using xpath get the correct value in selectName

Question

Below I have written the code. I need help to get the right value in selectName. I am new to XPath. Basically with this code I am trying to achieve if employeeName = Chris I need to return 23549 to the calling function. Please help.

Part of the code:

public static string getEmployeeeID(string employeeName)
{

    Cache cache = HttpContext.Current.Cache;
    string cacheNameEmployee = employeeName + "Tech";

if (cache[cacheNameEpm] == null)
        {
            XPathDocument doc = new XPathDocument(HttpContext.Current.Request.MapPath("inc/xml/" + SiteManager.Site.ToString() + "TechToolTip.xml"));
            XPathNavigator navigator = doc.CreateNavigator();
            string selectName = "/Technologies/Technology[FieldName='" + fieldName + "']/EpmId";
            XPathNodeIterator nodes = navigator.Select(selectName);

            if (nodes.Count > 0)
            {
                if (nodes.Current.Name.Equals("FieldName"))
                //nodes.Current.MoveToParent();
                //nodes.Current.MoveToParent();
                //nodes.Current.MoveToChild("//EpmId");

                cache.Add(cacheNameEpm, nodes.Current.Value, null, DateTime.Now + new TimeSpan(4, 0, 0), System.Web.Caching.Cache.NoSlidingExpiration, CacheItemPriority.Default, null);
            }
        }
        return  cache[cacheNameEpm] as string;
    }

XML file

<?xml version="1.0" encoding="utf-8" ?>

<Employees>
  <Employee>
    <EName>Chris</EName>
    <ID>23556</ID>
  </Employee>
  <Employee>
    <EName>CBailey</EName>
    <ID>22222</ID>
  </Employee>
  <Employee>
    <EName>Meghan</EName>
    <ID>12345</ID>
  </Employee>
</Employees>

PLEASE NOTE:This XML file has 100 nodes. I just put 1 to indicate the structure.

Answer 1

Several things:

• the slash characters do not need to be doubled ex "/Employee/EName" (unless there may be additional nodes between the nodes listed)
• the first path should be: "/Employees/Employee[EName='" + employeeName + "']";
• the second path should be "ID" (case sensitive, for sure)

• the current locig seems to have one too many GotoParent

  regarding the statement of not using //, I'm not sure, it depends on the XML schema. I don't understand why moving back to parents etc.. maybe if you elaborate on this, we can make sense of it.....

Some of my confusion is with trying to reuse the current logic. In truth you would only need one XPATH navigation to get you what you need:

"/Employees/Employee[EName="' + employeeName + "']/ID"

The above means: from the root (single starting slash), find child element , then it child which has a child named EName with a value of employeeName. Then get the ID "sibling" of this EName node.

Some of my hesitation however is with the double slashes, which in XPATH mean any node done the path not necessary the next one. If all the Employee records are not going to be like the one shown in the sample, you may need it, and maybe complicate the XPATH part that get the ID, acordingly.

EDIT: one last thing... (explaining why you are getting all the values in the file rather than just the ID for the selected employee name)

You need to call nodes.MoveNext(), prior to using the XPathNodeIterator Current property. In short the section following the navigator.Select() call could be like:

if (nodes.Count == 0)
{
    return ""; // not found !
}
else
{
    nodes.MoveNext();    // <<< That was the missing culprit...
    retVal = nodes.Current.Value;
}

Answer 2

If you want to get the "ID" value for the employee called "Chris", you should be able to do this:

string selectName = "/Employees/Employee[EName='" + employeeName + "']/ID";
XPathNodeIterator idNode = navigator.Select(selectName);

This should give you the XPath:

/Employees/Employee[EName='Chris']/ID

and that should select that particular node right away. It gives you the ID element of the Employee with the EName=Chris inside the Employees collection; that's what you're looking for, right?

If you want to select just single node and inspect its values, use this snippet of code:

XPathNavigator empNode = navigator.SelectSingleNode(selectName);

if(empNode != null)
{
   string id = empNode.Value;
}

If you want only a single node - why do you use the Select method which returns an iterator over a whole list of nodes anyway?

Or if you want to stick to your original approach for some reason, you need to do a .MoveNext() first before reading the value:

XPathNodeIterator nodes = navigator.Select(selectName);

if (nodes.Count > 0)
{
   if (nodes.MoveNext())
   {
       string IDvalue = nodes.Current.Value;
   }
}

Now, in this case, you have just Chris' ID's value in your string.

Marc