是否有更好的方法来设置linq中项目列表的公共属性

本文关键字：列表 项目 属性 设置 更好 方法 是否 linq | 更新日期: 2023-09-27 18:13:40

我有以下类:

public class Vehicle
{
    public string Make { get; set; }
    public DateTime DateManufactured { get; set; }
}

然后我列出了一个车辆列表，如:

        var dateTime1 = DateTime.Now.AddDays(-7);
        var dateTime2 = DateTime.Now.AddDays(-8);
        var dateTime3 = DateTime.Now.AddDays(-9);
        var vehicles = new List<Vehicle>
            {
                new Vehicle {Make = "Ferrari", DateManufactured = dateTime1},
                new Vehicle {Make = "Mazda", DateManufactured = dateTime2},
                new Vehicle {Make = "Dodge", DateManufactured = dateTime3},
                new Vehicle {Make = "Holden", DateManufactured = dateTime1},
                new Vehicle {Make = "Chrysler", DateManufactured = dateTime2},
                new Vehicle {Make = "Mazda", DateManufactured = dateTime3},
            };

接下来，我试图获取DatesManufactured的列表，以及每个日期在该日期制造的车辆。

所以我选择:

var vehiclesGroupedByDate = vechicles.GroupBy(x => x.DateManufactured)
                .Select(x => new
                    {
                        x.First().DateManufactured,
                        Vehicles = x.ToList()
                    });

这工作很好，但我不确定x.First()部分。它可以工作，但感觉不太对。有人知道更优雅的编码方式吗?

是否有更好的方法来设置linq中项目列表的公共属性

当您使用GroupBy时，它将创建一个IGrouping<TKey, TItem>，因此您可以简单地执行以下操作:

var vehiclesGroupedByDate = vechicles.GroupBy(x => x.DateManufactured)
            .Select(x => new
                {
                    x.Key,
                    Vehicles = x.ToList()
                });

我没有看到你的代码有任何问题，但你也可以使用x.Key代替x.First().DateManufactured，这将不需要创建另一个IEnumerable

GroupBy公开Key属性:

var vehiclesGroupedByDate = vechicles.GroupBy(x => x.DateManufactured)
    .Select(x => new
    {
        x.Key,
        Vehicles = x.ToList()
    });
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