c# - 从 C# 中的对象中获取分组数据

Question

我有一个数据:

data e1 = new data() { eventId = 1, eventName = "event1", hobbies = "hobbies1", note = "note1" };
data e2 = new data() { eventId = 1, eventName = "event1", hobbies = "hobbies2", note = "note2" };
data e3 = new data() { eventId = 2, eventName = "event2", hobbies = "hobbies3", note = "note3" };
data e4 = new data() { eventId = 2, eventName = "event2", hobbies = "hobbies4", note = "note4" };

我需要将其分组到 List<Event>基于 eventId 和 eventName 的类，eventDetails 应根据 eventId 和 eventName 分组为 List<EventDetails>包含“爱好”和“注意”值的属性。

public class Event
{
    public int eventId { get; set; }
    public string eventName { get; set; }
    public List<EventDetails> eventDetails { get; set; }
}

//i want to get a List<Event> which group e1,e2 together and e3,e4 together

这能做到吗？不确定我需要从哪里开始。我可以使用的最佳解决方案是什么？

Answer 1

您可以使用 GroupBy实现这一点的 LINQ 方法:

data e1 = new data() { eventId = 1, eventName = "event1", hobbies = "hobbies1", note = "note1" };
data e2 = new data() { eventId = 1, eventName = "event1", hobbies = "hobbies2", note = "note2" };
data e3 = new data() { eventId = 2, eventName = "event2", hobbies = "hobbies3", note = "note3" };
data e4 = new data() { eventId = 2, eventName = "event2", hobbies = "hobbies4", note = "note4" };

data[] arr = { e1, e2, e3, e4 };

List<Event> groupedList = arr.GroupBy(i => i.eventId)
    .Select(j => new Event()
    {
        eventId = j.First().eventId,
        eventName = j.First().eventName,
        eventDetail = j.Select(f => new EventDetails()
        {
            hobbies = f.hobbies,
            note = f.note
        }).ToList()
    })
    .ToList();