Question

重要提示：我想使用Linq执行此操作。

我有一个设备列表，其中有一个选项列表。假设有5个设备，每个设备都有几个选项。

现在我需要获取其选项名称包含＆＃34;脚踏板＆＃34;并将其安装设置为＆＃34; true＆＃34;。

由于

代码如下：

public class Device
{
    public Int32 ID { get; set; }
    public String Name { get; set; }
    public List<Option> Options { get; set; }
}

public class Option
{
    public Int32 ID { get; set; }
    public String Name { get; set; }
    public Boolean Installed { get; set; }
}

public class DeviceTest
{
    public DeviceTest()
    {
        List<Device> devices = new List<Device>();
        Option option;
        Device device;

        device = new Device();
        device.ID = 1;
        device.Name = "WC-1";
        devices.Add(device);

        device.Options = new List<Option>();
        option = new Option();
        option.ID = 1001;
        option.Name = "Foot pedal";
        option.Installed = true;
        device.Options.Add(option);

        option = new Option();
        option.ID = 1002;
        option.Name = "Wheel";
        option.Installed = true;
        device.Options.Add(option);

        device = new Device();
        device.ID = 2;
        device.Name = "WC-2";
        devices.Add(device);

        device.Options = new List<Option>();
        option = new Option();
        option.ID = 1003;
        option.Name = "Foot pedal";
        option.Installed = true;
        device.Options.Add(option);

        option = new Option();
        option.ID = 1004;
        option.Name = "Wheel";
        option.Installed = true;
        device.Options.Add(option);

        device = new Device();
        device.ID = 3;
        device.Name = "WC-3";
        devices.Add(device);

        device.Options = new List<Option>();
        option = new Option();
        option.ID = 1005;
        option.Name = "Foot pedal";
        option.Installed = false;
        device.Options.Add(option);

        option = new Option();
        option.ID = 1006;
        option.Name = "Wheel";
        option.Installed = true;
        device.Options.Add(option);

        device = new Device();
        device.ID = 4;
        device.Name = "WC-4";
        devices.Add(device);

        device.Options = new List<Option>();
        option = new Option();
        option.ID = 1007;
        option.Name = "Foot pedal";
        option.Installed = false;
        device.Options.Add(option);

        option = new Option();
        option.ID = 1008;
        option.Name = "Wheel";
        option.Installed = false;
        device.Options.Add(option);
    }
}

Answer 1

这是一个非常简单的查询：

allDevices.Where(d => d.Options.Any(o => o.Name == "Foot Pedal" && o.Installed));

请记住，lambda只是一个函数。它可以调用其他函数，声明变量以及普通代码中可以执行的所有其他操作。

Answer 2

var targetDevices = devices.Where(i => i.Options.Any(j => j.Installed && j.Name == "Foot pedal")).ToList()

或

var targetDevice = 
  (from device in devices 
   from option in device.Options
   where option.Installed && option.Name == "Foot pedal"
   select device).ToList()

注意最后的ToList（），如果结果为null，则返回空列表而不是null。

Linq和列表清单

2 个答案: