Develop Reference

XmlNode check if list of chidnodes exists

I am trying to make a function that will take an XmlNode and check if each subsequent child exists and am having issues.
The function should have a signature similar to
private string GetValueForNodeIfExists(XmlNode node, List<string> childNodes){...}
An example illustrating what I would like to accomplish:
I need to know if the child (and possibly a child of a child) of a node exists.
If I have a node which has a child node named "child" and the "child" node has a node named "grandchild" and that grandchild node has a node named "greatGrandchild" then I would like to check if each sequence gives null or not, so checking the following:
node['child'] != null
node['child']['grandchild'] != null
node['child']['grandchild']['greatGrandchild'] != null
the node names I am checking are passed into the function as a List<string> where the index correlates to the depth of the node I am checking. For example, in the above example, the List I would pass in is List<string> checkedasd = new List<String> {"child", "grandchild", "greatGrandchild" };
I am not sure how I can programatically append each ['nodeName'] expression and then execute the expression. If I could figure that out, my strategy would be to throw everything in a try block and if I caught a Null exception then I would know the node doesnt exist.
All help is appreciated

I would use Linq2Xml and XPATH
var childNodes = new List<string>() { "child", "grandchild", "greatGrandchild" };
var xpath = "//" + string.Join("/", childNodes);
var xDoc = XDocument.Load(filename);
var xElem = xDoc.XPathSelectElement(xpath);
if(xElem!=null) //<--- No need for try- catch block
Console.WriteLine(xElem.Value);
PS: I tested the code above code with the following xml
<root>
<child>
<grandchild>
<greatGrandchild>
a
</greatGrandchild>
</grandchild>
</child>
</root>

If you aren't married to XmlDocument and can use Linq2Xml (or want to learn something new) another alternative might be:
DotNetFiddle
using System;
using System.Xml;
using System.Linq;
using System.Xml.Linq;
using System.Collections.Generic;
public class Program
{
public static void Main()
{
//var xDoc = XDocument.Load(filename);
var XDoc = XDocument.Parse(#"<root><a><b><c>value</c></b></a><b><c>no</c></b><a><c>no</c></a></root>");
Console.WriteLine("Params a b c ");
foreach(var nodeValue in XDoc.Root.GetValueForNodeIfExists("a", "b", "c"))
{
Console.WriteLine(nodeValue);
}
Console.WriteLine("List a b c ");
foreach(var nodeValue in XDoc.Root.GetValueForNodeIfExists("a", "b", "c"))
{
Console.WriteLine(nodeValue);
}
}
}
internal static class XElementExtensions
{
public static IEnumerable<string> GetValueForNodeIfExists(this XElement node, params string[] childNodesNames)
{
return GetValueForNodeIfExists(node, childNodesNames.ToList());
}
public static IEnumerable<string> GetValueForNodeIfExists(this XElement node, IEnumerable<string> childNodesNames)
{
IEnumerable<XElement> nodes = new List<XElement> { node };
foreach(var name in childNodesNames)
{
nodes = FilterChildrenByName(nodes, name);
}
var result = nodes.Select(n => n.Value);
return result;
}
private static IEnumerable<XElement> FilterChildrenByName(IEnumerable<XElement> nodes, string filterName)
{
var result = nodes
.SelectMany(n => n.Elements(filterName));
Console.WriteLine("Filtering by {0}, found {1} elements", filterName, result.Count());
return result;
}
}
Results:
Params a b c
Filtering by a, found 2 elements
Filtering by b, found 1 elements
Filtering by c, found 1 elements
value
List a b c
Filtering by a, found 2 elements
Filtering by b, found 1 elements
Filtering by c, found 1 elements
value

All you need to do is use XPath:
private string GetValueForNodeIfExists(XmlNode node, List<string> childNodes)
{
var xpath = string.Join("/", childNodes.ToArray());
var foundNode = node.SelectSingleNode(xpath);
return foundNode != null ? foundNode.InnerText : null;
}
You could also expand on what you already have and just loop through the values until either you get a null value or reach the end:
private string GetValueForNodeIfExists(XmlNode node, List<string> childNodes)
{
foreach (var nodeName in childNodes)
{
if (node != null)
{
node = node[nodeName];
}
}
return node != null ? node.InnerText : null;
}

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();

Unable to remove empty xmlns attribute from XElement using c#

Before posting this question I have tried all other solution on stack, but with no success.
I am unable to remove empty xmlns attribute from XElement using C#, I have tried the following Codes.
XElement.Attributes().Where(a => a.IsNamespaceDeclaration).Remove();
Another one which postted here
foreach (var attr in objXMl.Descendants().Attributes())
{
var elem = attr.Parent;
attr.Remove();
elem.Add(new XAttribute(attr.Name.LocalName, attr.Value));
}

Image This is you xml file
<Root xmlns="http://my.namespace">
<Firstelement xmlns="">
<RestOfTheDocument />
</Firstelement>
</Root>
This is you expect
<Root xmlns="http://my.namespace">
<Firstelement>
<RestOfTheDocument />
</Firstelement>
</Root>
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");
foreach (var node in doc.Root.Descendants())
{
// If we have an empty namespace...
if (node.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(...)
}
}

If you add the namespace of the parent element to the element then the empty namespace tag disappears, as it isn't required because the element is in the same namespace.

here's a simpler way to do this. I believe it happens when you create separate xml segments and then join them to your document.
xDoc.Root.SaveDocument(savePath);
private static void SaveDocument(this XElement doc, string filePath)
{
foreach (var node in doc.Descendants())
{
if (node.Name.NamespaceName == "")
{
node.Name = ns + node.Name.LocalName;
}
}
using (var xw = XmlWriter.Create(filePath, new XmlWriterSettings
{
//OmitXmlDeclaration = true,
//Indent = true,
NamespaceHandling = NamespaceHandling.OmitDuplicates
}))
{
doc.Save(xw);
}
}

Did you try to get Xelement.Attribute by value to see if the element is the "xmlns" before removing.
Xelement.Attribute("xmlns").Value

How do I populate child elements in XML?

I have an xml (Foo.xml)template which is defined as follows:
<Parent:Request xmlns:user="http://xxx.com/">
<Parent:ElemA></Parent:ElemA>
<Parent:ChildNode>
<ElemB></ElemB>
<ElemC></ElemC>
</Parent:ChildNode>
<Parent:ParentName></Parent:ParentName>
</Parent:Request>
In my code, I am able to set the parent elements in the xmltemplate as follows:
public void FooA( MyDomainObject DoM)
{
private readonly XNamespace myNS = "http://ANameSpace.com/";
XElement fooRequestDoc = XElement.Load("Templates/Foo.xml");
XElement ElemA_El = fooRequestDoc.Descendants(myNS + "ElemA").FirstOrDefault();
ElemA_El.SetValue(DoM.ElemA);
}
In this case, if ElemA has a value of "ElementA", then the ElemA_El parameter would be set to this value.
My question is, how do I set a specific Child Note elements such as ElemB or ElemC?
I've tried using "Element" (since I understand it's used to retreive child elements) as follows:
XElement ElemB_El = fooRequestDoc.Element(myNS + "ChildNode");
But it's returning the entire block rather than just ElemB which I seek.

If you know the name of the tag you could do something like this:
XElement ElemB_El = (from node in fooRequestDoc.Descendants() where node.Name == myNS + "ElemB" select node).FirstOrDefault();
If you don't know the name of the tag you can take every Descendants of ChildNode like this:
var nodes = (from node in fooRequestDoc.Descendants(myNS + "ChildNode").Elements() select node).ToList();

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