.NET数据绑定组合框的字符串枚举与描述属性 [英] .NET databinding a combobox to a string enum with Description attributes

问题描述

我有一个这样的枚举：

public enum Cities
{
    [Description("New York City")]
    NewYork,
    [Description("Los Angeles")]
    LosAngeles,
    Washington,
    [Description("San Antonio")]
    SanAntonio,
    Chicago
}

我想结合这一个组合框，我已经尝试过这样的：

I want to bind this to a combobox and I've tried this:

comboBox.DataSource = Enum.GetNames(typeof(Cities));

但是，这显示在组合框中，而不是字符串描述的值。所以，我切换到这一点：

But that displays the values in the combobox rather than the String description. So I switched to this:

public static string GetEnumDescription(Enum value)
{
    FieldInfo fi = value.GetType().GetField(value.ToString());

    DescriptionAttribute[] attributes = (DescriptionAttribute[])fi.GetCustomAttributes(typeof(DescriptionAttribute), false);

    if (attributes != null && attributes.Length > 0)
    {
        return attributes[0].Description;
    }
    else
    {
        return value.ToString();
    }
}

public static IList ToList(this Type type)
{
    ArrayList list = new ArrayList();
    Array enumValues = Enum.GetValues(type);

    foreach (Enum value in enumValues)
    {
        list.Add(new KeyValuePair<Enum, string>(value, GetEnumDescription(value)));
    }

    return list;
}

现在的价值list.Add（）调用的结果，它的显示在组合框中字符串描述让我换成

Now the list.Add() call results in the value and it's string description being displayed in the combobox so I replaced

list.Add(new KeyValuePair<Enum, string>(value, GetEnumDescription(value)));

与

list.Add(GetEnumDescription(value));

，现在我想起来的这是我最终想要的下拉列表中显示的描述字符串。现在我的数据绑定被打破，因为它无法找到刚才枚举中的字符串描述。我想这可能与combobox.DisplayMember和combobox.ValueMember，但我一直没能解决这个问题呢。谁能告诉我如何赫克我显示的描述字符串，但有我的数据绑定使用值存储，等等？谢谢！

and now I'm getting just the descriptive string displayed in the combobox which is what I ultimately want. Now my data binding is broken because it can't find just the string description in the enumeration. I thought this might be related to combobox.DisplayMember and combobox.ValueMember but I haven't been able to resolve the problem yet. Can anyone tell me how the heck I display the descriptive string but have my data binding use the value for storing, etc.? Thank you!!!

推荐答案

让我们回到你的问题我answered前几天和修改，以满足您新的要求。所以，我会守在原地的城市枚举在这个问题的 colorEnum 的例子。

Let's go back to your question I answered a few days ago and modify that to suit your new requirements. So I'll keep the colorEnum example in place of your Cities enum in this question.

您是大部分的方式出现 - 你已经得到了code从枚举描述字符串去;现在你只需要回去的其他方式。

You're most of the way there - you've got the code to go from the enum to the description string; now you just need to go back the other way.

public static class EnumHelper
{
    // your enum->string method (I just decluttered it a bit :))
    public static string GetEnumDescription(Enum value)
    {
        var fi = value.GetType().GetField(value.ToString());
        var attributes = fi.GetCustomAttributes(typeof(DescriptionAttribute), false);

        if (attributes.Length > 0)
            return ((DescriptionAttribute)attributes[0]).Description;
        else
            return value.ToString();        
    }

    // the method to go from string->enum
    public static T GetEnumFromDescription<T>(string stringValue)
        where T : struct
    {
        foreach (object e in Enum.GetValues(typeof(T)))           
            if (GetEnumDescription((Enum)e).Equals(stringValue))
                return (T)e;
        throw new ArgumentException("No matching enum value found.");
    }

    // and a method to get a list of string values - no KeyValuePair needed
    public static IEnumerable<string> GetEnumDescriptions(Type enumType)
    {
        var strings = new Collection<string>();
        foreach (Enum e in Enum.GetValues(enumType))   
            strings.Add(GetEnumDescription(e));
        return strings;
    }
}

现在，把你​​有什么前几天...

Now, take what you had a few days ago...

public class Person 
{
    [...]
    public colorEnum FavoriteColor { get; set; }
    public string FavoriteColorString
    {
        get { return FavoriteColor.ToString(); }
        set { FavoriteColor = (colorEnum)Enum.Parse(typeof(colorEnum), value);  }
    }
}

和刚刚改成这样：

public class Person 
{
    [...]
    public colorEnum FavoriteColor { get; set; }
    public string FavoriteColorString
    {
        get { return EnumHelper.GetEnumDescription(FavoriteColor); }
        set { FavoriteColor = EnumHelper.GetEnumFromDescription<colorEnum>(value); }
    }
}

和以前一样，你会绑定组合框的SelectedItem 值 FavoriteColorString 。你并不需要，如果你还在使用的BindingSource因为你在其他的问题，我认为你是设置的DisplayMember和ValueMember属性。

As before, you'll bind the combobox SelectedItem value to FavoriteColorString. You don't need to set the DisplayMember or ValueMember properties if you're still using the BindingSource as you were in the other question, which I assume you are.

和改变组合框的填充code：

And change the combobox populating code from:

comboBoxFavoriteColor.DataSource = Enum.GetNames(typeof(colorEnum));

到

comboBoxFavoriteColor.DataSource = EnumHelper.GetEnumDescriptions(typeof(colorEnum));

现在您拥有了世界上最好的。用户看到的描述，你的code包含枚举名称，数据存储包含枚举值。

Now you have the best of all worlds. The user sees the description, your code contains the enum names, and the data store contains the enum values.

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