Question

我有一个看起来像这样的课程;

class MessageEntry
{
    public Tuple<bool, int> MessageId;

    public Tuple<bool, DateTime> MessageDate { get; internal set; }
    public Tuple<bool, String> Subject { get; internal set; }
    public Tuple<bool, String> EmailFrom { get; internal set; }
    public Tuple<bool, String> EmailTo { get; internal set; }
    public Tuple<bool, String> EmailCC { get; internal set; }
    public Tuple<bool, String> EmailBCC { get; internal set; }
    public Tuple<bool, String> EmailDateSent { get; internal set; }
    public Tuple<bool, String> BodyHTML { get; internal set; }
}

然后我有List<MessageEntry> - List<MessageEntry> test = new List<MessageEntry>。

如何选择元组test为Item1 true的{{1}}内的所有项目？

Answer 1

var result = test.Where(x => x.MessageDate.Item1 && x.Subject.Item1 && ....);

Answer 2

我不太明白你打算如何使用问题中的代码。但是我认为如果你根据自己的需要改变它，这段代码可以帮到你。

编辑（我在扩展方法中提取检查方法，在LINQ中使用样式）：

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

namespace ConsoleApplication1
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            var test = new List<MessageEntry>();

            var result = test
                .Where(entry => entry.IsAllTuplePropertiesIsTrue())
                .Aggregate(
                    string.Empty, 
                    (s, entry) => s + $"value is {entry.IsAllTuplePropertiesIsTrue()}"
                    );

            Console.WriteLine(result);
            Console.ReadLine();
        }
    }

    public static class MessageEntryExtension
    {
        private const BindingFlags BindingFlags = 
            System.Reflection.BindingFlags.GetProperty
            | System.Reflection.BindingFlags.Public
            | System.Reflection.BindingFlags.Instance;

        /// <summary>
        /// Method check all <see cref="Tuple" /> properties 
        /// in instance of <see cref="MessageEntry" /> class.
        /// </summary>
        /// <param name="messageEntry"></param>
        /// <returns>If one of several Tuple.Item1 value is not bool false not equal 
        /// false - return false. Any way - true</returns>
        public static bool IsAllTuplePropertiesIsTrue(this MessageEntry messageEntry)
        {
            var props = typeof (MessageEntry).GetProperties(BindingFlags);

            foreach (var value in props.Select(p => p.GetValue(messageEntry)))
            {
                if (value == null)
                    return false;

                if (typeof (Tuple<,>) == value.GetType())
                    return false;

                var item1Type = value.GetType().GetProperty("Item1", BindingFlags);
                var item1Value = item1Type?.GetValue(value);

                if (!(item1Value is bool))
                    return false;

                if (!(bool) item1Value)
                    return false;
            }

            return true;
        }
    }

    public class MessageEntry
    {
        public MessageEntry()
        {
            MessageId = new Tuple<bool, int>(true, 1);
            MessageDate = new Tuple<bool, DateTime>(false, DateTime.Now);
            Subject = new Tuple<bool, string>(true, "Hello, World!");
        }

        // Pay attention, I changed this place, 
        // so as not to duplicate the reflection code. 
        // For properties and field, it is similar, but still disconnects
        public Tuple<bool, int> MessageId { get; internal set; }

        public Tuple<bool, DateTime> MessageDate { get; internal set; }
        public Tuple<bool, string> Subject { get; internal set; }
        public Tuple<bool, string> EmailFrom { get; internal set; }
        public Tuple<bool, string> EmailTo { get; internal set; }
        public Tuple<bool, string> EmailCC { get; internal set; }
        public Tuple<bool, string> EmailBCC { get; internal set; }
        public Tuple<bool, string> EmailDateSent { get; internal set; }
        public Tuple<bool, string> BodyHTML { get; internal set; }
    }
}

从作为元组的对象列表中选择项目

2 个答案: