How can I check if an int is a legit HttpStatusCode in .NET?

Question

I wish to make sure that the number a person provides, is a legit HttpStatusCode.

At first I thought of using Enum.TryParse(..) or Enum.Parse(..) but it's possible I get an invalid result with some bad data provided..

eg.

In: Enum.Parse(typeof (HttpStatusCode), "1")
Out: 1

In: Enum.Parse(typeof (HttpStatusCode), "400")
Out: BadRequest

In: Enum.Parse(typeof (HttpStatusCode), "aaa")
Out: System.ArgumentException: Requested value 'aaa' was not found.

Ok, so if I pass in a bad aaa value, I get the System.Argument exception. But when I pass in a number 1 (as text, not an int) i get the return value of 1. I would have expected this to fail and throw an exception.

Passing a value of 400 does return the correct BadRequest enumeration.

Any ideas, folks?

Answer 1

Instead of trying to parse the value simply us the IsDefined method

Enum.IsDefined(typeof(HttpStatusCode),value)

The reason why the case with "1" doesn't fail is that you can do binary arithmetic on enumerations. This is used a lot for flags, thus values not specifically in the enum might still be valid values

Answer 2

That is the documented behaviour:

If value is a name that does not correspond to a named constant of enumType, the method throws an ArgumentException. If value is the string representation of an integer that does not represent an underlying value of the enumType enumeration, the method returns an enumeration member whose underlying value is value converted to an integral type. If this behavior is undesirable, call the IsDefined method to ensure that a particular string representation of an integer is actually a member of enumType.