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Add alias/prefix to existing XML namespace

How can I convert the following XML
<root xmlns:xyz="do/not/change" xmlns="add/alias">
<name>Test</name>
<xyz:id>100<xyz:id>
</root>
To
<abc:root xmlns:xyz="do/not/change" xmlns:abc="add/alias">
<abc:name>Test</abc:name>
<xyz:id>100<xyz:id>
</abc:root>
Using XDocument in C#
Effectively, I want to add an alias to the second namespace, and add the prefix to all elements that do not already have a prefix.
All the information I can find is how to remove or add a namespace, but nothing about how to add a prefix/alias.

It should be something like:
var xml = #"<root xmlns:xyz='do/not/change' xmlns='add/alias'>
<name>Test</name>
<xyz:id>100</xyz:id>
</root>";
var xdoc = XDocument.Parse(xml);
var xn = xdoc.Root.GetDefaultNamespace();
xdoc.Root.SetAttributeValue(XNamespace.Xmlns + "abc", xn.NamespaceName);
xdoc.Root.Attribute("xmlns").Remove();
foreach (var el in xdoc.Root.DescendantsAndSelf())
{
if (el.Name.Namespace == xn)
{
el.Name = xn + el.Name.LocalName;
}
}
Note that this code will break if there is no default namespace defined.
You can add a check like:
if (xn.NamespaceName == string.Empty) ...
Note 2: technically even attributes can have namespaces, like xyz:myattr="Hello". We are skipping this.

How to remove xmlns attribute of a node other than root in an XDocument?

Situation
I'm using XDocument to try and remove an xmlns="" attribute on the first inner node:
<Root xmlns="http://my.namespace">
<Firstelement xmlns="">
<RestOfTheDocument />
</Firstelement>
</Root>
So what I want as a result is:
<Root xmlns="http://my.namespace">
<Firstelement>
<RestOfTheDocument />
</Firstelement>
</Root>
Code
doc = XDocument.Load(XmlReader.Create(inStream));
XElement inner = doc.XPathSelectElement("/*/*[1]");
if (inner != null)
{
inner.Attribute("xmlns").Remove();
}
MemoryStream outStream = new MemoryStream();
XmlWriter writer = XmlWriter.Create(outStream);
doc.Save(writer); // <--- Exception occurs here
Problem
Upon trying to save the document, I get the following exception:
The prefix '' cannot be redefined from '' to 'http://my.namespace' within the same start element tag.
What does this even mean and what can I do to remove that pesky xmlns=""?
Notes
I do want to keep the root node's namespace
I only want that specific xmlns removed, there will be no other xmlns attributes in the document.
Update
I've tried using code inspired from answers on this question:
inner = new XElement(inner.Name.LocalName, inner.Elements());
When debugging, the xmlns attribute is gone from it but I get the same exception.

I think the code below is what you want. You need to put each element into the right namespace, and remove any xmlns='' attributes for the affected elements. The latter part is required as otherwise LINQ to XML basically tries to leave you with an element of
<!-- This would be invalid -->
<Firstelement xmlns="" xmlns="http://my.namespace">
Here's the code:
using System;
using System.Xml.Linq;
class Test
{
static void Main()
{
XDocument doc = XDocument.Load("test.xml");
// All elements with an empty namespace...
foreach (var node in doc.Root.Descendants()
.Where(n => n.Name.NamespaceName == ""))
{
// Remove the xmlns='' attribute. Note the use of
// Attributes rather than Attribute, in case the
// attribute doesn't exist (which it might not if we'd
// created the document "manually" instead of loading
// it from a file.)
node.Attributes("xmlns").Remove();
// Inherit the parent namespace instead
node.Name = node.Parent.Name.Namespace + node.Name.LocalName;
}
Console.WriteLine(doc); // Or doc.Save(...)
}
}

There is no need to 'remove' the empty xmlns attribute. The whole reason that the empty xmlns attrib is added is because the namespace of your childnodes is empty (= '') and therefore differ from your root node. Adding the same namespace to your childs as well will solve this 'side-effect'.
XNamespace xmlns = XNamespace.Get("http://my.namespace");
// wrong
var doc = new XElement(xmlns + "Root", new XElement("Firstelement"));
// gives:
<Root xmlns="http://my.namespace">
<Firstelement xmlns="" />
</Root>
// right
var doc = new XElement(xmlns + "Root", new XElement(xmlns + "Firstelement"));
// gives:
<Root xmlns="http://my.namespace">
<Firstelement />
</Root>

Deleting node from string with xml structure

I have an string parameter with xml content in it. Basically the string have an XML inside.
string S = funcThatReturnsXML (parameters);
S have the next text:
<?xml version="1.0" encoding="utf-8" ?>
<tagA>
<tagB>
<tagBB>
..
.
.
</tagBB>
.
.
</tagB>
<tagC>
..
..
.
</tagC>
</tagA>
The funcThatReturnsXML (parameters) creates an XmlDocument object but the return it as a string, I cant change this function, to much stuff works with it.
Tried to create XmlDocument objetc but the SelectSingleNode return null.
XmlDocument xmlDoc = new XmlDocument();
xmlDoc.LoadXml(S);
XmlNode root = xmlDoc.SelectSingleNode("tagB");
How can I delete from string S (not XML Object) specific node, for example <tagB>
EDIT: this is the XML I tested with:
<?xml version="1.0" ?>
- <Request xmlns:xsi="http://www.mysite.com" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
- <info xmlns="http://www.mysite.com">
<RequestTR>54</RequestTR>
<time>2013-12-22</time>
</info>
- <Parameters xmlns="http://www.mysite.com">
<id>3</id>
<name>2</name>
</Parameters>
<title>Request</title>
</Request>

Try this:
string S = funcThatReturnsXML(parameters);
var doc = XDocument.Parse(S);
var nodeToRemove = doc.Descendants("tagB");
nodeToRemove.Remove();
That will remove all nodes named "tagB" from string S which contains xml.
UPDATE 1:
Sorry, i missed to include one more line:
S = doc.ToString();
My first code above removed "tagB" from doc but didnt save it back to S variable.
UPDATE 2:
I tested with following xml which contain attribute:
<tagA attribute="value">
<tagB>
<tagBB>
</tagBB>
</tagB>
<tagC></tagC>
</tagA>
and the output of Console.WriteLine(S):
<tagA attribute="value">
<tagC></tagC>
</tagA>
UPDATE 3:
Given your updated xml format, I know why my previous code didn't work for you. That was because your xml have namespace (xmlns) declared. The solution is to use LocalName when searching for the node to be removed, that will search for node name while ignoring its namespace. The follwoing example shows how to remove all "info" node:
var doc = XDocument.Parse(S);
var nodeToRemove = doc.Descendants().Where(o => o.Name.LocalName == "info");
nodeToRemove.Remove();
S = doc.ToString();

If you can determine the particular outer element to remove from the returned XML, you could use LINQ to XML:
var returnedXml = funcThatReturnsXML(parameters);
var xmlElementToRemove = funcThatReturnsOuterElement(returnedXml);
var xelement = XElement.Load("XmlDoc.txt");
xelement.Elements().Where(e => e.Name == xmlElementToRemove).Remove();
For example:
using System.Linq;
using System.Xml.Linq;
class Program
{
static void Main(string[] args)
{
// pretend this is the funThatReturnsXML return value
var returnedXml = "<tagB><tagBB></tagBB></tagB>";
// get the outer XML element name
var xmlElementToRemove = GetOuterXmlElement(returnedXml);
// load XML from where ever
var xelement = XElement.Load("XmlDoc.txt");
// remove the outer element and all subsequent elements
xelement.Elements().Where(e => e.Name == xmlElementToRemove).Remove();
}
static string GetOuterXmlElement(string xml)
{
var index = xml.IndexOf('>');
return xml.Substring(1, index - 1);
}
}
Note that the above is a "greedy" removal method, if there is more than once element with the name returned via the GetOuterXmlElemet method they will all be removed. If you want a specific instance to be removed then you will require something more sophisticated.

Building on your edit:
XmlDocument xmlDoc = new XmlDocument();
xmlDoc.LoadXml(S);
var nodeA = xmlDoc.SelectSingleNode("/tagA");
var nodeB = nodeA.SelectSingleNode("tagB");
nodeA.RemoveChild(nodeB);
To remove (possibly) multiple tagB nodes in unknown positions, you may try:
var bees = xmlDoc.SelectNodes("//tagB");
foreach (XmlNode bee in bees) {
var parent = bee.ParentNode;
parent.RemoveChild(bee);
}

How to Remove Root Element in C#/

I'm new to XML & C#.
I want to remove root element without deleting child element.
XML file is strudctured as below.
<?xml version="1.0" encoding="UTF-8"?>
<dataroot generated="2013-07-06T20:26:48" xmlns:od="urn:schemas-microsoft-com:officedata">
<MetaDataSection>
<Name>KR04</Name>
<XMLCreationDate>02.05.2013 9:52:41 </XMLCreationDate>
<Address>AUTOMATIC</Address>
<Age>22</Age>
</MetaDataSection>
</dataroot>
I want to root element "dataroot", so it should look like below.
<?xml version="1.0" encoding="UTF-8"?>
<MetaDataSection>
<Name>KR04</Name>
<XMLCreationDate>02.05.2013 9:52:41 </XMLCreationDate>
<Address>AUTOMATIC</Address>
<Age>22</Age>
</MetaDataSection>
Deleting child elements look like easy, but I don't know how to delete root element only.
Below is the code I've tried so far.
XmlDocument xmlFile = new XmlDocument();
xmlFile.Load("path to xml");
XmlNodeList nodes = xmlFile.SelectNodes("//dataroot");
foreach (XmlElement element in nodes)
{
element.RemoveAll();
}
Is there a way to remove root element only? without deleting child elements?
Thank you in advnace.

Rather than trying to actually remove the root element from an existing object, it looks like the underlying aim is to save (or at least access) the first child element of the root element.
The simplest way to do this is with LINQ to XML - something like this:
XDocument input = XDocument.Load("input.xml");
XElement firstChild = input.Root.Elements().First();
XDocument output = new XDocument(new XDeclaration("1.0", "utf-8", "yes"),
firstChild);
output.Save("output.xml");
Or if you don't need the XML declaration:
XDocument input = XDocument.Load("input.xml");
XElement firstChild = input.Root.Elements().First();
firstChild.Save("output.xml");

if you need to do in c# coding means
Solution
foreach (XElement item in Element.Descendants("dataroot").ToList())
{
item.ReplaceWith(item.Nodes());
}

XPath and attributes

I'm trying to traverse an XML document and select certain node attributes. The XML is dynamically generated.
<?xml version="1.0" encoding="ISO-8859-1"?>
<streams>
<stream>
<title>+23 (Panama)</title>
<info resolution="768x420" bitrate="1000kbps"/> ----- Need These
<swfUrl>http://www.freeetv.com/script/mediaplayer/player.swf</swfUrl>
<link>rtmp://200.75.216.156/live/</link>
<pageUrl>http://www.freeetv.com/</pageUrl>
<playpath>livestream</playpath>
<language>Music</language>
<advanced></advanced>
</stream>
</streams>
The code that I'm trying to use with zero luck and Visual Studio saying "No you're wrong. Try 600 more times" is
xDoc.Load("http://127.0.0.1/www/xml.php");
XmlNodeList nodes = xDoc.SelectNodes("/streams/stream");
foreach (XmlNode xn in nodes)
{
ListViewItem lvi = listView1.Items.Add(xn["title"].InnerText);
lvi.SubItems.Add(xn["swfUrl"].InnerText);
lvi.SubItems.Add(xn["link"].InnerText);
lvi.SubItems.Add(xn["pageUrl"].InnerText);
lvi.SubItems.Add(xn["playpath"].InnerText);
lvi.SubItems.Add(xn["language"].InnerText);
lvi.SubItems.Add(xn["advanced"].InnerText);
lvi.SubItems.Add(xn["//info/#resolution"].Value);
}
Please tell me oh wise ones what am I doing wrong?

If you want to select node's attribute using XPath you should use SelectSingleNode method, e.g.:
xn.SelectSingleNode("info/#resolution").Value

To select resolution attribute of your last node you need to use:
xn["info"].Attributes["resolution"].Value
Alternatively, you can try LINQ to XML for the same results (I find its API easier to use):
var doc = XDocument.Parse("http://127.0.0.1/www/xml.php");
foreach (var d in doc.Descendants("stream"))
{
ListViewItem lvi = listView1.Items.Add(d.Element("title").Value);
lvi.SubItems.Add(d.Element("swfUrl").Value);
// ...
vi.SubItems.Add(d.Element("info").Attribute("resolution").Value);
}

Here is an example of LINQ to XML to extract attributes from the entire document of a particular attribute name OR list of attribute names.
var xml = XElement.Parse("http://127.0.0.1/www/xml.php");
// find all attributes of a given name
var attributes = xml
.Descendants()
.Attributes("AttributeName")
// find all attributes of multiple names
var attributes = xml
.Descendants()
.Attributes()
.Where(a => ListOfAttribNames.Contains(a.Name.LocalName))

Replace:
lvi.SubItems.Add(xn["//info/#resolution"].Value);
with:
lvi.SubItems.Add(xn.SelectSingleNode("info/#resolution").Value);