Question

我有以下结构：

public class Customer
{
  public int ID { get; set; }
  public List<Order> Orders { get; set; }
}

public class Order
{
  public int ID { get; set; }
  public int ProductID { get set; }
}

我需要获得订购ProductID = 6的客户的集合。流畅的样式LINQ会是什么样的？

我试着在下面没有运气：

var customers = allCustomers.SelectMany(c => c.Orders.Select(o => o.ProductID.Equals(6))).ToArray();

Answer 1

var customers = allCustomers.Where(c => c.Orders.Any(o => o.ProductID == 6));

Answer 2

allCustomers.Where(c => c.Orders.Any(o => o.ProductID == 6))

Answer 3

var customers = allCustomers.Where(c => c.Orders.Any(o => o.ProductID == 6));

Answer 4

看起来你想要：

var query = allCustomers.Where(c => c.Orders.Any(o => o.ProductID == 6));

Answer 5

一个很好的方法就是从另一边尝试这样的

var customers from p in Order where p.ProductId == 6 select p.Customer

当然，您需要在Order类中添加Customer属性，如此

public class Order
{
  public int ID { get; set; }
  public int ProductID { get set; }
  public Customer Customer { get; set; }
}

LINQ：查询集合中的集合

5 个答案: