Enum Parse Extension Methods

When I write code I don't like to depend on catching exceptions to control my programming logic, so as much as I can I try to check for nulls, empty, etc...

When parsing one type into another there are usually TryParse() methods available so that an exception does not occur. I've always been a little confused why there wasn't such a method off the Enum class. So, I decided to make my own.

However, after I started to extend the TryParse method off of the Enum, the answer started to become clear why that was not a feature :) I could extend the actual specific enum, but that didn't really help me any. I wanted a Generic solution for all enums.

So, instead of making an Enum.TryParse(), I decided to extend the string class to add string.ToEnum() and string.TryToEnum(). The string is usually the class that I want to parse into a specific Enum after all.

The following is the Extension methods that I created...


using System;

namespace Web.Helpers {
public static class EnumHelper {
public static bool TryToEnum(this string obj, out T parsed) {
bool isParsed = false;

if (Enum.IsDefined(typeof(T), obj)) {
parsed = (T)Enum.Parse(typeof(T), obj);
isParsed = true;
} else {
parsed = (T)Enum.Parse(typeof(T), Enum.GetNames(typeof(T))[0]);
}

return isParsed;
}

public static T ToEnum(this string obj) {
return (T)Enum.Parse(typeof(T), obj);
}
}
}
</pre>

I created a set of 4 MS Unit tests to exercise different scenarios that might exist. Let me know if you see any other tests that I should test.


using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Web.Helpers;

namespace WebTests.Generic {
[TestClass]
public class EnumTest {
public enum Color { Red, Orange, Yellow, Green, Blue, Indigo, Violet };

[TestMethod]
public void TryToEnumWorksWithValidEnum() {
Color parsedColor = Color.Blue;

string realColor = "Yellow";
bool canParse = realColor.TryToEnum(out parsedColor);
Assert.AreEqual(true, canParse);
}

[TestMethod]
public void TryToEnumWorksWithInvalidEnum() {
Color parsedColor = Color.Blue;

string fakeColor = "Elijahish";
bool canParse = fakeColor.TryToEnum(out parsedColor);
Assert.AreEqual(false, canParse);
}

[TestMethod]
public void ToEnumWorksWithValidEnum() {
Color parsedColor = Color.Blue;

string realColor = "Yellow";
parsedColor = realColor.ToEnum();
Assert.AreEqual(Color.Yellow, parsedColor);
}

[TestMethod, ExpectedException(typeof(ArgumentException), "Unable to parse enum")]
public void ToEnumThrowsExceptionWithInalidEnum() {
Color parsedColor = Color.Blue;

string fakeColor = "Elijahish";
parsedColor = fakeColor.ToEnum();
}
}
}
</pre>

Have you found yourself doing some sort of the same thing? If so, how?

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