Reading XML comments in C#

Question

I have got some XML files that contain comments above the nodes. When I am reading the file in, as part of the process I would like to get the comment out as well. I know you can write a comment to the file using XmlComment, but not sure how to read them back out.

My XML looks similar to this:

<Objects>
  <!--Comment about node-->
  <GUID-bf2401c0-ef5e-4d20-9d20-a2451a199362>
    <info job="SAVE" person="Joe" />    
    <info job="SAVE" person="Sally" />       
  </GUID-bf2401c0-ef5e-4d20-9d20-a2451a199362>
  <!--Another Comment about node-->
  <GUID-bf2401c0-ef5e-4d20-9d20-a5844113284112>
    <info job="SAVE" person="John" />    
    <info job="SAVE" person="Julie" />       
  </GUID-bf2401c0-ef5e-4d20-9d20-a5844113284112>

Important missing detail: What is the code you use to "read the file in"? — Tomalak, Jun 08 '11 at 11:28
Check [this answer](http://stackoverflow.com/questions/365794/how-do-i-use-xcomment-when-reading-in-an-xml-document/365870#365870) — marto, Jun 08 '11 at 11:34

score 17 · Accepted Answer · answered Jun 08 '11 at 11:32

17

Try this:

XmlReaderSettings readerSettings = new XmlReaderSettings();
readerSettings.IgnoreComments = false; 
using (XmlReader reader = XmlReader.Create("input.xml", readerSettings))
{
    XmlDocument myData = new XmlDocument();
    myData.Load(reader);
    // etc...
}

To read comments:

XmlReader xmlRdr = XmlReader.Create("Test.XML");
// Parse the file
while (xmlRdr.Read())
{
    switch (xmlRdr.NodeType)
    {
        case XmlNodeType.Element:
            // You may need to capture the last element to provide a context
            // for any comments you come across... so copy xmlRdr.Name, etc.
            break;
        case XmlNodeType.Comment:
            // Do something with xmlRdr.value

answered Jun 08 '11 at 11:32

Hasan Fahim

3,875
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2

false is the default value for `IgnoreComments` – V4Vendetta Jun 08 '11 at 11:33
2

@V4vend: Even so, both in this answer and in real code it is a good idea to set it explicitly. – H H Jun 08 '11 at 11:39
Worked a treat, i never realized the nodes had types like that. – beakersoft Jun 08 '11 at 14:10
What is comment is placed outside root element, in this case ? Could it be read and parsed? – mko May 03 '17 at 14:55

score 14 · Answer 2 · answered Jun 08 '11 at 11:37

14

Using System.Xml.Linq:

var doc = XElement.Load(fileName);
var comments = doc.DescendantNodes().OfType<XComment>();

foreach (XComment comment in comments)
   ...

answered Jun 08 '11 at 11:37

H H

263,252
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514

score 3 · Answer 3 · answered Jun 08 '11 at 11:28

3

They are a part of the child nodes of the containing node as all other nodes: http://msdn.microsoft.com/en-us/library/system.xml.xmlcomment.aspx

answered Jun 08 '11 at 11:28

Daniel Hilgarth

171,043
40
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score 2 · Answer 4 · edited Apr 29 '13 at 13:54

I know the question is very old, but yesterday I had the same problem. So here is my solution:

XmlReaderSettings settings = new XmlReaderSettings();
settings.IgnoreWhitespace = false;
settings.IgnoreComments = false;
XmlReaderSettings settings2 = new XmlReaderSettings();
settings2.IgnoreWhitespace = false;
settings2.IgnoreComments = false;
XmlReader xmlreaderOriginalCfg = XmlReader.Create(@"C:\...xml", settings);
XmlReader xmlreaderVerificationCfg = XmlReader.Create(@"C:\....xml", settings);

XmlDocument myData = new XmlDocument();
myData.Load(xmlreaderOriginalCfg);
XmlDocument myData2 = new XmlDocument();
myData2.Load(xmlreaderVerificationCfg);

XmlNode parentNode = myData.SelectSingleNode("/configuration/appSettings");

foreach (XmlComment comment in myData2.SelectNodes("//comment()"))
{
     XmlComment importedCom = myData.CreateComment(comment.Value);
     parentNode.AppendChild(importedCom);

     foreach (XmlNode node in myData2.DocumentElement.SelectNodes("/configuration/appSettings/add"))
     {
          XmlNode imported = myData.ImportNode(node, true);
          parentNode.AppendChild(imported);
     }
}
myData.Save(this.pathNew);

Maybe it helps somebody

score 0 · Answer 5 · answered Jun 08 '11 at 11:33

I stored your XML into a file, here is the code sample.

        XmlDocument document = new XmlDocument();
        document.Load("test.xml");
        foreach (XmlComment comment in document.SelectNodes("//comment()"))
        {
            Console.WriteLine("Comment: \"{0}\".", comment.Value);
        }

score 0 · Answer 6 · answered Jun 08 '11 at 11:42

Some sample code on how to access comments hope this helps

using System;
using System.IO;
using System.Xml;

public class Sample {

  public static void Main() {

    XmlDocument doc = new XmlDocument();
    doc.LoadXml(@"<Objects><!--Comment about node--><othernode/><!--Some more comment--></Objects>");

    XmlNode root = doc.FirstChild;
    if (root.HasChildNodes)
    {
      for (int i=0; i<root.ChildNodes.Count; i++)
      {
        if(     root.ChildNodes[i] is XmlComment)
            Console.WriteLine(root.ChildNodes[i].InnerText);
      }
    }
  }
}

Reading XML comments in C#

6 Answers6

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