c# How to get specific values from XML files by using Xpath

Question

I'm trying to find out how to get translated memory from tmx files (i.e. XML files).

Here is an extract of a tmx file I'm working on.

<tmx>
 <body>
  <tu tuid="1">
   <tuv xml:lang="en-US">
    <seg>Memory</seg>
   </tuv>
   <tuv xml:lang="ar">
    <seg>XXXXX</seg>
   </tuv>
  </tu>
  <tu tuid="2">
   <tuv xml:lang="en-US">
    <seg>Address</seg>
   </tuv>
   <tuv xml:lang="ar">
    <seg>yyyyy</seg>
   </tuv>
  </tu>
//
<body>
<tmx>

What I'm attempting to do is to search for a particular value inside "seg", and then get the corresponding value inside the next "seg".

In the above example, if I'm looking for

<seg>Memory<seg>

then, I need to retrieve

<seg>xxxxx<seg>

My coding is like this.

DataRow[] searchWordsArray = keyStrings.ToArray();
XmlNodeList nodelist = doc.SelectNodes("//body//tu");

for (int i = 0; i < searchWordsArray.Length; i++){
    for (int n = 0; n < nodelist.Count; n++) {

         string searchWord = searchWordsArray[i][KeyCol].ToString();
         string result = "";
         if (searchWord == nodelist[n].SelectSingleNode("/tuv[1]/seg").InnerText) {
             result = nodelist[n].SelectSingleNode("/tuv[2]/seg").InnerText;
         } else {
             result = "No match";
         }
    }
}

However, this code gets null reference exception at

if (searchWord == nodelist[n].SelectSingleNode("/tuv[1]/seg").InnerText) {

I guess my Xpath expression contains some error. I'd appreciate if you would give any insight.

Your XPath expressions are perfectly fine. They just don't select anything in XML you've provided. Check out any XPath reference or quick start (i.e. [Xpath Examples on MSDN](http://msdn.microsoft.com/en-us/library/ms256086%28v=vs.110%29.aspx) ) to confirm than tyou correctly understand difference between `/` and `//` in XPath. — Alexei Levenkov, Oct 03 '14 at 04:53
You're already in the `tu` node so don't do `/tuv[x]/...`. Use `tuv[x]/...` instead. As Alexei mentions, read up on what the `/` and `//` do. — TyCobb, Oct 03 '14 at 05:16
your xml isn't valid, the tmx and body tags don't have closing tags. If you mean the bottom two tags to be them... — Chuck Savage, Oct 03 '14 at 09:28

score 0 · Accepted Answer · answered Oct 03 '14 at 05:38

0

You need to add leading dot (.) or remove the leading slash (/) for the XPath to be recognized as relative path :

if (searchWord == nodelist[n].SelectSingleNode("./tuv[1]/seg").InnerText) {
     result = nodelist[n].SelectSingleNode("./tuv[2]/seg").InnerText;
}

or :

if (searchWord == nodelist[n].SelectSingleNode("tuv[1]/seg").InnerText) {
     result = nodelist[n].SelectSingleNode("tuv[2]/seg").InnerText;
}

answered Oct 03 '14 at 05:38

har07

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Thank you so much...I fixed it!:) – Hiroki Oct 04 '14 at 08:48

score 0 · Answer 2 · answered Oct 03 '14 at 09:30

Do you have to use XPath?

Using Linq-To-Xml

XElement root = XElement.Load(file);
var segs = root.Descendants("seg");
XElement check = null;
var resultNode = segs.FirstOrDefault(x => 
{
    if ((string)check == "Memory")
        return true;
    check = x;
    return false;
});
string result = (string)resultNode;

c# How to get specific values from XML files by using Xpath

2 Answers2