Search XDocument using LINQ without knowing the namespace

Question

Is there a way to search an XDocument without knowing the namespace? I have a process that logs all SOAP requests and encrypts the sensitive data. I want to find any elements based on name. Something like, give me all elements where the name is CreditCard. I don't care what the namespace is.

My problem seems to be with LINQ and requiring a xml namespace.

I have other processes that retrieve values from XML, but I know the namespace for these other process.

XDocument xDocument = XDocument.Load(@"C:\temp\Packet.xml");
XNamespace xNamespace = "http://CompanyName.AppName.Service.Contracts";

var elements = xDocument.Root
                        .DescendantsAndSelf()
                        .Elements()
                        .Where(d => d.Name == xNamespace + "CreditCardNumber");

I really want to have the ability to search xml without knowing about namespaces, something like this:

XDocument xDocument = XDocument.Load(@"C:\temp\Packet.xml");
var elements = xDocument.Root
                        .DescendantsAndSelf()
                        .Elements()
                        .Where(d => d.Name == "CreditCardNumber")

This will not work because I don't know the namespace beforehand at compile time.

How can this be done?

<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
<s:Body xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <Request xmlns="http://CompanyName.AppName.Service.ContractA">
        <Person>
            <CreditCardNumber>83838</CreditCardNumber>
            <FirstName>Tom</FirstName>
            <LastName>Jackson</LastName>
        </Person>
        <Person>
            <CreditCardNumber>789875</CreditCardNumber>
            <FirstName>Chris</FirstName>
            <LastName>Smith</LastName>
        </Person>
        ...

<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
<s:Body xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <Request xmlns="http://CompanyName.AppName.Service.ContractsB">
        <Transaction>
            <CreditCardNumber>83838</CreditCardNumber>
            <TransactionID>64588</FirstName>
        </Transaction>      
        ...

Zoroastrian

Answer 1

As Adam precises in the comment, XName are convertible to a string, but that string requires the namespace when there is one. That's why the comparison of .Name to a string fails, or why you can't pass "Person" as a parameter to the XLinq Method to filter on their name.
XName consists of a prefix (the Namespace) and a LocalName. The local name is what you want to query on if you are ignoring namespaces.
Thank you Adam :)

You can't put the Name of the node as a parameter of the .Descendants() method, but you can query that way :

var doc= XElement.Parse(
@"<s:Envelope xmlns:s=""http://schemas.xmlsoap.org/soap/envelope/"">
<s:Body xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"" xmlns:xsd=""http://www.w3.org/2001/XMLSchema"">
  <Request xmlns=""http://CompanyName.AppName.Service.ContractA"">
    <Person>
        <CreditCardNumber>83838</CreditCardNumber>
        <FirstName>Tom</FirstName>
        <LastName>Jackson</LastName>
    </Person>
    <Person>
        <CreditCardNumber>789875</CreditCardNumber>
        <FirstName>Chris</FirstName>
        <LastName>Smith</LastName>
    </Person>
   </Request>
   </s:Body>
</s:Envelope>");

EDIT : bad copy/past from my test :)

var persons = from p in doc.Descendants()
              where p.Name.LocalName == "Person"
              select p;

foreach (var p in persons)
{
    Console.WriteLine(p);
}

That works for me...

Gaona

Might help to put some explanation of why your answer is the way it is: Name is an XName, and XName just happens to be convertible to a string, so the comparison of .Name to a string fails with the question asker's query. XName consists of a prefix and a local name, and the local name is what you want to query on if you are ignoring namespaces. – Cinnabar

that was in the comment that I have put in somerockstar answer. I can add this for clarity, you're right – Halley

Thanks alot for the quick help. Hopefully this will help someone else. – Zoroastrian

Hope so, I got stuck on the same problem the first time using XLinq :) – Halley

@MikeBarlow-BarDev it did ;-) – Marron

Answer 2

You could take the namespace from the root-element:

XDocument xDocument = XDocument.Load(@"C:\temp\Packet.xml");
var ns = xDocument.Root.Name.Namespace;

Now you can get all desired elements easily using the plus-operator:

root.Elements(ns + "CreditCardNumber")

Threeply

This seems like the better answer, as it still lets you use the majority of LINQ operations. – Cheerio

This answer is only acceptable if none of the elements are in a different namespace as the root document. Yes, it's easy to know the namespace if you just ask the root document for it, but its trickier to ask for any elements of a given name, regardless of what namespace the element itself may be in. That's why I consider answer's using XElement.Name.LocalName (usually via linq) are more generalized. – Phlegmatic

This answer is not general enough. – Weiman

Answer 3

I think I found what I was looking for. You can see in the following code I do the evaluation Element.Name.LocalName == "CreditCardNumber". This seemed to work in my tests. I'm not sure if it's a best practice, but I'm going to use it.

XDocument xDocument = XDocument.Load(@"C:\temp\Packet.xml");
var elements = xDocument.Root.DescendantsAndSelf().Elements().Where(d => d.Name.LocalName == "CreditCardNumber");

Now I have elements where I can encrypt the values.

If anyone has a better solution, please provide it. Thanks.

Zoroastrian

That's a perfect solution if you don't know the namespace nor care about it. Thank you! – Mathias

Answer 4

There's a couple answers with extension methods that have been deleted. Not sure why. Here's my version that works for my needs.

public static class XElementExtensions
{
    public static XElement ElementByLocalName(this XElement element, string localName)
    {
        return element.Descendants().FirstOrDefault(e => e.Name.LocalName == localName && !e.IsEmpty);
    }
}

The IsEmpty is to filter out nodes with x:nil="true"

There may be additional subtleties - so use with caution.

Marron

Lovely! Thanks Simon. I would almost say this should be the only correct answer....if you're doing this once then you'll be doing it 100 times and all the other answers are pretty clumsy compared to: el.ElementByLocalName("foo") . – Dalury

Answer 5

If your XML documents always defines the namespace in the same node (Request node in the two examples given), you can determine it by making a query and seeing what namespace the result has:

XDocument xDoc = XDocument.Load("filename.xml");
//Initial query to get namespace:
var reqNodes = from el in xDoc.Root.Descendants()
               where el.Name.LocalName == "Request"
               select el;
foreach(var reqNode in reqNodes)
{
    XNamespace xns = reqNode.Name.Namespace;
    //Queries making use of namespace:
    var person = from el in reqNode.Elements(xns + "Person")
                 select el;
}

Transsonic

Answer 6

I a suffering from a major case of "I know that is the solution, but I am disappointed that that is the solution"... I recently wrote a query like the one below (which I will shortly replace, but it has educational value):

var result = xdoc.Descendants("{urn:schemas-microsoft-com:rowset}data")
.FirstOrDefault()?
.Descendants("{#RowsetSchema}row");

If I remove the namespaces from the XML, I can write the same query like this:

var result = xdoc.Descendants("data")
.FirstOrDefault()?
.Descendants("row");

I plan to write my own extension methods that should allow me to leave the namespaces alone and search for nodes like this:

var result = xdoc.Descendants("rs:data") 
.FirstOrDefault()?
.Descendants("z:row"); 
//'rs:' {refers to urn:schemas-microsoft-com:rowset}
//'z:' {refers to xmlns:z=#RowsetSchema}

My comments just below the code point to how I would like to hide the ugliness of the solution in an Extension Methods library. Again, I'm aware of the solutions posted earlier - but I wish the API itself handled this more fluently. (See what I did there?)

Given

Answer 7

Just use the Descendents method:

XDocument doc = XDocument.Load(filename);
String[] creditCards = (from creditCardNode in doc.Root.Descendents("CreditCardNumber")
                        select creditCardNode.Value).ToArray<string>();

Teresita

that won't work since the descendant parameter asks for an XName, and the XName is prefixed by a namespace here. – Halley