从下拉列表中检索选定的枚举
本文关键字:枚举 检索 下拉列表 | 更新日期: 2023-09-27 17:52:13
我在asp.net 4.0 c#中将枚举绑定到下拉列表
Enumernation是:
public enum Frequency
{
[Description("Select a frequency")]
None,
[Description("Every Hour/Mintues")]
EveryHourOrMintues,
[Description("Previous Day Data")]
PreviousDayData,
[Description("Once a week")]
OnceaWeek
}
从下拉菜单中选择一个值,我想要返回enum值:我是这样做的:
Frequency selectedFrequency;
foreach (Frequency f in Enum.GetValues(typeof(Frequency)))
{
if (f.ToString().Equals(this.dropDownListFrequency.SelectedValue))
{
selectedFrequency = f;
break;
}
}
它正在工作,但绝对是一个糟糕的方式,我猜,通过循环遍历enum中的每个项目(即使enum非常小)
如何检索选定的enum,如:
Frequency selectedValue = Enum.GetValues(typeof(Frequency)).Cast<Frequency>().Select(f => f.ToString().Equals(this.dropDownListFrequency.SelectedValue));
我明白上面给出的代码有强制类型转换问题。
编辑要了解更多信息,下面是我如何将enum绑定到下拉列表
var frequencies = Enum.GetValues(typeof(Frequency)).Cast<Frequency>().Select(f => new
{
Text = f.ToDescriptiveTextUsingAttributes(),
Value = f.ToString()
});
this.dropDownListFrequency.DataSource=frequencies ;
this.dropDownListFrequency.DataTextField = "Text";
this.dropDownListFrequency.DataValueField = "Value";
ToDescriptiveTextUsingAttributes()是一个扩展方法,返回enum
如果下拉列表的值是enum的整数表示形式(例如0,1,2…),那么你可以简单地将其强制转换回enum:
Frequency f = (Frequency)int.Parse(dropDownListFrequency.SelectedValue);
如果下拉列表的值是枚举的字符串表示形式(例如:"None", "EveryHourOrMintues"…),那么您可以使用Enum.Parse()
:
Frequency f = (Frequency)Enum.Parse(
typeof(Frequency), dropDownListFrequency.SelectedValue);
您可以扩展ListItem
类来存储实际的Frequency
枚举对象,并将专门的ListItem
对象添加到dropDownListFrequency.Items
中。当您检索dropdownListFrequency.SelectedItem
时,您可以获得选定的实际值。
class FrequencyListItem : System.Web.UI.WebControls.ListItem.ListItem {
private Frequency _Frequency;
public Frequency Frequency {
get { return _Frequency }
}
public FrequencyListItem (Frequency f) {
this._Frequency = f;
this.Text = f.ToDescriptiveTextUsingAttributes();
this.Value = f.ToString();
}
}
由于Items
属性中的所有元素都是您的专门化类,因此您可以轻松地检索枚举值,如下所示:
Frequency selectedFrequency = ((FrequencyListItem )this.dropDownListFrequency.SelectedItem).Frequency;
编辑:你甚至可以使用相同的绑定模型,你有一些小的改变:
var frequencies = Enum.GetValues(typeof(Frequency)).Cast<Frequency>().Select(f => new FrequencyListItem()
{
//FrequencyListItem will auto set this in the constructor for you!
//Text = f.ToDescriptiveTextUsingAttributes(),
//Value = f.ToString()
});
this.dropDownListFrequency.DataSource=frequencies;
this.dropDownListFrequency.DataTextField = "Text";
this.dropDownListFrequency.DataValueField = "Value";