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C# - How to remove xmlns from XElement

How can I remove the xmlns namespace from a XElement?
I tried: attributes.remove, xElement.Name.NameSpace.Remove(0), etc, etc. No success.
My xml:
<event xmlns="http://www.blablabla.com/bla" version="1.00">
<retEvent version="1.00">
</retEvent>
</event>
How can I accomplish this?

#octaviocc's answer did not work for me because xelement.Attributes() was empty, it wasn't returning the namespace as an attribute.
The following will remove the declaration in your case:
element.Name = element.Name.LocalName;
If you want to do it recursively for your element and all child elements use the following:
private static void RemoveAllNamespaces(XElement element)
{
element.Name = element.Name.LocalName;
foreach (var node in element.DescendantNodes())
{
var xElement = node as XElement;
if (xElement != null)
{
RemoveAllNamespaces(xElement);
}
}
}

I'd like to expand upon the existing answers. Specifically, I'd like to refer to a common use-case for removing namespaces from an XElement, which is: to be able to use Linq queries in the usual way.
When a tag contains a namespace, one has to use this namespace as an XNamespace on every Linq query (as explained in this answer), so that with the OP's xml, it would be:
XNamespace ns = "http://www.blablabla.com/bla";
var element = xelement.Descendants(ns + "retEvent")).Single();
But usually, we don't want to use this namespace every time. So we need to remove it.
Now, #octaviocc's suggestion does remove the namespace attribute from a given element. However, the element name still contains that namespace, so that the usual Linq queries won't work.
Console.WriteLine(xelement.Attributes().Count()); // prints 1
xelement.Attributes().Where( e => e.IsNamespaceDeclaration).Remove();
Console.WriteLine(xelement.Attributes().Count()); // prints 0
Console.WriteLine(xelement.Name.Namespace); // prints "http://www.blablabla.com/bla"
XNamespace ns = "http://www.blablabla.com/bla";
var element1 = xelement.Descendants(ns + "retEvent")).SingleOrDefault(); // works
var element2 = xelement.Descendants("retEvent")).SingleOrDefault(); // returns null
Thus, we need to use #Sam Shiles suggestion, but it can be simplified (no need for recursion):
private static void RemoveAllNamespaces(XElement xElement)
{
foreach (var node in xElement.DescendantsAndSelf())
{
node.Name = node.Name.LocalName;
}
}
And if one needs to use an XDocument:
private static void RemoveAllNamespaces(XDocument xDoc)
{
foreach (var node in xDoc.Root.DescendantsAndSelf())
{
node.Name = node.Name.LocalName;
}
}
And now it works:
var element = xelement.Descendants("retEvent")).SingleOrDefault();

You could use IsNamespaceDeclaration to detect which attribute is a namespace
xelement.Attributes()
.Where( e => e.IsNamespaceDeclaration)
.Remove();

Extracting XML Child Elements Where the Parents are in a Defaulted Namespace

I have the below XML and I've been trying to extract the FirstName, LastName and OtherName for a while now I'm running into all sort of problems.
<OmdCds xmlns="cds"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:cdsd="cds_dt"
xsi:schemaLocation="cds ontariomd_cds.xsd">
<PatientRecord>
<Demographics>
<Names>
<cdsd:LegalName namePurpose="L">
<cdsd:FirstName>
<cdsd:Part>SARAH</cdsd:Part>
<cdsd:PartType>GIV</cdsd:PartType>
<cdsd:PartQualifier>BR</cdsd:PartQualifier>
</cdsd:FirstName>
<cdsd:LastName>
<cdsd:Part>GOMEZ</cdsd:Part>
<cdsd:PartType>FAMC</cdsd:PartType>
<cdsd:PartQualifier>BR</cdsd:PartQualifier>
</cdsd:LastName>
<cdsd:OtherName>
<cdsd:Part>GABRIELA</cdsd:Part>
<cdsd:PartType>GIV</cdsd:PartType>
<cdsd:PartQualifier>BR</PartQualifier>
I currently trying to extract with the below c# code but still can't extract the above data. I'm getting a nullreferenceexception.
XmlDocument doc = new XmlDocument();
doc.Load(folder + "\\" + o.ToString());
XmlNamespaceManager namespaceManager = new XmlNamespaceManager(doc.NameTable);
namespaceManager.AddNamespace("cdsd", "http://www.w3.org/2001/XMLSchema-instance");
XmlNode firstName = doc.DocumentElement.SelectSingleNode("/PatientRecord/Demographics/Names/cdsd:LegalName/cdsd:FirstName/cdsd:Part", namespaceManager);
string fName = firstName.InnerText;
MessageBox.Show(fName);
I can see in the local watch item under doc.DocumentElement, all the InnerXML and InnerText. The InnerXML look something like this...
<PatientRecord xmlns=\"cds\"><Demographics><Names><cdsd:LegalName namePurpose=\"L\" xmlns:cdsd=\"cds_dt\"><cdsd:FirstName><cdsd:Part>SARAH</cdsd:Part><cdsd:PartType>GIV</cdsd:PartType><cdsd:PartQualifier>BR</cdsd:PartQualifier></cdsd:FirstName>

You have 3 namespace definitions in the document:
cds - as a default namespace
http://www.w3.org/2001/XMLSchema-instance- with the xsi prefix
cds_dt - with the cdsd prefix
I am wondering that you don't get an error message, because cds and cds_dt are no URIs and namspaces need to be URIs.
If you try to understand an element name you need to replaces the prefix with the actual namespace.
<PatientRecord> reads as {cds}:PatientRecord
<cdsd:LegalName> reads as {cds_dt}:LegalName
Now in XPath 1.0 the same happens with registered namespaces. But XPath does not have a default namespace. So elements without one are not expanded with a default namespace.
You need to register namespace prefixes on the namespace manager. The prefix does not need to be the same as in the document.
namespaceManager.AddNamespace("cdsd", "cds_dt");
namespaceManager.AddNamespace("cds", "cds");
Now you can use the registered namespaces in XPath:
doc.DocumentElement.SelectSingleNode(
"cds:PatientRecord/cds:Demographics/cds:Names/cdsd:LegalName/cdsd:FirstName/cdsd:Part",
namespaceManager
);
If the first character of an XPath expression is a slash the expression is relative to the document, otherwise to the current context node. You call SelectSingleNode() on the doc.DocumentElement - the OmdCds element node. PatientRecord is a child node, so you can start with it or use . for the current context node.

PatientRecord, Demographics and Names are in the cds namespace. This is because of the default namespace declaration on the OmdCds element (xmlns="cds"). The others are in the cdsd namespace, not xsi. You'll have to add them and use them in the XPATH:
namespaceManager.AddNamespace("cdsd", "cdsd");
namespaceManager.AddNamespace("cds", "cds");
XmlNode firstName = doc.DocumentElement.SelectSingleNode(
"/cds:PatientRecord/cds:Demographics/cds:Names/cdsd:LegalName/cdsd:FirstName/cdsd:Part",
namespaceManager);
BTW, you're getting a NullReferenceException because you're making the false assumption that your query will always return a node. You are now seeing what happens when it does not return a node. Always check for null whenever it's possible that a query returns no value.

Instead XmlDocument class you can use Linq to XML, is easy. You need using the System.Xml.Linq namspace, for example:
XDocument xdoc = XDocument.Load("path");
IEnumerable<XElement> nodes = (from p in xdoc.Descendants()
where p.Name.LocalName == "FirstName"
select p).Elements();
foreach (XElement nodeFirstName in nodes)
{
foreach (XElement parts in nodeFirstName.Elements())
{
string strExtracted = parts.Name.LocalName + " " + parts.Value;
}
}
The LocalName property is used beacuse elements have a prefix "cdsd"

LINQ to XML - How to fix default namespace in the root element

Consider generating the following XML structure, which has 2 prefixed namespaces:
XNamespace ns1 = "http://www.namespace.org/ns1";
const string prefix1 = "w1";
XNamespace ns2 = "http://www.namespace.org/ns2";
const string prefix2 = "w2";
var root =
new XElement(ns1 + "root",
new XElement(ns1 + "E1"
, new XAttribute(ns1 + "attr1", "value1")
, new XAttribute(ns2 + "attr2", "value2"))
, new XAttribute(XNamespace.Xmlns + prefix2, ns2)
, new XAttribute(XNamespace.Xmlns + prefix1, ns1)
);
It generates the following XML result (which is fine):
<w1:root xmlns:w2="http://www.namespace.org/ns2" xmlns:w1="http://www.namespace.org/ns1">
<w1:E1 w1:attr1="value1" w2:attr2="value2" />
</w1:root>
The problem arises when I try to change ns1 from a prefixed namespace to a default namespace by commenting out its XML declaration, as in:
var root =
new XElement(ns1 + "root",
new XElement(ns1 + "E1"
, new XAttribute(ns1 + "attr1", "value1")
, new XAttribute(ns2 + "attr2", "value2"))
, new XAttribute(XNamespace.Xmlns + prefix2, ns2)
//, new XAttribute(XNamespace.Xmlns + prefix1, ns1)
);
which produces:
<root xmlns:w2="http://www.namespace.org/ns2" xmlns="http://www.namespace.org/ns1">
<E1 p3:attr1="value1" w2:attr2="value2" xmlns:p3="http://www.namespace.org/ns1" />
</root>
Note the duplicate namespace definitions in root and E1 and attributes prefixed as p3 under E1. How can I avoid this from happening? How can I force declaration of default namespace in the root element?
Related Questions
I studied this question: How to set the default XML namespace for an XDocument
But the proposed answer replaces namespace for elements without any namespace defined. In my samples the elements and attributes already have their namespaces correctly set.
What I have tried
Based on too many trial and errors, it seems to me that attributes which are not directly under the root node, where the attribute and its direct parent element both have the same namespace as the default namespace; the namespace for the attribute needs to be removed!!!
Based on this I defined the following extension method which traverses all the elements of the resulting XML and performs the above. In all my samples thus far this extension method fixed the problem successfully, but it doesn't necessarily mean that somebody can't produce a failing example for it:
public static void FixDefaultXmlNamespace(this XElement xelem, XNamespace ns)
{
if(xelem.Parent != null && xelem.Name.Namespace == ns)
{
if(xelem.Attributes().Any(x => x.Name.Namespace == ns))
{
var attrs = xelem.Attributes().ToArray();
for (int i = 0; i < attrs.Length; i++)
{
var attr = attrs[i];
if (attr.Name.Namespace == ns)
{
attrs[i] = new XAttribute(attr.Name.LocalName, attr.Value);
}
}
xelem.ReplaceAttributes(attrs);
}
}
foreach (var elem in xelem.Elements())
elem.FixDefaultXmlNamespace(ns);
}
This extension method produces the following XML for our question, which is what I desire:
<root xmlns:w2="http://www.namespace.org/ns2" xmlns="http://www.namespace.org/ns1">
<E1 attr1="value1" w2:attr2="value2" />
</root>
However I don't like this solution, mainly because it is expensive. I feel I'm missing a small setting somewhere. Any ideas?

Quoting from here:
An attribute is not considered a child of its parent element. An attribute never inherits the namespace of its parent element. For that reason an attribute is only in a namespace if it has a proper namespace prefix. An attribute can never be in a default namespace.
and here:
A default namespace declaration applies to all unprefixed element names within its scope. Default namespace declarations do not apply directly to attribute names; the interpretation of unprefixed attributes is determined by the element on which they appear.
It seems that this odd behavior of LINQ-to-XML is rooted in standards. Therefore whenever adding a new attribute its namespace must be compared against the parents' default namespace which is active in its scope. I use this extension method for adding attributes:
public static XAttribute AddAttributeNamespaceSafe(this XElement parent,
XName attrName, string attrValue, XNamespace documentDefaultNamespace)
{
if (newAttrName.Namespace == documentDefaultNamespace)
attrName = attrName.LocalName;
var newAttr = new XAttribute(attrName, attrValue);
parent.Add(newAttr);
return newAttr;
}
And use this extension method for retrieving attributes:
public static XAttribute GetAttributeNamespaceSafe(this XElement parent,
XName attrName, XNamespace documentDefaultNamespace)
{
if (attrName.Namespace == documentDefaultNamespace)
attrName = attrName.LocalName;
return parent.Attribute(attrName);
}
Alternatively, if you have the XML structure at hand and want to fix the namespaces already added to attributes, use the following extension method to fix this (which is slightly different from that outlined in the question):
public static void FixDefaultXmlNamespace(this XElement xelem,
XNamespace documentDefaultNamespace)
{
if (xelem.Attributes().Any(x => x.Name.Namespace == documentDefaultNamespace))
{
var attrs = xelem.Attributes().ToArray();
for (int i = 0; i < attrs.Length; i++)
{
var attr = attrs[i];
if (attr.Name.Namespace == documentDefaultNamespace)
{
attrs[i] = new XAttribute(attr.Name.LocalName, attr.Value);
}
}
xelem.ReplaceAttributes(attrs);
}
foreach (var elem in xelem.Elements())
elem.FixDefaultXmlNamespace(documentDefaultNamespace);
}
Note that you won't need to apply the above method, if you have used the first two methods upon adding and retrieving attributes.

I have found something for you, from the C# in a Nutshell book:
You can assign namespaces to attributes too. The main difference is that it always
requires a prefix. For instance:
<customer xmlns:nut="OReilly.Nutshell.CSharp" nut:id="123" />
Another difference is that an unqualified attribute always has an empty namespace:
it never inherits a default namespace from a parent element.
So given your desired output i have made a simple check.
var xml = #"<root xmlns:w2=""http://www.namespace.org/ns2"" xmlns=""http://www.namespace.org/ns1"">
<E1 attr1=""value1"" w2:attr2=""value2"" />
</root>";
var dom = XElement.Parse(xml);
var e1 = dom.Element(ns1 + "E1");
var attr2 = e1.Attribute(ns2 + "attr2");
var attr1 = e1.Attribute(ns1 + "attr1");
// attr1 is null !
var attrNoNS = e1.Attribute("attr1");
// attrNoNS is not null
So in short attr1 does not have default namespace, but has an empty namespace.
Is this you want? If yes, just create you attr1 without namespace...
new XAttribute("attr1", "value1")

How to cast XPathEvalute when it can be XElement or XAttribute?

So I have this code:
List<PriceDetail> prices =
(from item in xmlDoc.Descendants(shop.DescendantXName)
select new PriceDetail
{
Price = GetPrice(item.Element(shop.PriceXPath).Value),
GameVersion = GetGameVersion(((IEnumerable)item.XPathEvaluate(shop.TitleXPath)).Cast<XAttribute>().First<XAttribute>().Value, item.Element(shop.PlatformXPath).Value),
Shop = shop,
Link = item.Element(shop.LinkXPath).Value,
InStock = InStock(item.Element(shop.InStockXPath).Value)
}).ToList<PriceDetail>();
The problem I have is this code:
((IEnumerable)item.XPathEvaluate(shop.TitleXPath)).Cast<XAttribute>().First<XAttribute>().Value
Sometimes the object from XPathEvaluate could be XElement and then the casting doesn't work. So what I need is a Cast that works with both XAttribute and XElement.
Any suggestion?

Change your XPath expression (shop.TitleXPath) from:
someXPathExpression
to:
string(someXPathExpression)
Then you can simplify the code to just:
string result = item.XPathEvaluate(shop.TitleXPath) as string;
Complete working example:
using System;
using System.IO;
using System.Xml.Linq;
using System.Xml.XPath;
class TestXPath
{
static void Main(string[] args)
{
string xml1 =
#"<t>
<a b='attribute value'/>
<c>
<b>element value</b>
</c>
<e b='attribute value'/>
</t>";
string xml2 =
#"<t>
<c>
<b>element value</b>
</c>
<e b='attribute value'/>
</t>";
TextReader sr = new StringReader(xml1);
XDocument xdoc = XDocument.Load(sr, LoadOptions.None);
string result1 = xdoc.XPathEvaluate("string(/*/*/#b | /*/*/b)") as string;
TextReader sr2 = new StringReader(xml2);
XDocument xdoc2 = XDocument.Load(sr2, LoadOptions.None);
string result2 = xdoc2.XPathEvaluate("string(/*/*/#b | /*/*/b)") as string;
Console.WriteLine(result1);
Console.WriteLine(result2);
}
}
When this program is executed, the same XPath expression is applied on two different XML documents and, regardless of the fact that the argument to string() is an attribute the first time and is an element on the second, we get the correct results -- written to the Console:
attribute value
element value

Dimitre's solution returns empty string if the element is not found; we can't distinguish it from actual empty value. So I had to make this extension method that handles multiple results by XPath query and returns empty enumeration if nothing is found:
public static IEnumerable<string> GetXPathValues(this XNode node, string xpath)
{
foreach (XObject xObject in (IEnumerable)node.XPathEvaluate(xpath))
{
if (xObject is XElement)
yield return ((XElement)xObject).Value;
else if (xObject is XAttribute)
yield return ((XAttribute)xObject).Value;
}
}

XElement and XAttribute are both forms of XObject, so if a generic instance of type XObject will suffice for your needs, change your Cast<XAttribute> to Cast<XObject>.
If that won't work for your specific situation, you make use of OfType<XAttribute> or OfType<XElement> to filter for one or the other, but that would require two passes over the input, one to filter for XElement and a second pass to filter for XAttribute.

Before you make the cast you can check for the type using a code like this:
XElement e = item as XElement;
XAttribute a = item as XAttribute;
if(e != null)
//item is of type XElement
else
//item is of type XAttribute

C# Xml Value always getting null

I have the following Xml in my Resources.xmltest:
<?xml version="1.0" encoding="utf-8" ?>
<Response xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://DFISofft.com/SmartPayments/">
<Result>0</Result>
<Message>Pending</Message>
<PNRef>222131</PNRef>
<ExtData>InvNum=123</ExtData>
</Response>
I've tried several ways to get the values, Result,Message,PNRef,ExtData, out of it and I've had no luck. I always get a null value for the NodePath so it never goes into the loop:
var XmlDoc = new XmlDocument();
XmlDoc.LoadXml(Resources.xmltest);
XmlElement NodePath = (XmlElement) XmlDoc.SelectSingleNode("/Response");
while (NodePath != null)
{
foreach (XmlNode Xml_Node in NodePath)
{
Console.WriteLine(Xml_Node.Name + " " + Xml_Node.InnerText);
}
}
I've tried this:
XmlNode node3 = XmlDoc.SelectSingleNode("PNRef");
Console.WriteLine(node3.Value);
Console.WriteLine(XmlDoc.InnerXml);
var tst = XmlDoc.GetElementsByTagName("PNRef");
Console.WriteLine(tst);
And this:
NodePath = (XmlElement) XmlDoc.SelectSingleNode("/Response");
if (NodePath != null)
{
foreach (XmlNode node in NodePath)
{
Console.WriteLine("NodeName: " + Xml_NodeX.Name);
Console.WriteLine("NodeValue: " + node.InnerText);
}
}
Apparently, I'm not getting the xml read/write. I've done it with DataSets but they do all the work for you.
Can someone point me in the right direction? I've been at this for longer than I should have been already.
Thank you!

Your XML has a XML namespace and you're not paying any attention to it:
<Response xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns="http://DFISofft.com/SmartPayments/">
******************************************
When selecting from this XML, you need to use that XML namespace!
You're not taking into account the XML namespace (xmlns="http://nts-de-osm1-pxc/webservices/") on the document!
Try this:
var XmlDoc = new XmlDocument();
// setup the XML namespace manager
XmlNamespaceManager mgr = new XmlNamespaceManager(XmlDoc.NameTable);
// add the relevant namespaces to the XML namespace manager
mgr.AddNamespace("ns", "http://DFISofft.com/SmartPayments/");
XmlDoc.LoadXml(Resources.xmltest);
// **USE** the XML anemspace in your XPath !!
XmlElement NodePath = (XmlElement) XmlDoc.SelectSingleNode("/ns:Response");
while (NodePath != null)
{
foreach (XmlNode Xml_Node in NodePath)
{
Console.WriteLine(Xml_Node.Name + " " + Xml_Node.InnerText);
}
}

The problem is your XPath query, which doesn't specify a namespace - despite the fact that your document only has a Response element in the "http://DFISofft.com/SmartPayments/" namespace. Ditto the PNRef elements.
Personally I'd use LINQ to XML if I actually wanted to use namespaces if at all possible. For example:
XNamespace ns = "http://DFISofft.com/SmartPayments/";
XDocument doc = XDocument.Load(filename);
foreach (var element in doc.Descendants(ns + "PNRef"))
{
// Use element here
}
As you can see, LINQ to XML makes it really easy to use namespaces - but of course it requires .NET 3.5 or higher. If I had to use .NET 2.0, I'd either use XmlNamespaceManager or iterate manually and check local names instead of using XPath.

That is because the node isn't called response; you need to take the namespace into account:
var XmlDoc = new XmlDocument();
var nsmgr = new XmlNamespaceManager(XmlDoc.NameTable);
nsmgr.AddNamespace("x", "http://DFISofft.com/SmartPayments/");
XmlDoc.LoadXml(yourXml);
XmlElement NodePath = (XmlElement)XmlDoc.SelectSingleNode("/x:Response", nsmgr);

For future reference...
Bubba Soft
This site has a great free tool for building XPath Expressions (XPath Builder).

It's because you are using the overload of SelectSingleNode that assumes an empty namespace. Since you have a default namespace you will need to use the version that takes an XmlNamespaceManager. See this article for more info.
from the docs:
If the XPath expression does not include a prefix, it is assumed that the namespace URI is the empty namespace. If your XML includes a default namespace, you must still add a prefix and namespace URI to the XmlNamespaceManager; otherwise, you will not get a node selected. For more information, see Select Nodes Using XPath Navigation.