To fetch the attributes from the NodeList of XmlDocument?

Question

Hi Everyone, I have part of XmlDocument Example.xml as given below:

<rapaine dotoc="palin" domap="rattmin">
  <derif meet="local" />
  <derif meet="intro" />
.
.
.
</rapaine>

Here i am creating a Nodelist and fetching the element raplin to get its attributes.

Now i want to make sure that whether the attributes 'dotoc' and 'domap' are the attributes of rapaine with respective values which are always fixed.Then only i can access the childNodes 'deriff' with its attribute 'meet'. here the value only changes.
i have written a part of code there are no compile errors but on debugging i found that its not going inside the for loop to check its attributes and child nodes.

XmlNodeList listOfSpineRootNodes = opfXmlDoc.GetElementsByTagName("rapine");
for (int x = 0; x < listOfSpineRootNodes.Count; x++)
  {
    XmlAttributeCollection spineAttributes = listOfSpineRootNodes[x].Attributes;
    string id = spineAttributes[0].Value;
    if (spineAttributes != null)
    {
      XmlNode attrToc = spineAttributes.GetNamedItem("dotoc");
      XmlNode attrPageMap = spineAttributes.GetNamedItem("domap");
      if (attrToc.Value == "palin" && attrPageMap.Value == "rattmine")
      {
        if (listOfSpineRootNodes != null)
        {
          foreach (XmlNode spineNodeRoot in listOfSpineRootNodes)
          {
            XmlNodeList listOfSpineItemNodes = spineNodeRoot.ChildNodes;
            if (listOfSpineItemNodes != null)
            {
              foreach (XmlNode spineItemNode in listOfSpineItemNodes)
              {
                if (spineItemNode.NodeType == XmlNodeType.Element
                  && spineItemNode.Name == "derif")
                {
                  XmlAttributeCollection spineItemAttributes = spineItemNode.Attributes;

                  if (spineItemAttributes != null)
                  {
                    XmlNode attrIdRef = spineItemAttributes.GetNamedItem("meet");
                    if (attrIdRef != null)
                    {
                      spineListOfSmilFiles.Add(attrIdRef.Value);
                    }
                  }
                }
              }
            }
          }
        }
      }
    }

Can you please tell me where i am going wrong.. Thanks....

Answer 1

Can't you just fix this with a simple XPath expression?

All the nested loops with condition is simply asking for trouble.

Answer 2

depending on what version of .NET you use, LINQ might be able to simplify this.

Answer 3

You can do this with the following code using XPath. Since XPath is a language designed specifically to query XML documents, you should consider learning it. Most newbies like to start learning at W3schools.

Here is the code:

XmlNodeList meetList = opfXmlDoc.SelectNodes("/rapaine[(@dotoc = 'palin') and (@domap = 'rattmin')]/derif/@meet")
if (meetList.Count > 0)
{
  foreach (XmlNode meet in meetList)
  {
    spineListOfSmilFiles.Add(meet.Value);
  }
}

For your reference, the XPath expression:

/rapaine[(@dotoc = 'palin') and (@domap = 'rattmin')]/derif/@meet

can be explained as:

a) Find all rapaine root level elements that have an attribute dotoc with a value of "palin" and also have an attribute domap with a value "rattmin".

b) Within those rapaine elements, find all derif children.

c) Within those derif elements, retrieve all meet attributes.

Note how much more concise the code becomes.