XDocument and Linq returns null if the element has xmlns attribute

Question

Newbie with XDocuments and Linq, please suggest a solution to retrieve the data from a particular tag in the xml string:

If I have a XML string from webservice response (I formatted xml for ease):

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <soap:Body>
    <GetCashFlowReportResponse xmlns="http://tempuri.org/">
      <GetCashFlowReportPdf>Hello!</GetCashFlowReportPdf>
    </GetCashFlowReportResponse>
  </soap:Body>
</soap:Envelope>

Using the following code, I can get the value only if GetCashFlowReportResponse tag doesn't have "xmlns" attribute. Not sure why? Otherwise, it always return null.

string inputString = "<?xml version=\"1.0\" encoding=\"utf-8\"?><soap:Envelope xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\"><soap:Body><GetCashFlowReportResponse xmlns=\"http://tempuri.org/\"><GetCashFlowReportPdf>Hello!</GetCashFlowReportPdf></GetCashFlowReportResponse></soap:Body></soap:Envelope>"    
XDocument xDoc = XDocument.Parse(inputString);
//XNamespace ns = "http://tempuri.org/";
XNamespace ns = XNamespace.Get("http://tempuri.org/");

var data = from c in xDoc.Descendants(ns + "GetCashFlowReportResponse")
           select (string)c.Element("GetCashFlowReportPdf");

foreach (string val in data)
{
    Console.WriteLine(val);
}

I can't change the web service to remove that attribute. IS there a better way to read the response and get the actual data back to the user (in more readable form)?

Edited: SOLUTION:

XDocument xDoc = XDocument.Parse(inputString);
XNamespace ns = "http://tempuri.org/";

var data = from c in xDoc.Descendants(ns + "GetCashFlowReportResponse")
           select (string)c.Element(ns + "GetCashFlowReportPdf");
foreach (string val in data)
{
   Console.WriteLine(val);
}

Note: Even if all the child elements doesn't have the namespace attribute, the code will work if you add the "ns" to the element as I guess childs inherit the namespace from parent (see response from SLaks).

Thanks for all the responses but not sure why didn't any return any result. I tried all the three solutions and the result was still the same "null". Not sure if I am missing something. Updated code is in my original post. I also tried "spender's" solution but that too returned null. Any idea? — Sri Reddy, May 09 '11 at 17:07

score 16 · Accepted Answer · edited May 09 '11 at 16:17

16

You need to include the namespace:

XNamespace ns = "http://tempuri.org/";

xDoc.Descendants(ns + "GetCashFlowReportResponse")

edited May 09 '11 at 16:17

R. Martinho Fernandes

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answered May 09 '11 at 16:11

SLaks

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1

@user: `GetCashFlowReportPdf` inherits the namespace. You need to add `ns` there too. – SLaks May 09 '11 at 17:35
no, only `GetCashFlowReportResponse` has the namespace.. other elements doesn't have it. – Sri Reddy May 09 '11 at 17:49
2

@user: Wrong. The default namespaces (`xmlns="..."`) is inherited by child elements. – SLaks May 09 '11 at 17:52
If I add the namespace to `GetCashFlowReportPdf` then it works but I don't have access to webservice code to change anything. I am just calling the service dynamically and read the HttpWebResponse. What are my other options? – Sri Reddy May 09 '11 at 18:01
@user: Write `c.Element(ns + "GetCashFlowReportPdf")` – SLaks May 09 '11 at 18:01
@SLaks, I add xmlns attribute to `GetCashFlowReportPdf` element and followed it with the code 'c.Element(ns + "GetCashFlowReportPdf")' which made the code work. This is good for testing. In production, I don't have access to change the webservice. I can't make the response has the namespace for each child element. Not sure how the services are built and why child elements doesn't have a namespace attribute. In that case, is there any option or workaround? – Sri Reddy May 09 '11 at 18:25
ok, I got what you mean by ` The default namespaces (xmlns="...") is inherited by child elements.`. Even if xmlns is not explicitly defined in the xml, the namespace is inherited and I can get the value by adding `ns + "GetCashFlowReportPDF"`. Thanks. I will post the updated code above. – Sri Reddy May 09 '11 at 18:40

score 2 · Answer 2 · answered May 09 '11 at 16:12

2

XName qualifiedName = XName.Get("GetCashFlowReportResponse", 
    "http://tempuri.org/");

var data = from d in xDoc.Descendants(qualifiedName)

answered May 09 '11 at 16:12

spender

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score 2 · Answer 3 · answered May 09 '11 at 16:14

2

Just ask for the elements using the qualified names:

// create a XML namespace object
XNamespace ns = XNamespace.Get("http://tempuri.org/");

var data = from c in xDoc.Descendants(ns + "GetCashFlowReportResponse")
           select (string)c.Element(ns + "GetCashFlowReportPdf");

Note the use of the overloaded + operator that creates a QName with a XML namespace and a local name string.

answered May 09 '11 at 16:14

R. Martinho Fernandes

228,013
71
433
510

What difference it makes to have code like XNamespace ns = "http://tempuri.org/"; and adding XNamespace.Get()? – Sri Reddy May 09 '11 at 17:34
My answer uses an implicit cast; they're equivalent. – SLaks May 09 '11 at 17:52

XDocument and Linq returns null if the element has xmlns attribute

3 Answers3

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