Deeply nested search through Document tree

I have this code block, where I search for the value of Ordnungsbegriff. I have to search through a tree of my CurrentDocument.

How can I rewrite it to be more dynamic? I don't know at which level I will find my value.

```
string xy = "";
try
{

if (string.IsNullOrEmpty(CurrentDocument.Ordnungsbegriff))
{
if (string.IsNullOrEmpty(CurrentDocument.ParentDocument.Ordnungsbegriff))
{
if (string.IsNullOrEmpty(CurrentDocument.ParentDocument.ParentDocument.Ordnungsbegriff))
{
if (string.IsNullOrEmpty(CurrentDocument.ParentDocument.ParentDocument.ParentDocument.Ordnungsbegriff))
{
if (string.IsNullOrEmpty(CurrentDocument.ParentDocument.ParentDocument.ParentDocument.ParentDocument.Ordnungsbegriff))
{
if (string.IsNullOrEmpty(CurrentDocument.ParentDocument.ParentDocument.ParentDocument.ParentDocument.ParentDocument.Ordnungsbegriff))
{
if (string.IsNullOrEmpty(CurrentDocument.ParentDocument.ParentDocument.ParentDocument.ParentDocument.ParentDocument.ParentDocument.Ordnungsbegriff))
{
xy = "Nach 6. Ebene, Suche abgebrochen.";
}
else
xy = CurrentDocument.ParentDocument.ParentDocument.ParentDocument.ParentDocument.ParentDocument.ParentDocument.Ordnungsbegriff;
}
else
xy = CurrentDocument.ParentDocument.ParentDocument.ParentDocument.ParentDocument.ParentDocument.Ordnungsbegriff;
}
else
xy = CurrentDocument.ParentDocument.ParentDocument.ParentDocument.ParentDocument.Ordnungsbegriff;
}
else
xy = CurrentDocument.ParentDocument.ParentDocument.Pare

I find recursion complicated You can use a while loop:

private string SearchDocument(Document doc)
{
    while (doc != null) 
    {
        if (!string.IsNullOrEmpty(doc.Ordnungsbegriff))
        {
            return doc.Ordnungsbegriff;
        }
        doc = doc.ParentDocument;
    }
    return null;
}

Edit: As a further point - it's better not to mix languages in your code: Ordnungsbegriff should be Keyword (according to Google).

StackExchange Code Review Q#85051, answer score: 10