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C# append object to xml file using serialization

I am trying append a serialized object to an existing xml file beneath the root element, which I thought would be simple but is proving to be a little challenging.
The problem is in the AddShortcut method but I added some more code for completeness.
I believe what I need to do is:
load the file into an XmlDocument.
navigate to the node I want to append beneath (here the node name is Shortcuts).
create some type of writer and then serialize the object.
save the XmlDocument.
The trouble is in steps 2 and 3. I have tried different variations but I think using XPathNavigator somehow to find the "root" node to append under is a step in the right direction.
I have also looked at almost every question on Stack Overflow on the subject.
Any suggestions welcome. Here is my code
class XmlEngine
{
public string FullPath { get; set; } // the full path to the xmlDocument
private readonly XmlDocument xDoc;
public XmlEngine(string fullPath, string startElement, string[] rElements)
{
FullPath = fullPath;
xDoc = new XmlDocument();
CreateXmlFile(FullPath, startElement, rElements);
}
public void CreateXmlFile(string path, string startElement, string[] rElements)
{
try
{
if (!File.Exists(path))
{
// create a txt writer
XmlTextWriter wtr = new XmlTextWriter(path, System.Text.Encoding.UTF8);
// make sure the file is well formatted
wtr.Formatting = Formatting.Indented;
wtr.WriteProcessingInstruction("xml", "version='1.0' encoding='UTF-8'");
wtr.WriteStartElement(startElement);
wtr.Close();
// write the top level root elements
writeRootElements(path, rElements);
}
}
catch (Exception ex)
{
Console.WriteLine("Error: " + ex.Message);
Console.WriteLine("Could not create file: " + path);
}
}
public void AddShortcut(Shortcut s)
{
xDoc.Load(FullPath);
rootNode = xDoc.AppendChild(xDoc.CreateElement("Shortcuts"));
var serializer = new XmlSerializer(s.GetType());
using (var writer = new StreamWriter(FullPath, true))
{
XmlWriterSettings ws = new XmlWriterSettings();
ws.OmitXmlDeclaration = true;
serializer.Serialize(writer, s);
}
xDoc.Save(FullPath);
}
}

This code sample worked for me:
xml:
<?xml version="1.0" encoding="UTF-8"?>
<Launchpad>
<Shortcuts>
<Shortcut Id="1">
<Type>Folder</Type>
<FullPath>C:\SomePath</FullPath>
<Name>SomeFolderName</Name>
</Shortcut>
</Shortcuts>
</Launchpad>
Method:
public void AddShortcut(Shortcut s)
{
xDoc.Load(FullPath);
var rootNode = xDoc.GetElementsByTagName("Shortcuts")[0];
var nav = rootNode.CreateNavigator();
var emptyNamepsaces = new XmlSerializerNamespaces(new[] {
XmlQualifiedName.Empty
});
using (var writer = nav.AppendChild())
{
var serializer = new XmlSerializer(s.GetType());
writer.WriteWhitespace("");
serializer.Serialize(writer, s, emptyNamepsaces);
writer.Close();
}
xDoc.Save(FullPath);
}

load the file into an XmlDocument.
navigate to the node I want to append beneath (here the node name is Shortcuts).
create some type of writer and then serialize the object.
save the XmlDocument
So:
public void AddShortcut(Shortcut s)
{
// 1. load existing xml
xDoc.Load(FullPath);
// 2. create an XML node from object
XmlElement node = SerializeToXmlElement(s);
// 3. append that node to Shortcuts node under XML root
var shortcutsNode = xDoc.CreateElement("Shortcuts")
shortcutsNode.AppendChild(node);
xDoc.DocumentElement.AppendChild(shortcutsNode);
// 4. save changes
xDoc.Save(FullPath);
}
public static XmlElement SerializeToXmlElement(object o)
{
XmlDocument doc = new XmlDocument();
using(XmlWriter writer = doc.CreateNavigator().AppendChild())
{
new XmlSerializer(o.GetType()).Serialize(writer, o);
}
return doc.DocumentElement;
}
This post

Can not read XML document containing ampersand symbol

I am writing a program that reads a XML file with Visual C#. I have a problem reading the Xml file, because it contains invalid XML symbols, for example '&'.
I have to read the XML but I can not modify the document. How can I modify the Xml file using C#? My code so far:
private void button1_Click(object sender, EventArgs e)
{
XmlDocument doc;
doc = new XmlDocument();
doc.Load("nuevo.xml");
XmlNodeList Xpersonas = doc.GetElementsByTagName("personas");
XmlNodeList Xlista = ((XmlElement)Xpersonas[0]).GetElementsByTagName("edad");
foreach (XmlElement nodo in Xlista)
{
string edad = nodo.GetAttribute("edad");
string nombre = nodo.InnerText;
textBox1.Text = nodo.InnerXml;
}

As #EBrown suggested, one possibility would be read the file content in a string variable and replace the & symbol with the correct representation for propert XML & and then parse the XML structure. A possible solution could look like this:
var xmlContent = File.ReadAllText(#"nuevo.xml");
XmlDocument doc;
doc = new XmlDocument();
doc.LoadXml(xmlContent.Replace("&", "&"));
XmlNodeList Xpersonas = doc.GetElementsByTagName("personas");
XmlNodeList Xlista = ((XmlElement)Xpersonas[0]).GetElementsByTagName("edad");
foreach (XmlElement nodo in Xlista)
{
string edad = nodo.GetAttribute("edad");
string nombre = nodo.InnerText;
Console.WriteLine(nodo.InnerXml.Replace("&", "&"));
}
The output is:
34 & 34
If it is ok to use LINQ2XML, then the solution is even shorter, and there is no need to write the reverse(second) replace, because LINQ2XML make this for you automatically:
var xmlContent = File.ReadAllText(#"nuevo.xml");
var xmlDocument = XDocument.Parse(xmlContent.Replace("&", "&"));
var edad = xmlDocument.Root.Element("edad").Value;
Console.WriteLine(edad);
The output is the same as above.

Trying to use a remotely hosted XML file for settings

Apologies for the newbie question, I'm only on day 2 of my adventures with C#...
I'm trying to use a remotely hosted XML file to retrieve some basic settings for my program. I've managed to get it to download and parse the XML file into string variables, but I cannot work out how to make these variables available to the rest of my program.
Here is the code:
public static void getSetting()
{
try
{
XmlDocument xml = new XmlDocument();
xml.Load("http://www.domain.com/s/settings.xml");
XmlNodeList xnList = xml.SelectNodes("/Settings/Setting");
string strEnabled = ""; string strPort = "";
string strPac = ""; string strRules = ""; string strUpdateUrl = "";
foreach (XmlNode xn in xnList)
{
strEnabled = xn["Enabled"].InnerText;
strPort = xn["Port"].InnerText;
strPac = xn["Pac"].InnerText;
strRules = xn["Rules"].InnerText;
strUpdateUrl = xn["UpdateUrl"].InnerText;
}
}
catch (Exception e)
{
Console.WriteLine("Unable to download settings: " + e);
}
}
public static void useSettings()
{
//use the settings in here
}
I'd also appreciate any critique on my code as I'm still getting to grips with everything and realise that I'm probably not going about this the best way.

C# crashes on save (doc.Save(PATH);)

This program crashes on debug and highlights the "doc.Save(PATH);" at the end of the code.
I am trying to save the variables cookieScore, additionAddition, and additionMultiplier into an XML file.
I am getting information about it from here "http://visualcsharptutorials.com/net-framework/writing-xml-file"
private XmlDocument doc;
string PATH = #"C:\sample.xml";
private void saveBtn_Click(object sender, EventArgs e)
{
doc = new XmlDocument();
if (!System.IO.File.Exists(PATH))
{
XmlDeclaration declaration = doc.CreateXmlDeclaration("1.0", "UTF-8", "yes");
XmlComment comment = doc.CreateComment("This is saved game data");
XmlElement root = doc.CreateElement("data");
XmlElement data = doc.CreateElement("data");
XmlAttribute addition = doc.CreateAttribute("addition");
XmlElement additionNumber = doc.CreateElement("additionNumber");
XmlElement multiplicationNumber = doc.CreateElement("multiplicationNumber");
XmlElement cookieSave = doc.CreateElement("cookieSave");
addition.Value = "addition";
additionNumber.InnerText = additionAddition.ToString();
multiplicationNumber.InnerText = additionMultiplier.ToString();
cookieSave.InnerText = cookieScore.ToString();
doc.AppendChild(declaration);
doc.AppendChild(comment);
doc.AppendChild(root);
root.AppendChild(data);
data.Attributes.Append(addition);
data.AppendChild(cookieSave);
data.AppendChild(additionNumber);
data.AppendChild(multiplicationNumber);
doc.Save(PATH);
}
else
{
}

My guess is you're getting an access related exception because you're trying to write to the root of your C drive. Try writing to your desktop instead:
string PATH = #"C:\Users\[yourusername]\Desktop\sample.xml";
Another option would be to try to run your EXE as admin. If it works, then you know that's your problem.

c# winforms Form Load ComboBox DropDownList get value from XML file

XML File:
<?xml version="1.0" encoding="utf-16"?>
<XMLFILE>
<Active>0</Active>
<Hits_Method>1</Hits_Method>
</XMLFILE>
What i'm trying to do is on Form1_Load get the value of ComboBox4 from XML File (Hits_Method) and when the program start to show me the value. i try something like this but didn't work out
// ------------------- StartUP Load
private void Form1_Load(object sender, EventArgs e)
{
// --------------- Read XML File / Data: Settings_Ads_General
String xmlfile = "Settings_General.xml";
XmlTextReader xreader = new XmlTextReader(xmlfile);
string comboBox4Value = xreader.GetAttribute("Hits_Method");
comboBox4.SelectedIndex = comboBox4Value;
}

Try this instead:
private void Form1_Load(object sender, EventArgs e)
{
// --------------- Read XML File / Data: Settings_Ads_General
String xmlfile = "Settings_General.xml";
XmlDocument doc = new XmlDocument();
doc.Load(xmlfile);
string comboBox4Value = doc.SelectSingleNode("XMLFILE/Hits_Method").InnerText;
comboBox4.SelectedIndex = Convert.ToInt32(comboBox4Value);
}
The SelectSingleNode method extracts data based on an XPath expression. And "XMLFILE/Hits_Method" is the XPath that leads to your value.

I will use XmlDocument and XmlNode classes.
{
String sPath = "file.xml"
XmlDocument doc = new XmlDocument();
doc.Load(sPath)
XmlNode node = doc.SelectSingleNode("XMLFILE/Hits_Method");
if (node != null)
comboBox4.SelectedIndex = node.InnerText;
}