Question

我需要返回所有具有有效联系方式的客户：

联系方式：

public class Contact
{
    public int ID { get; set; }
    public string Name { get; set; }
    public bool IsValid { get; set; }
}

客户类别：

public class Customer
{
    public int ID { get; set; }
    public string Name { get; set; }
    public List<Contact> Contacts { get; set; }
}

客户列表：

List<Customer> customers = new List<Customer>
{
   new Customer
   {
       ID = 1,
       Name = "Ahmed",
       Contacts = new List<Contact>
       {
           new Contact { ID = 1 , Name = "A", IsValid = true },
           new Contact { ID = 2 , Name = "B", IsValid = true },
           new Contact { ID = 3 , Name = "C", IsValid = true }
       }
   },
   new Customer
   {
       ID = 2,
       Name = "Mohamed",
       Contacts = new List<Contact>
       {
           new Contact { ID = 4 , Name = "D", IsValid = true },
           new Contact { ID = 5 , Name = "E", IsValid = true },
           new Contact { ID = 6 , Name = "F", IsValid = false }
       }
   },
   new Customer
   {
       ID = 3,
       Name = "Ali",
       Contacts = new List<Contact>
       {
           new Contact { ID = 7 , Name = "X", IsValid = false },
           new Contact { ID = 8 , Name = "Y", IsValid = false },
           new Contact { ID = 9 , Name = "Z", IsValid = false }
       }
   }
};

应用LINQ后需要结果：

List<Customer> customersResult = new List<Customer>
            {
                new Customer
                {
                    ID = 1,
                    Name = "Ahmed",
                    Contacts = new List<Contact>
                    {
                        new Contact { ID = 1 , Name = "A", IsValid = true },
                        new Contact { ID = 2 , Name = "B", IsValid = true },
                        new Contact { ID = 3 , Name = "C", IsValid = true }
                    }
                },
                new Customer
                {
                    ID = 2,
                    Name = "Mohamed",
                    Contacts = new List<Contact>
                    {
                        new Contact { ID = 4 , Name = "D", IsValid = true },
                        new Contact { ID = 5 , Name = "E", IsValid = true }
                    }
                },
                new Customer
                {
                    ID = 3,
                    Name = "Ali",
                    Contacts = new List<Contact>()
                }
            };

我需要返回每个客户，并且每个客户仅包含IsValid = true联系人，该客户不包含IsValid Contacts Displays无联系人的主干，LINQ如何做到这一点？

Answer 1

List<Customer> customersResult = customers.Select(x => new Customer {
    ID = x.ID,
    Name = x.Name,
    Contacts = x.Contacts?.Where(c => c.IsValid).ToList()
}).ToList();

Linq to SQL每个客户中的有效联系人

1 个答案: