C# Enum.GetValues() 上的 OrderBy
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OrderBy on Enum.GetValues()
提问by Cameron Tinker
I'm populating a DropDownListin MVC 4 from an enumand I want to order the enum values from largest to smallest. However, there doesn't seem to be a direct way of approaching this. Currently, I'm using this code to add to a dictionary with the key being the ID and the value being the display text:
我正在DropDownList从 an填充MVC 4 中的 aenum并且我想从最大到最小对枚举值进行排序。但是，似乎没有直接的方法来解决这个问题。目前，我正在使用此代码添加到字典中，键是 ID，值是显示文本：
var priorities = Enum.GetValues(typeof(Models.Priority)).OfType<Models.Priority>().ToList();
for (int i = priorities.Count - 1; i >= 0; i--)
{
Models.Priority priority = priorities[i];
prioritiesDictionary.Add((int)priority, "Priority " + ((int)priority).ToString());
}
I don't believe that putting enum values into a list and looping backwards is the most efficient method. There are only four values in the enum, but is there a better way to perform an OrderByoperation on what is returned from Enum.GetValues? I know it might be minimal performance impact doing it the way I am, but I want to know for larger enums.
我不相信将枚举值放入列表并向后循环是最有效的方法。枚举中只有四个值，但是有没有更好的方法来OrderBy对返回的内容执行操作Enum.GetValues？我知道按照我的方式这样做可能对性能的影响很小，但我想知道更大的枚举。
采纳答案by Jon Skeet
Sounds like you just want:
听起来你只想：
var priorities = ((Models.Priority[]) Enum.GetValues(typeof(Models.Priority)))
.OrderByDescending(x => x);
Or to avoid quite as many brackets:
或者为了避免尽可能多的括号：
var priorities = (Models.Priority[]) Enum.GetValues(typeof(Models.Priority));
var ordered = priorities.OrderByDescending(x => x);
It's not clear how your current code is helping you, by giving you a dictionary - but the above will definitely give you a sequence of enum values, ordered from highest to lowest. You don't need to cast to int, because enum values of the same type are already comparable to each other.
目前尚不清楚您当前的代码如何通过为您提供字典来帮助您 - 但以上肯定会给您一个枚举值序列，从高到低排序。您不需要强制转换为int，因为相同类型的枚举值已经可以相互比较。
If you need a list, just call ToList()after the OrderByDescendingcall.
如果您需要清单，请ToList()在通话后OrderByDescending致电。
回答by usr
What about this:
那这个呢：
Enum.GetValues(typeof(Models.Priority))
.Cast<Models.Priority>()
.OrderBy(x => (int) x)
.ToList();
Don't use OfTypebecause that silently throws away non-matching items. It is almost always a mistake.
不要使用，OfType因为它会默默地丢弃不匹配的项目。这几乎总是一个错误。
回答by LawMan
Based on the above, I create a reusable function...
基于以上，我创建了一个可重用的函数......
public static IOrderedEnumerable<TEnum> Sort<TEnum>()
{
return ((TEnum[]) Enum.GetValues(typeof (TEnum))).OrderBy(x => x.ToString());
}
