How to Get String Representation of Enum Values in C#?

String Representation of an Enum

Consider the following enumeration:

public enum AuthenticationMethod
{
    FORMS = 1,
    WINDOWSAUTHENTICATION = 2,
    SINGLESIGNON = 3
}

However, you require the string "FORMS" when requesting AuthenticationMethod.FORMS, not the ID of 1.

The "StringValue" custom attribute can address this issue:

public class StringValue : System.Attribute
{
    private readonly string _value;

    public StringValue(string value)
    {
        _value = value;
    }

    public string Value
    {
        get { return _value; }
    }

}

Then, you can apply this attribute to your enumeration:

public enum AuthenticationMethod
{
    [StringValue("FORMS")]
    FORMS = 1,
    [StringValue("WINDOWS")]
    WINDOWSAUTHENTICATION = 2,
    [StringValue("SSO")]
    SINGLESIGNON = 3
}

To retrieve this StringValue, you'll need the following:

public static class StringEnum
{
    public static string GetStringValue(Enum value)
    {
        string output = null;
        Type type = value.GetType();

        // Look for our 'StringValueAttribute' in the field's custom attributes
        FieldInfo fi = type.GetField(value.ToString());
        StringValue[] attrs = fi.GetCustomAttributes(typeof(StringValue), false) as StringValue[];
        if (attrs.Length > 0)
        {
            output = attrs[0].Value;
        }

        return output;
    }
}

This solution allows you to obtain the string value for enumerations like this:

string valueOfAuthenticationMethod = StringEnum.GetStringValue(AuthenticationMethod.FORMS);

However, a better solution is the type-safe-enum pattern:

public sealed class AuthenticationMethod {

    private readonly String name;
    private readonly int value;

    public static readonly AuthenticationMethod FORMS = new AuthenticationMethod (1, "FORMS");
    public static readonly AuthenticationMethod WINDOWSAUTHENTICATION = new AuthenticationMethod (2, "WINDOWS");
    public static readonly AuthenticationMethod SINGLESIGNON = new AuthenticationMethod (3, "SSN");        

    private AuthenticationMethod(int value, String name){
        this.name = name;
        this.value = value;
    }

    public override String ToString(){
        return name;
    }

}

For explicit (or implicit) type conversion, add a static field with mapping, fill the mapping in the instance constructor, and add a user-defined type conversion operator:

private static readonly Dictionary<string, AuthenticationMethod> instance = new Dictionary<string,AuthenticationMethod>();<br>instance[name] = this;<br>public static explicit operator AuthenticationMethod(string str)<br>{</p>
<pre class="brush:php;toolbar:false">AuthenticationMethod result;
if (instance.TryGetValue(str, out result))
    return result;
else
    throw new InvalidCastException();

}

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