Check if XML Element exists

Question

How can someone validate that a specific element exists in an XML file? Say I have an ever changing XML file and I need to verify every element exists before reading/parsing

Answer 1

 string name = "some node name";
    var xDoc = XDocument.Load("yourFile");
    var docRoot = xDoc.Element("your docs root name");

     var aNode = docRoot.Elements().Where(x => x.Name == name).FirstOrDefault();
                if (aNode == null)
                {
                    return $"file has no {name}";
                }

Answer 2

//if the problem is "just" to verify that the element exist in the xml-file before you //extract the value you could do like this

XmlNodeList YOURTEMPVARIABLE = doc.GetElementsByTagName("YOUR_ELEMENTNAME");

        if (YOURTEMPVARIABLE.Count > 0 )
        {
            doctype = YOURTEMPVARIABLE[0].InnerXml;

        }
        else
        {
            doctype = "";
        }

Answer 3

You can iterate through each and every node and see if a node exists.

doc.Load(xmlPath);
        XmlNodeList node = doc.SelectNodes("//Nodes/Node");
        foreach (XmlNode chNode in node)
        {
            try{
            if (chNode["innerNode"]==null)
                return true; //node exists
            //if ... check for any other nodes you need to
            }catch(Exception e){return false; //some node doesn't exists.}
        }

You iterate through every Node elements under Nodes (say this is root) and check to see if node named 'innerNode' (add others if you need) exists. try..catch is because I suspect this will throw popular 'object reference not set' error if the node does not exist.

Answer 4

additionally to sangam code

if (chNode["innerNode"]["innermostNode"]==null)
            return true; //node    *parentNode*/innerNode/innermostNode exists

Answer 5

Following is a simple function to check if a particular node is present or not in the xml file.

public boolean envParamExists(String xmlFilePath, String paramName){
    try{
        Document doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(new File(xmlFilePath));
        doc.getDocumentElement().normalize();
        if(doc.getElementsByTagName(paramName).getLength()>0)
            return true;
        else
            return false;
    }catch (Exception e) {
        //error handling
    }
    return false;
}

Answer 6

You can validate that and much more by using an XML schema language, like XSD.

If you mean conditionally, within code, then XPath is worth a look as well.