Linq C＃条件列表

Question

I have simple class model Car with two fields

public class Car
{
    public string CarBrand { get; set; }
    public List<CarModel> carModel;         
}

public class CarModel
{
    public string Name { get; set; }
    public string YearOfProduction{ get; set; }
}

Now, my question is how to get new List of Cars List where YearOfProduction will be for example only 2016.

Answer 1

If you need a list of car where at least one of the car models belong to an specific year, you can do this:

var temp = cars.Where(c=>c.CarModels.Any(cm=>cm.YearOfProduction== Year)).ToList();

If all the car models have to belong to that year then use All extension method instead Any :

var temp = cars.Where(c=>c.CarModels.All(cm=>cm.YearOfProduction== Year)).ToList();

Answer 2

您正在寻找Any函数：

cars.Where(c => c.carModel.Any(cm => cm.YearOfProduction == 2016));

Answer 3

you can use Exists method for this query. Check the following example;

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

namespace ConsoleApplication1
{
    public class Car
    {
        public string CarBrand { get; set; }
        public List<CarModel> carModel;
    }

    public class CarModel
    {
        public string Name { get; set; }
        public string YearOfProduction { get; set; }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var list = new List<Car>();
            list.Add(
                new Car
                    {
                        CarBrand = "Ford",
                        carModel = new List<CarModel>{ 
                            new CarModel{Name="Fiesta", YearOfProduction="2010"},
                            new CarModel{Name="Fiesta", YearOfProduction="2011"},
                            new CarModel{Name="Fiesta", YearOfProduction="2012"},
                            new CarModel{Name="Fiesta", YearOfProduction="2013"},
                            new CarModel{Name="Fiesta", YearOfProduction="2014"},
                            new CarModel{Name="Fiesta", YearOfProduction="2015"},
                            new CarModel{Name="Fiesta", YearOfProduction="2016"},
                            new CarModel{Name="Mondeo", YearOfProduction="2010"},
                            new CarModel{Name="Mondeo", YearOfProduction="2011"},
                            new CarModel{Name="Mondeo", YearOfProduction="2012"},
                            new CarModel{Name="Mondeo", YearOfProduction="2013"},
                            new CarModel{Name="Mondeo", YearOfProduction="2014"},
                            new CarModel{Name="Mondeo", YearOfProduction="2015"},
                            new CarModel{Name="Mondeo", YearOfProduction="2016"},
                            new CarModel{Name="Focus", YearOfProduction="2010"},
                            new CarModel{Name="Focus", YearOfProduction="2011"},
                            new CarModel{Name="Focus", YearOfProduction="2012"},
                            new CarModel{Name="Focus", YearOfProduction="2013"},
                            new CarModel{Name="Focus", YearOfProduction="2014"},
                            new CarModel{Name="Focus", YearOfProduction="2015"},

                        }
                    }

                    );
            list.Add(new Car
                    {
                        CarBrand = "Volkswagen",
                        carModel = new List<CarModel>{ 
                            new CarModel{Name="Polo", YearOfProduction="2010"},
                            new CarModel{Name="Polo", YearOfProduction="2011"},
                            new CarModel{Name="Polo", YearOfProduction="2012"},
                            new CarModel{Name="Polo", YearOfProduction="2013"},
                            new CarModel{Name="Polo", YearOfProduction="2014"},
                            new CarModel{Name="Polo", YearOfProduction="2015"},
                            new CarModel{Name="Golf", YearOfProduction="2010"},
                            new CarModel{Name="Golf", YearOfProduction="2011"},
                            new CarModel{Name="Golf", YearOfProduction="2012"},
                            new CarModel{Name="Golf", YearOfProduction="2013"},
                            new CarModel{Name="Golf", YearOfProduction="2014"},
                            new CarModel{Name="Golf", YearOfProduction="2015"},
                            new CarModel{Name="Passat", YearOfProduction="2010"},
                            new CarModel{Name="Passat", YearOfProduction="2011"},
                            new CarModel{Name="Passat", YearOfProduction="2012"},
                            new CarModel{Name="Passat", YearOfProduction="2013"},
                            new CarModel{Name="Passat", YearOfProduction="2014"},
                            new CarModel{Name="Passat", YearOfProduction="2015"},

                        }
                    });

            var newCars = list.Where(s => s.carModel.Exists(m => m.YearOfProduction == "2016"));

            foreach (var brand in newCars)
            {
                foreach (var model in brand.carModel)
                {
                    Console.WriteLine("Brand:{0}, Model:{1}, YearOfPrd:{2}", brand.CarBrand, model.Name, model.YearOfProduction);

                }
            }
            Console.ReadLine();
        }
    }
}