Convert String to Enum based on enum name

Question

So we have our enums setup like this:

[CorrelatedNumeric(0)]
[Description("USD")]
[SequenceNumber(10)]
USD = 247

Basically, another function can provide the string "USD" to me, but not the exact enum because the source of it is Excel and we can't make our users remember the enum values ;) nor would that make much sense.

Is there a way in c# to get from "USD" to 247 from having our enums setup as they are above?

Answer 1

Enum.TryParse()或Enum.Parse()做你需要的吗？

Currency cValue = (Currency) Enum.Parse(typeof(Currency), currencyString); 

Answer 2

Absolutely - build a Dictionary<string, YourEnumType> by reflection. Just iterate over all the fields in the enum and find the attribute values, and build up the dictionary that way.

You can see how I've done something similar in Unconstrained Melody for the description attribute, in EnumInternals :

// In the static initializer...
ValueToDescriptionMap = new Dictionary<T, string>();
DescriptionToValueMap = new Dictionary<string, T>();
foreach (T value in Values)
{
    string description = GetDescription(value);
    ValueToDescriptionMap[value] = description;
    if (description != null && !DescriptionToValueMap.ContainsKey(description))
    {
        DescriptionToValueMap[description] = value;
    }
}

private static string GetDescription(T value)
{
    FieldInfo field = typeof(T).GetField(value.ToString());
    return field.GetCustomAttributes(typeof(DescriptionAttribute), false)
                .Cast<DescriptionAttribute>()
                .Select(x => x.Description)
                .FirstOrDefault();
}

Just do the same thing for your own attribute type.

Answer 3

 public static object enumValueOf(string description, Type enumType)
 {
      string[] names = Enum.GetNames(enumType);
      foreach (string name in names)
      {
          if (descriptionValueOf((Enum)Enum.Parse(enumType, name)).Equals(description))
           {
               return Enum.Parse(enumType, name);
           }
       }

       throw new ArgumentException("The string is not a description of the specified enum.");
  }

  public static string descriptionValueOf(Enum value)
  {
       FieldInfo fi = value.GetType().GetField(value.ToString());
       DescriptionAttribute[] attributes = (DescriptionAttribute[]) fi.GetCustomAttributes( typeof(DescriptionAttribute), false);
       if (attributes.Length > 0)
       {
             return attributes[0].Description;
       }
       else
       {
            return value.ToString();
       }
  }