 
     var items = GetItems(); 
     var purchases = GetPurchases(); 

     // need LINQ here 
    } 

Answer 1

Versuchen Sie, diese

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 

namespace ConsoleApplication1 
{ 
    class Program 
    { 
     static List<Client> GetClients() 
     { 
      return new List<Client> 
     { 
      new Client {Id=1, Name="Jon" }, 
      new Client {Id=2, Name="Ben" }, 
      new Client {Id=3, Name="Tom" }, 
      new Client {Id=4, Name="Sara" }, 
     }; 
     } 

     static List<Item> GetItems() 
     { 
      return new List<Item> 
     { 
      new Item {Id=1, Price = 8f }, 
      new Item {Id=2, Price = 8f }, 
      new Item {Id=3, Price = 75f }, 
      new Item {Id=4, Price = 33.33f }, 
      new Item {Id=5, Price = 82.5f }, 
      new Item {Id=6, Price = 25f }, 
     }; 
     } 

     static List<Purchase> GetPurchases() 
     { 
      return new List<Purchase> 
     { 
      new Purchase(1,1), 
      new Purchase(1,2), 
      new Purchase(2,3), 
      new Purchase(2,3), 
      new Purchase(2,3), 
      new Purchase(3,5), 
      new Purchase(3,6), 
      new Purchase(4,2), 
      new Purchase(4,2), 
      new Purchase(5,3), 
      new Purchase(5,3), 
      new Purchase(5,3), 
      new Purchase(6,4), 
      new Purchase(6,1) 
     }; 
     } 
     static void Main(string[] args) 
     { 
      List<Client> clients = GetClients(); 
      List<Item> items = GetItems(); 
      List<Purchase> purchases = GetPurchases(); 

      var results = (from p in purchases 
          join c in clients on p.ClientID equals c.Id 
          join i in items on p.ItemID equals i.Id 
          select new { purchase = p, client = c, item = i }) 
          .GroupBy(x => x.client) 
          .Where(x => x.Sum(y => y.item.Price) > 100) 
          .Select(x => x.FirstOrDefault().client.Name) 
          .ToList(); 
     } 
    } 
    public class Client 
    { 
     public int Id { get; set; } 
     public string Name { get; set; } 

    } 

    public class Item 
    { 
     public int Id { get; set; } 
     public float Price { get; set; } 
    } 

    public class Purchase 
    { 
     public int ClientID { get; set; } 
     public int ItemID { get; set; } 

     public Purchase(int item, int client) 
     { 
      ItemID = item; 
      ClientID = client; 
     } 
    } 
}