Processing an XML file removes comments

Question

This snippet <!--Please don't delete this--> is part of my xml file. After running this method, the resulting xml file does not contain this snippet anymore <!--Please don't delete this-->. Why is this?

Here's my method:

         XmlSerializer serializer = new XmlSerializer(typeof(Settings));
         TextWriter writer = new StreamWriter(path);
         serializer.Serialize(writer, settings);
         writer.Close();    

Answer 1

<!-- --> signifies a comment in XML. You are writing an object out to XML - objects do not have comments as they get compiled out during compilation.

That is, the Settings object (which is probably a de-serialized form of your .config XML) does not hold comments in memory after de-serializing, so they will not get serialized back either. There is nothing you can do about this behavior of the framework as there is no built in mechanism to de-serialize comments using XmlSerializer.

Answer 2

Well, this is quite obvious:

• the XmlSerializer will parse the XML file and extract all instances of Settings from it - your comment won't be part of any of those objects
• when you write those back out again, only the contents of the Settings objects is written out again

Your comment will fall through the cracks - but I don't see any way you could "save" that comment as long as you're using the XmlSerializer approach.

What you need to do is use the XmlReader / XmlWriter instead:

XmlReader reader = XmlReader.Create("yourfile.xml");
XmlWriter writer = XmlWriter.Create("your-new-file.xml");

while (reader.Read())
{
   writer.WriteNode(reader, true);
}

writer.Close();
reader.Close();

This will copy all xml nodes - including comments - to the new file.