遍历自定义枚举的属性

Question

Is it possible to iterate through properties of a custom enum?

My custom enum looks like this:

public class Sex
{
    public static readonly Sex Female = new Sex("xx", "Female");

    public static readonly Sex Male = new Sex("xy", "Male");

    internal string Value { get; private set; }

    internal string Description { get; private set; }

    public override string ToString()
    {
        return Value.ToString();
    }

    public string GetDescription()
    {
        return this.Description;
    }

    protected Sex(string value, string description)
    {
        this.Value = value;
        this.Description = description;
    }

I use it to enable an enum to "enumerate" with strings ie "xx", "xy"...

My question is if it is possible to iterate though all sexes with the goal to fill a DropDownList ListItems with value and description.

var ddlSex = new DropDownList()

foreach(var sex in typeof(Sex).<some_magic>)
{
    ddlSex.Items.Add(new ListItem(sex.ToString(), sex.GetDescription()));
}

My idea is to solve the problem with the System.Reflection library but I'm sure how.

Answer 1

var list = typeof(Sex).GetFields(BindingFlags.Static | BindingFlags.Public)
            .Select(f => (Sex)f.GetValue(null))
            .ToList();

foreach(var sex in list)
{
    Console.WriteLine(sex.ToString() + ":" + sex.GetDescription());
}

Answer 2

When you use reflection, you should try to do it in one hit: usually in a static constructor.

Here, you could do this:

public class Sex
{
    public static readonly List<Sex> All = typeof(Sex).GetFields(BindingFlags.Public | BindingFlags.Static)
        .Where(f => f.FieldType == typeof(Sex))
        .Select(f => (Sex)f.GetValue(null))
        .ToList();

    public static readonly Sex Female = new Sex("xx", "Female");

    public static readonly Sex Male = new Sex("xy", "Male");

    ...
}

Then you can just use Sex.All , and the reflection will only happen once in your runtime. Your invocation will look like this:

foreach(var sex in Sex.All)
{
    this.ddlSex.Items.Add(new ListItem(sex.ToString(), sex.GetDescription()));
}