幫助與LINQ投影

Question

我有一個ICollection<Product>：

var products = productRepository.FindAll();

Product有一個名爲Orders屬性，它是一個ICollection<Order>。

我試圖最後得到ICollection<Order>，對於給定的CustomerId。

換句話說：

鑑於產品的集合，我想要檢索訂單列表特定客戶

這是我有：

var orders = products 
       .Where(x => x.Orders != null) 
       .Where(x => x.Orders.Any(y => y.CustomerId == 10)) 
       .Select(x => x.Orders) 
       .ToList(); 

但我最終以List<ICollection<Order>>，我想要一個ICollection<Order>。我需要做某種分組嗎？

Answer 1

關於什麼：

var orders = products 
      .Where(x => x.Orders != null) 
      .Where(x => x.Orders.Any(y => y.CustomerId == 10)) 
      .SelectMany(x => x.Orders) 
      .ToList(); 

Answer 2

如果你想訂單單一產品的集合，然後這會工作

var orders = products 
       .Where(x => x.Orders != null) 
       .Where(x => x.Orders.Any(y => y.CustomerId == 10)) 
       .Select(x => x.Orders) 
       .Single();