Proper way to find the innermost exception?

Question

I\'m working with some classes which, when throwing, have a relatively deep InnerException tree. I\'d like to log and act upon the innermost exception which is the one having th

Answer 1

There are exceptions that can have multiple root causes (e.g. AggregateException and ReflectionTypeLoadException).

I created my own class to navigate the tree and then different visitors to either collect everything or just the root causes. Sample outputs here. Relevant code snippet below.

public void Accept(ExceptionVisitor visitor)
{
    Read(this.exception, visitor);
}

private static void Read(Exception ex, ExceptionVisitor visitor)
{
    bool isRoot = ex.InnerException == null;
    if (isRoot)
    {
        visitor.VisitRootCause(ex);
    }

    visitor.Visit(ex);
    visitor.Depth++;

    bool isAggregateException = TestComplexExceptionType(ex, visitor, aggregateException => aggregateException.InnerExceptions);
    TestComplexExceptionType(ex, visitor, reflectionTypeLoadException => reflectionTypeLoadException.LoaderExceptions);

    // aggregate exceptions populate the first element from InnerExceptions, so no need to revisit
    if (!isRoot && !isAggregateException)
    {
        visitor.VisitInnerException(ex.InnerException);
        Read(ex.InnerException, visitor);
    }

    // set the depth back to current context
    visitor.Depth--;
}

private static bool TestComplexExceptionType(Exception ex, ExceptionVisitor visitor, Func> siblingEnumerator) where T : Exception
{
    var complexException = ex as T;
    if (complexException == null)
    {
        return false;
    }

    visitor.VisitComplexException(ex);

    foreach (Exception sibling in siblingEnumerator.Invoke(complexException))
    {
        visitor.VisitSiblingInnerException(sibling);
        Read(sibling, visitor);
    }

    return true;
}