Xpath | Gokul's Blog

April 2, 2010
by gokulrajad Leave a comment

Get Xpath Value

 string[] fileEntries = Directory.GetFiles(txtFolderName.Text);

string sXpathQuery = @"//ns0:MyXpath"; ;
string xmlNameSpacePrefix = "ns0"
                        , xmlNameSpace = @"http://MyNamespace/";

    foreach (string fileName in fileEntries)
    {
        try
        {
                // Load the document and set the root element.
                XmlDocument xdoc = new XmlDocument();
                xdoc.Load(fileName);
                XmlNode root = xdoc.DocumentElement;

                XmlNodeList nodeList;
                if (!string.IsNullOrEmpty(xmlNameSpace))
                {
                    // Add the namespace.
                    XmlNamespaceManager nsmgr = new XmlNamespaceManager(xdoc.NameTable);
                    nsmgr.AddNamespace(xmlNameSpacePrefix, xmlNameSpace);
                    nodeList = root.SelectNodes(sXpathQuery, nsmgr);
                }
                else
                {
                    nodeList = root.SelectNodes(sXpathQuery);
                }

                foreach (XmlNode node in nodeList)
                {
                    //if(node.LastChild.InnerText  == "ABCD")
                        txtStatus.Text = txtStatus.Text + node.LastChild.InnerText + ", " 
                                        + fileName + Environment.NewLine;
                }
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.StackTrace.ToString());
            throw ex;
        }
    }

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, “Courier New”, courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, “Courier New”, courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

January 11, 2010
by gokulrajad Leave a comment

Get Xpath Value from XMLTextReader

The below code is used to get Xpathvalue from a xmltextreader object. 
Thanks to Naresh(my-colleague) for this quick snippet.

      void TestOne(XmlTextReader reader,string xpathQuery)
        {
            System.Console.WriteLine("TestOne");
            XPathDocument xdoc = new XPathDocument(reader);
            XPathNavigator nav = xdoc.CreateNavigator();
            XPathNodeIterator nodeItor = nav.Select(xpathQuery);
             //"STUFF/TYPE1/CENSUS[@COUNTRY='USA' and @YEAR='1930']/PAGE");
            nodeItor.MoveNext();
            TraverseSiblings(nodeItor);
            System.Console.WriteLine();
        }

         void TraverseSiblings(XPathNodeIterator nodeItor)
        {
            XPathNodeIterator igor = nodeItor.Clone();
            PrintNode(igor.Current);
            igor.Current.MoveToNext();
            bool more = false;
            do
            {
                PrintNode(igor.Current);
                more = igor.Current.MoveToNext();
            } while (more);
        }

         void PrintNode(XPathNavigator nav)
        {
            System.Console.WriteLine(nav.Name + ":" + nav.Value +
                " Type : " + nav.NodeType.ToString());
        }

One more code sample which I have implemented

            XPathNavigator nav;
            XPathDocument doc;
            XPathNodeIterator NodeIter;
            String rv=string.Empty;

            doc = new XPathDocument(reader);
            nav = doc.CreateNavigator();
            //sXpathQuery = @"//EmployeeName/attribute::SourceID";
            System.Diagnostics.Debug.WriteLine("Source Id:  {0}", nav.Evaluate(sXpathQuery).ToString());
                NodeIter = nav.Select(sXpathQuery);
                while (NodeIter.MoveNext())
                {
                    rv=NodeIter.Current.InnerXml;

                    System.Diagnostics.Debug.WriteLine("------------item start------------------");
                    System.Diagnostics.Debug.WriteLine(rv);
                    System.Diagnostics.Debug.WriteLine("-------------item end-------------------");
                    //Console.WriteLine(NodeIter.Current.Value);
                    //Console.WriteLine("////////////////////////////////");

                    if (!string.IsNullOrEmpty(rv))
                        break;
                }
Other interesting links

http://www1.cs.columbia.edu/~lok/csharp/refdocs/System.Xml.XPath/types/XPathDocument.html

http://xhinker.com/CategoryView,category,XMLXPath.aspx

May 14, 2008
by gokulrajad Leave a comment

Xpath: Check an element Exists while using Xpath Query

sMyString= xpath(inputMessage, "string(//*[local-name()=’MyElementName’])");

You can use System.String.IsNullOrEmpty(sMyString) to check if the value is present.

April 8, 2008
by gokulrajad Leave a comment

Xpath: Get Distinct node values in Xpath

Xpath to select nodes with distinct attribute value

Getting a list of nodes with distinct value in an attribute using xpath . The key is to use the preceding keyword.

The Xpath query will return only the distinct nodes. I used sketchpath to learn/arrive at the this example Xpath Query. This is is similar to the Regex editor we use for Regular Expressions.

Example Xpath Query: //Schedule[not(./@SourceID=preceding::Schedule/@SourceID)]

Sample Xml:

<ns0:Listings xmlns:ns0="http://myTest.Namespace">
    <Programs>
        <Program ProgramTitle="Program - 1025">
            <Schedules xmlns:ns0="http://Mytest.Namespace2">
                <Schedule SourceID="123"></Schedule>
            </Schedules>
        </Program>
        <Program ProgramTitle="Program - 1225">
            <Schedules xmlns:ns0="http://Mytest.Namespace2">
                <Schedule SourceID="123" ></Schedule>
            </Schedules>
        </Program>
        <Program ProgramTitle="Program - 1405">
            <Schedules xmlns:ns0="http://Mytest.Namespace2">
                <Schedule SourceID="124"></Schedule>
            </Schedules>
        </Program>
        <Program ProgramTitle="Program - 1505">
            <Schedules xmlns:ns0="http://Mytest.Namespace2">
                <Schedule SourceID="145"></Schedule>
                <Schedule SourceID="146"></Schedule>
            </Schedules>
        </Program>
        <Program ProgramTitle="Program - 2005">
            <Schedules xmlns:ns0="http://Mytest.Namespace2">
                <Schedule SourceID="225"></Schedule>
            </Schedules>
        </Program>
    </Programs>
</ns0:Listings>

Tool: Sketchpath Link & download sketchpath utility from my blog

Another good tool is xmlviewer from bizbert.com. From my blog

Some gotchas and refernce links for Xpath:

http://www.sabratech.co.uk/blogs/yossidahan/2006/10/xpath-to-select-nodes-with-distinct.html

http://www.sabratech.co.uk/blogs/yossidahan/2006/09/returning-text-only-from-xpath-in.html

Ever got this error <element xmlns=''> was not expected 
Actually, it took quite some time before I discovered what was wrong with my XPath. 
My expression was: emailId = xpath(MyMessage, "/*[local-name.........."); 
and I needed to change it to emailId = xpath(MyMessage, "string(/*[local-name..........)");
Added the string to my xpath query.

Disclaimer: I host these tools on my site for quick access. As I had experience with some other tools, either the sites go 
missing or down for maintenance when needed. So please goto the respective sites for download as mentioned. If you don't get 
them, get it from here.