how i can list out all the namespace in XML?

Question

My basic requirement is to get element value from the XML file, i have used XMLDoxument.SelectSingleNode. My XML file contains some Namespace in header, so i have used NameSpaceManager to add namespace-prefix and i have used prefix to get that particular element. Now in my XML files that namespaces are getting vary, i don’t want to do any hard coding, is there any way that i can find out all the namespaces and i can add it to NameSpaceManager.

Thanks.

Solution 1

Namespaces can be found anywhere inside xml document. So to extract all namespaces and declare them into a XmlNamespaceManager I did the following:

public static XmlNamespaceManager getAllNamespaces(XmlDocument xDoc)
{
    XmlNamespaceManager result = new XmlNamespaceManager(xDoc.NameTable);

    IDictionary<string, string> localNamespaces = null;
    XPathNavigator xNav = xDoc.CreateNavigator();
    while (xNav.MoveToFollowing(XPathNodeType.Element))
    {
        localNamespaces = xNav.GetNamespacesInScope(XmlNamespaceScope.Local);
        foreach (var localNamespace in localNamespaces)
        {
            string prefix = localNamespace.Key;
            if (string.IsNullOrEmpty(prefix))
                    prefix = "DEFAULT";

            result.AddNamespace(prefix, localNamespace.Value);
        }
    }

    return result;
}

Just pay attention to the default namespace case. I redefined default namespace as "DEFAULT" prefix because I had problems when making SelectSingleNode using the above returned namespace manager when querying the default namespace. I was my workaround. Hope this helps

Solution 2

Your basic problem of retrieving namespaces from an XmlDocument can be solved by simply retrieving the NameTable of the XmlDocument and creating an XmlNameSpaceManager from it.

However, if you want to list the namespaces for some other purpose, you should check out the GetNamespacesInScope method exposed by the XmlNamespaceManager class as well as the XPathNavigator class.

When using an XmlDocument, you can get an XmlNamespaceManager from it via the following code:

//Instantiate an XmlDocument object.
XmlDocument xmldoc = new XmlDocument();

//Load XML file into the XmlDocument object. 
xmldoc.Load("C:\\myFile.xml");

//Instantiate an XmlNamespaceManager object. 
XmlNamespaceManager nsMgr = new XmlNamespaceManager(xmldoc.NameTable);

// Retrieve the namespaces into a Generic dictionary with string keys.
IDictionary<string, string> dic = nsMgr.GetNamespacesInScope(XmlNamespaceScope.All);

// Iterate through the dictionary.

...

In this article, Scott Hanselman presents a way to use this method to list all namespaces in a document using an XPathNavigator and using a LINQ bridge.

Solution 3

Ruchita posted the working solution for XmlDocument. But I wanted to do the same with XDocument. Here is the very same with XDocument:

var xml = XDocument.Load(filename);
var xmlNameSpaceList = ((IEnumerable)xml.XPathEvaluate(@"//namespace::*[not(. = ../../namespace::*)]")).Cast<XAttribute>();
var xmlNSmgr = new XmlNamespaceManager(new NameTable());
foreach (var nsNode in xmlNameSpaceList)
{
    xmlNSmgr.AddNamespace(nsNode.Name.LocalName, nsNode.Value);
}

Now you can use XPath with namespaces, e.g. xml.XPathEvaluate("//test:p", xmlNSmgr).