Question

First of all: What I need to achieve is write an Xml document Header, then take some elements out of an existing Xml file and put them into my document Header.

Finally I need to parse some objects into the same file.
The resulting file has to match a specific scheme as it should be imported by a program.

So far I hope it’s understandable.

My problem with that is:

I’ve written my document’s Header and extracted the elements of the second document.
But I can’t manage to write them into my Header file, without getting several Errors when trying to load them again.

Like I stated on top: I need exactly the same tags that I’ve extracted from that second file, without having c# putting in some extras like the declaration tag.

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As requested in the “How to Ask” Page I’m going to try to recapitulate all I’ve tried to make this work.

So now for my history of failures 😉
The code below is the one I ended up with after 2 days of trying. I tried some before, but this one is probably the “most” working one:

   XElement rootElement = XElement.Load(@filepath);                

        FileStream fs = new FileStream(@Savepath, FileMode.Append);                              


        IEnumerable<XElement> elements = rootElement.Descendants("Extract1");                    
        foreach (XElement item in elements)
        {
            Console.WriteLine(item);
            item.Save(fs); 
        }                                                                                    


        IEnumerable<XElement> elements2 = rootElement.Descendants("Extract2"); 
        foreach (XElement item in elements2)
        {
            Console.WriteLine(item);
            item.Save(fs);                                                                                       

        }
        fs.Close();

Console Output reads like this:

 <Extract1>
       <childnodes />
 </Extract1>
 <Extract2>
   <childnodes />
 </Extract2>

And that’s exactly what I want in my file, so it’s not like I selected the wrong nodes.
But by saving into the file a magical declaration tag appears, and the Xml looks like the one below.

<?xml version="1.0" encoding="UTF-8"?> 
<Extract1>
    <childnodes />
</Extract1><?xml version="1.0" encoding="UTF-8"?> 
<Extract2>
    <childnodes />
</Extract2>

So I can’t read the files in again.

I tried with

XmlWriterSettings settings = new XmlWriterSettings();
settings.OmitXmlDeclaration = true;

also. That kills the declaration tag, but I still can’t read the file because now
this section “scores” an error.

<Extract1>
    <childnodes />
</Extract1><Extract2>

The last thing I tried is writing the extracted items in a List listX and serialize them with the code below

XmlSerializer serializer = new XmlSerializer(typeof(List<XElement>));
            TextWriter textWriter = new StreamWriter(@savepath);
            serializer.Serialize(textWriter, listX);
            textWriter.Close();

but now I get these

<ArrayOfXElement xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
 xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<XElement>

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To summarize my problem: is there any way to read these Nodes out and “paste” them into a different file, without adding extra tags?

By the way, I thought of keeping the original Xml file and just deleting all the Nodes I don’t want, but first that might take a long time as these are pretty big Xml files, and second, they are partially generated automatically so I don’t have each Name.

Answer 1

When you write (Save()) an XElement, it assumes you want to write a complete XML document so it adds the tag.

The best solution would probably be to add them to an XDocument and save it all at once when finished.

But a short solution, minimal change form your current code:

Console.WriteLine(item);
//item.Save(fs); 
fs.WriteLine(item.ToString());

But you will have trouble surrounding this with a group (root) tag.

An alternative based on your listX:

var doc  = new XElement("Extracts", listX);
// add/insert/replace other elements
doc.Save(filePath);