How to locate a particular exception in a Exception stack

Question

Let us assume that a particular Exception "SomeException" is part of the exception stack,

so let us assume ex.InnerException.InnerException.InnerException is of type "SomeException"

Is there any built-in API in C# which will try to locate a given exception type in exception stack?

Example:

SomeException someExp = exp.LocateExceptionInStack(typeof(SomeException));

Answer 1

No, I don't believe there's any built in way of doing it. It's not hard to write though:

public static T LocateException<T>(Exception outer) where T : Exception
{
    while (outer != null)
    {
        T candidate = outer as T;
        if (candidate != null)
        {
            return candidate;
        }
        outer = outer.InnerException;
    }
    return null;
}

If you're using C# 3 you could make it an extension method (just make the parameter "this Exception outer") and it would be even nicer to use:

SomeException nested = originalException.Locate<SomeException>();

(Note the shortening of the name as well - adjust to your own taste :)

Answer 2

It's just 4 lines of code:

    public static bool Contains<T>(Exception exception)
        where T : Exception
    {
        if(exception is T)
            return true;

        return 
            exception.InnerException != null && 
            LocateExceptionInStack<T>(exception.InnerException);
    }