Check if XAttribute exists inside XElement

Hey experts!

I am working on pulling ASP.NET MVC routes from an external file, and it's going well at the moment. My problem is that I want to be able to return the 'controller' attribute from the 'page' element, or the 'controller' attribute from the 'dir' element (parent of the 'page' element).

The problem is that when this runs, it causes an exception (ArgumentNullException) because I'm trying to retrieve the value of an attribute that doesn't exist.

I realise that, in the snippet, retrieving ControllerName is invalid, but I was trying to highlight what I want to  retrieve.

Any help would be great!

Thanks in advance!

XDocument xDoc = XDocument.Load("urls.xml");
var pages =
  from x in xDoc.Descendants().Elements("page")
  select new
  {
    Name = x.Parent.Attribute("name").Value,
    ControllerName = x.Attribute("controller").Value || x.Parent.Attribute("controller").Value,
    ControllerAction = x.Attribute("action").Value,
    Dir = x.Parent.Attribute("name").Value,
    Url = x.Parent.Attribute("name").Value + "/" + x.Attribute("url").Value,
  };
 
//An example of the urls.xml files is thus:
//
//<urls>
//  <dir name="Cheese" controller="Food"> <!-- Always a 'controller' attr on the 'dir' node -->
//    <page url="mexican.htm" action="mexican" controller="bar" />
//    <page url="cheddar.htm" action="cheddar" /> <!-- Note, no controller attribute here ('controller' attr is optional in 'page' node -->
//    <!--...-->
//  </dir>
//  <dir name="Alcohol" controller="Drink">
//  <!--...-->
//  </dir>
//</urls>

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