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 =http://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.
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