Question

我有一个Object，MyRoot带有DateTime和List。我如何使用WHERE语句缩小列表范围，但仍然返回MyRoot和列表以缩小结果？

这是我的课程：

public class MyRoot 
{
    public DateTime LastUpdated { get; set; }
    public MyRates Rates { get; set; }
}

public class MyRates
{
    public string Type { get; set; }
    public string Rate { get; set; }
}

示例代码：

var rateList = new List<MyRates>() { 
   new MyRate { Type = "A", Program = "ABC", Rate = "1.0" },
   new MyRate { Type = "B", Program = "DEF", Rate = "1.5" },
   new MyRate { Type = "B", Program = "XYZ", Rate = "2.5" },
};

var myRoot = new MyRoot { RatesAsOf = "2016-11-09", Rates = ratesList };

问题：我无法弄清楚如何在myRoot rateList Type = "B"之前返回{{1}}对象感谢您的帮助！

Answer 1

根据您的问题，我认为您需要更改模型以创建Rate属性作为MyRates列表，并添加属性程序

public class MyRoot
    {
        public DateTime LastUpdated { get; set; }
        public List<MyRates> Rates { get; set; }
    }

public class MyRates
{
    public string Type { get; set; }

    public string Rate { get; set;}
    public string Program { get; set; }
}

这里的主要方法应该是

        static void Main(string[] args)
        {
            var rateList = new List<MyRates>()
            {
                new MyRates {Type = "A", Program = "ABC", Rate = "1.0"},
                new MyRates {Type = "B", Program = "DEF", Rate = "1.5"},
                new MyRates {Type = "B", Program = "XYZ", Rate = "2.5"},
            };

            var myRoot = new MyRoot { LastUpdated = DateTime.Parse("2016-11-09"), Rates = rateList };

            var list = rateList.Where(x => x.Type == "B");

            //OR try to create a new object
            myRoot = new MyRoot {LastUpdated = myRoot.LastUpdated, Rates = myRoot.Rates.Where(x => x.Type == "B").ToList() };


            Console.ReadLine();
        }

Answer 2

var myFilteredList = rateList.Where(x=> x.Type == "B");

就是这样。 Where是一个lambda表达式，它返回集合中具有Type = B的任何内容。

Answer 3

var myRoot = new MyRoot { RatesAsOf = "2016-11-09", Rates = ratesList.Where(r=>r.Type == "B") };

你真的需要阅读LINQ。这是基本的东西。

Answer 4

试试这个：

var myRoot = new MyRoot {RatesAsOf =“2016-11-09”，Rates = ratesList};

var myRoot1 = new MyRoot {LastUpdated = myRoot.LastUpdated，Rates = myRoot.Rates.Where（x =＆gt; x.Type ==“A”）。ToList（）};

使用WHERE返回带有列表但过滤列表的对象

4 个答案: