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C#: using xpath to find matching node

Posted on 2014-04-29
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Last Modified: 2016-02-18
I have the following method which loops through the <desc> node in an xml file to find if it matches the parameter "msg".
What I need to do is ,once found retrieve the <code> from the xml. How do I do that?

        static string getCode(string msg)
        {
            string filename = @"C:\temp\errors.xml";
            string xmlCode="";

            XmlDocument doc = new XmlDocument();
            doc.Load(filename);
            XmlNodeList nodes = doc.SelectNodes("/edt/ce/desc");

            foreach (XmlNode node in nodes)
            {
                if (node.InnerText.Trim().Equals(msg))
                    xmlCode = "Found";  //should be the <code> associated to the matching <desc>
                else
                    xmlCode = "Not found";

            }

            msg = xmlCode;

            return msg;
        }
            
            
This is errors.xml
<edt name="errors">
      <ce>
            <code>1111</code>
            <desc>Not here</desc>
      </ce>
      <ce>
            <code>2222</code>
            <desc>Invalid Input </desc>
      </ce>
</edt>
0
Comment
Question by:badtz7229
  • 3
  • 2
6 Comments
 
LVL 8

Expert Comment

by:deepu chandran
ID: 40031281
Hi,
Please try LINQ to SQL, Below code will work

IEnumerable<XElement> xmlDocuments = from x in XElement.Load(@"d:\deepu\sample.xml").Elements("ce")
                                             select x;

        var elements = from c in xmlDocuments
                       where
                           c.Element("desc").Value.Contains("Not")
                       select c;

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Thanks
Deepu
0
 
LVL 52

Assisted Solution

by:Carl Tawn
Carl Tawn earned 500 total points
ID: 40031410
You can achieve what you want in one step, rather than resorting to a loop:
XmlNode node = doc.SelectSingleNode("/edt/ce[desc='" + msg + "']/code");
if (node != null)
{   
      // found the correct node

     string code = node.InnerText;
}

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0
 

Author Comment

by:badtz7229
ID: 40031882
@carl
How do I trim <desc> before inserting he parameter? Bc sometimes there's a trailing spaces in the XML file and the match won't be found
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LVL 52

Accepted Solution

by:
Carl Tawn earned 500 total points
ID: 40031900
The normalize-space XPath function will trim whitespace from the start and end of the string:
XmlNode node = doc.SelectSingleNode("/edt/ce[normalize-space(desc)='" + msg + "']/code");

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0
 

Author Closing Comment

by:badtz7229
ID: 40032003
thank you, this worked successfully.
0
 

Author Comment

by:badtz7229
ID: 40032396
@carl
how do i use your solution in the event that the msg parameter contains an apostrophe?
(i.e. - Can't create Server object). This string exists in the xml
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