We Keep Coding

How to read colon in xml file using c# linq

How can I read colon in xml file using c# linq
My code in c#
XDocument xdocc = XDocument.Load(files, LoadOptions.SetLineInfo);
var mml_hi_it = xdocc.Descendants("mml:hi").Where(s => (string)s.Attribute("rend").Value == "it");

The mml literal indicates the namespace used in your xml. You should be able to find the definition in the root node. For example, based on your comment, your root tag looks like following.
<article article-type="research-article" dtd-version="1.1" xml:lang="en" xmlns:mml="w3.org/1998/Math/MathML" xmlns:xlink="w3.org/1999/xlink" xmlns:oasis="niso.org/standards/z39-96/ns/oasis-exchange/table">
In order to access Element with namespace, you need to specify the namespace using XNamespace. For example,
XNamespace mml = "w3.org/1998/Math/MathML";
var mml_hi_it = xdocc.Descendants(mml + "hi").Where(s => (string)s.Attribute("rend").Value == "it");

XDocument get element that defines it's own namespace

As question states. I have a xml document (below) and I need to get X_ScalarWebApi_DeviceInfo that defines namespace urn:schemas-sony-com:av. Unfortunately it results in an error: {System.NullReferenceException: Object reference not set to an instance of an object. I'm mainly interested in ServiceList element, but it doesn't work as well. Platform - Windows 10 mobile.
Any ideas?
<?xml version="1.0"?>
<root xmlns="urn:schemas-upnp-org:device-1-0">
<specVersion>
<major>1</major>
<minor>0</minor>
</specVersion>
<device>
<deviceType>urn:schemas-upnp-org:device:Basic:1</deviceType>
<friendlyName>ILCE-6000</friendlyName>
<manufacturer>Sony Corporation</manufacturer>
<manufacturerURL>http://www.sony.net/</manufacturerURL>
<modelDescription>SonyDigitalMediaServer</modelDescription>
<modelName>SonyImagingDevice</modelName>
<UDN>uuid:000000001000-1010-8000-62F1894EE7BE</UDN>
<serviceList>
<service>
<serviceType>urn:schemas-sony-com:service:ScalarWebAPI:1</serviceType>
<serviceId>urn:schemas-sony-com:serviceId:ScalarWebAPI</serviceId>
<SCPDURL/>
<controlURL/>
<eventSubURL/>
</service>
</serviceList>
<av:X_ScalarWebAPI_DeviceInfo xmlns:av="urn:schemas-sony-com:av">
<av:X_ScalarWebAPI_Version>1.0</av:X_ScalarWebAPI_Version>
<av:X_ScalarWebAPI_ServiceList>
<av:X_ScalarWebAPI_Service>
<av:X_ScalarWebAPI_ServiceType>guide</av:X_ScalarWebAPI_ServiceType>
<av:X_ScalarWebAPI_ActionList_URL>http://192.168.122.1:8080/sony</av:X_ScalarWebAPI_ActionList_URL>
<av:X_ScalarWebAPI_AccessType/>
</av:X_ScalarWebAPI_Service>
<av:X_ScalarWebAPI_Service>
<av:X_ScalarWebAPI_ServiceType>accessControl</av:X_ScalarWebAPI_ServiceType>
<av:X_ScalarWebAPI_ActionList_URL>http://192.168.122.1:8080/sony</av:X_ScalarWebAPI_ActionList_URL>
<av:X_ScalarWebAPI_AccessType/>
</av:X_ScalarWebAPI_Service>
<av:X_ScalarWebAPI_Service>
<av:X_ScalarWebAPI_ServiceType>camera</av:X_ScalarWebAPI_ServiceType>
<av:X_ScalarWebAPI_ActionList_URL>http://192.168.122.1:8080/sony</av:X_ScalarWebAPI_ActionList_URL>
<av:X_ScalarWebAPI_AccessType/>
</av:X_ScalarWebAPI_Service>
</av:X_ScalarWebAPI_ServiceList>
</av:X_ScalarWebAPI_DeviceInfo>
</device>
</root>
Ah, the code:
XDocument xDoc = XDocument.Parse(xml_text);
//var av = xDoc.Root.GetDefaultNamespace();//.Attribute("xmlns");//
XNamespace av = "urn:schemas-sony-com:av";
System.Diagnostics.Debug.WriteLine(av);
<XElement> api_list = (List<XElement>)xDoc.Element(av + "X_ScalarWebAPI_DeviceInfo").Elements();
==EDIT==
Well, both solutions were ok, so I'm upvoting one and marking as answer the other :P
It was mentioned that the solution using only a 'local name' might cause false positive search results, so to be safe I'm using the first one. Thanks for help!

Element only returns elements directly beneath the current node. You need the to specify the entire path (note there are multiple namespaces):
XNamespace ns = "urn:schemas-upnp-org:device-1-0";
XNamespace av = "urn:schemas-sony-com:av";
var api_list = xDoc.Root.Element(ns + "device")
.Element(av + "X_ScalarWebAPI_DeviceInfo").Elements();

Using Xml Linq
XDocument doc = XDocument.Load(FILENAME);
XElement x_ScalarWebAPI_DeviceInfo = doc.Descendants().Where(x => x.Name.LocalName == "X_ScalarWebAPI_DeviceInfo").FirstOrDefault();
XNamespace ns = x_ScalarWebAPI_DeviceInfo.Name.Namespace;

The issue is indeed the Element or Elements methods only search the direct child elements. You can use Decendants() but you will get a collection, so you have to do First(expression) to het a single one.
But in the expression you can use .Name.LocalName to skip the whole namespace thing and look for just the name of the element.
For this question:
XDocument xDoc = XDocument.Parse(xml_text);
XElement x_ScalarWebAPI_DeviceInfo = doc.Descendants().First(x.Name.LocalName == "X_ScalarWebAPI_DeviceInfo");

XML blank attribute creation, issue with ':' character

I am trying to create an xml with the following code.
XmlDocument xmlDocument = new XmlDocument();
XmlProcessingInstruction xPI = xmlDocument.CreateProcessingInstruction("xml", "version='1.0' encoding='UTF-8'");
xmlDocument.AppendChild(xPI);
XmlElement xElmntheader = xmlDocument.CreateElement("soapenv:Header", " ");
xmlDocument.AppendChild(xElmntheader);
MemoryStream ms = new MemoryStream();
xmlDocument.Save(ms);
string text = System.Text.Encoding.GetEncoding("UTF-8").GetString(ms.GetBuffer(), 0, (int)ms.Length);
Output is
<xml version='1.0' encoding='UTF-8'?>
<soapenv:Header xmlns:soapenv=" " />
I was trying to create like this
<xml version='1.0' encoding='UTF-8'?>
<soapenv:Header/>
How do I eliminate xmlns:soapenv=" " from soapenv:Header?
Any help would be greatly appreciated.

What you're asking how to do is create ill-formed (syntactically incorrect) XML. The XmlDocument API is not designed to do that.
If you use the element name
soapenv:Header
that means soapenv is a namespace prefix, which has been declared on this element (or an ancestor) using the xmlns:soapenv pseudoattribute. If it has not been declared, your XML output will not be accepted by any self-respecting XML parser.
The method signature you called,
xmlDocument.CreateElement(string1, string2);
takes two arguments: the qualified name of the element (which may include a prefix, as it does in your case); and a namespace URI. The documentation shows what the expected output is:
The following C# code
XmlElement elem;
elem = doc.CreateElement("xy:item", "urn:abc");
results in an element that is equivalent to the following XML text.
<xy:item xmlns:item="urn:abc"/>
The expected namespace URI for this element is "http://schemas.xmlsoap.org/soap/envelope/". So you will want to declare the soapenv prefix with that namespace URI:
string soapNSURI = "http://schemas.xmlsoap.org/soap/envelope/";
and use it thus:
XmlElement xElmntheader = xmlDocument.CreateElement("soapenv:Header", soapNSURI);

Create without the namespace (e.g. use default namespace) and then that part won't be necessary:
xmlDocument.CreateElement("Header");

Change the default XML xmlns namespace value in .NET

I need to get a list of files from a VS project file. csproj file is XML file, so I use linq to xml to parse it. The problem is in default namespace of csproj file, it is declared like:
xmlns="http://schemas.microsoft.com/developer/msbuild/2003"
Here is the code I use to find "Compile" elements in a csproj file:
XmlReader reader = XmlReader.Create(projectFilePath);
XDocument doc = XDocument.Load(reader);
XmlNameTable nameTable = reader.NameTable;
XmlNamespaceManager nsManager = new XmlNamespaceManager(nameTable);
XNamespace nms = doc.Root.GetDefaultNamespace();
nsManager.AddNamespace("", nms.NamespaceName);
List<XElement> csFiles = new List<XElement>(doc.Root.XPathSelectElements("//Compile", nsManager));
doc.Root.XPathSelectElements returns an empty list.
nsManager.DefaultNamespace has value "http://schemas.microsoft.com/developer/msbuild/2003".
But nsManager.LookupNamespace("xmlns") returns default XML namespace: "http://www.w3.org/2000/xmlns/".
How to change the xmlns namespace value?

Your problem is that you need to be explicit about the namespace with the XPath. It won't just use the default one for the document, you have to name it.
If you change the last two lines to something like this, it will work (I chose the xmlns prefix "default"):
nsManager.AddNamespace("default", nms.NamespaceName);
List<XElement> csFiles = new List<XElement>(doc.Root.XPathSelectElements("//default:Compile", nsManager));
Another option is to use the XContainer methods instead. This way you don't need to worry about using a namespace manager:
XNamespace nms = doc.Root.GetDefaultNamespace();
List<XElement> csFiles = new List<XElement>(doc.Root.Descendants(nms + "Compile"));

Parsing complex XML with C#

I am trying to parse a complex XML with C#, I am using Linq to do it. Basically, I am doing a request to a server and I get XML, this is the code:
XElement xdoc = XElement.Parse(e.Result);
this.newsList.ItemsSource =
from item in xdoc.Descendants("item")
select new ArticlesItem
{
//Image = item.Element("image").Element("url").Value,
Title = item.Element("title").Value,
Description = this.Strip(item.Element("description").Value).Substring(0, 200).ToString()
}
And this is the XML structure:
<item>
<test:link_id>1282570</test:link_id>
<test:user>SLAYERTANIC</test:user>
<title>aaa</title>
<description>aaa</description>
</item>
How I can access to the property test:link_id for example?
Thanks!

Currently your XML is invalid since the test namespace is not declared, you can declare it like this:
<item xmlns:test="http://foo.bar">
<test:link_id>1282570</test:link_id>
<test:user>SLAYERTANIC</test:user>
<title>aaa</title>
<description>aaa</description>
</item>
Having this you can use XNamespace to qualify the XML element you want with the correct namespace:
XElement xdoc = XElement.Parse(e.Result);
XNamespace test = "http://foo.bar";
this.newsList.ItemsSource = from item in xdoc.Descendants("item")
select new ArticlesItem
{
LinkID = item.Element(test + "link_id").Value,
Title = item.Element("title").Value,
Description = this.Strip(item.Element("description").Value).Substring(0, 200).ToString()
}

To write a query on XML that is in a
namespace, you must use XName objects
that have the correct namespace. For
C#, the most common approach is to
initialize an XNamespace using a
string that contains the URI, then use
the addition operator overload to
combine the namespace with the local
name.
To retrieve the value of the link_id element you will need to declare and use an XML namespace for the test:link element.
Since you did not show the namespace declaration in your example XML, I am going to assume it is declared somewhere elese in the XML document. You need to locate the namespace declaration in the XML ( something like xmlns:test="http://schema.example.org" ) which is often declared in the root of the XML document.
After you know this, you can do the following to retrieve the value of the link_id element:
XElement xdoc = XElement.Parse(e.Result);
XNamespace testNamespace = "http://schema.example.org";
this.newsList.ItemsSource = from item in xdoc.Descendants("item")
select new ArticlesItem
{
Title = item.Element("title").Value,
Link = item.Element(testNamespace + "link_id").Value,
Description = this.Strip(item.Element("description").Value).Substring(0, 200).ToString()
}
See the XNamespace and Namespaces in C#, and How to: Write Queries on XML in Namespaces for further information.