从字符串获取一个枚举的场 [英] Get an enumerated field from a string

问题描述

一个奇怪的这一点位。请原谅下面的半伪code。我有枚举值的列表。比方说，例如，像这样：

Bit of a strange one this. Please forgive the semi-pseudo code below. I have a list of enumerated values. Let's say for instance, like so:

public enum Types
    {
       foo = 1,
       bar = 2,
       baz = 3
    }

这将成为，恭敬，在code：

Which would become, respectfully, in the code:

Types.foo
Types.bar
Types.baz

现在我有一个下拉列表，其中包含以下列表项：

Now I have a drop down list that contains the following List Items:

var li1 = new ListItem() { Key = "foo" Value = "Actual Representation of Foo" }
var li2 = new ListItem() { Key = "bar" Value = "Actual Representation of Bar" }
var li3 = new ListItem() { Key = "baz" Value = "Actual Representation of Baz" }

有关完整起见：

dropDownListId.Items.Add(li1); dropDownListId.Items.Add(li2); dropDownListId.Items.Add(li3);

希望大家还是和我在一起。我想要做的是对的AutoPostBack就是以字符串foo和将其转换成Types.foo - 不使用开关（如枚举值从数据库中生成并可能改变）

Hope that everyone is still with me. What I want to do is to on the Autopostback is take the string "foo" and convert that to Types.foo - without using a switch (as the enumerated values are generated from a database and may change).

我希望是有道理？任何想法，甚至开始？

I hope that makes sense? Any idea where to even start?

推荐答案

当然：

Types t;
if(Enum.TryParse(yourString, out t)) // yourString is "foo", for example
{
    // use t
}
else
{
    // yourString does not contain a valid Types value
}

还有，需要一个布尔值，它允许你指定的情况下不敏感的过载：
http://msdn.microsoft.com/en-us/library/dd991317.aspx

Enum.TryParse 是.NET 4的新如果你被困在一个previous版本，你将不得不使用非类型安全< A HREF =htt​​p://msdn.microsoft.com/en-us/library/essfb559.aspx相对=nofollow> Enum.Parse 方法（罚全中转换失败的情况下的异常，而不是返回假），像这样：

Enum.TryParse is new in .NET 4. If you're stuck on a previous version, you'll have to use the non-typesafe Enum.Parse method (which throws an exception in case of conversion failure, instead of returning false), like so:

try
{
    Types t = (Types)Enum.Parse(typeof(Types), yourString);
    // use t
}
catch(ArgumentException)
{
    // yourString does not contain a valid Types value
}

Enum.Parse 也有情况不敏感的过剩。

Enum.Parse also has an overload for case insensitiveness.

这篇关于从字符串获取一个枚举的场的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！