Problem When consuming WCF Rest service

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In My application I Have WCF Rest serivce and i am making call from my silverlight client.

 private void btnGetEmployees_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                WebClient wClient = new WebClient();
                wClient.DownloadStringCompleted += new DownloadStringCompletedEventHandler(wClient_OpenReadCompleted);
                wClient.DownloadStringAsync(new Uri("http://localhost/DummyService/Service.svc/EmpRest", UriKind.Absolute));
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

void wClient_OpenReadCompleted(object sender, DownloadStringCompletedEventArgs e)
        { 
XDocument xdStudent = XDocument.Parse(e.Result);
   var Result = (from emp in xdStudent.Descendants("Employee")
                              select new Employee
                              {
                                 EmpNo = emp.Element("EmpNo").Value,
                                 EmpName = emp.Element("EmpName").Value
                              }
                              ).ToList();

                dgData.ItemsSource = Result;
}

I am able to get the POX result from e.Result . Below is sample results

XML

<ArrayOfEmployee xmlns="http://schemas.datacontract.org/2004/07/WCF_REST_Service" xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
  <Employee>
    <EmpName>Emp_1</EmpName>
    <EmpNo>101</EmpNo>
  </Employee>
  <Employee>
    <EmpName>Emp_2</EmpName>
    <EmpNo>102</EmpNo>
  </Employee>
  <Employee>
    <EmpName>Emp_3</EmpName>
    <EmpNo>103</EmpNo>
  </Employee>
  <Employee>
    <EmpName>Emp_4</EmpName>
    <EmpNo>104</EmpNo>
  </Employee>
  <Employee>
    <EmpName>Emp_5</EmpName>
    <EmpNo>105</EmpNo>
  </Employee>
</ArrayOfEmployee>

But When I am Querying the XDocument Using LINQ I am Not receiving the result. I for testing purpose i have loaded the XDocument manually (Not from the service) as below and able to get values.

C#

string xml = @"
               <ArrayOfEmployee >
                 <Employee>
                   <EmpName>Emp_1</EmpName>
                   <EmpNo>101</EmpNo>
                 </Employee>
                 <Employee>
                   <EmpName>Emp_2</EmpName>
                   <EmpNo>102</EmpNo>
                 </Employee>
                 <Employee>
                   <EmpName>Emp_3</EmpName>
                   <EmpNo>103</EmpNo>
                 </Employee>
                 <Employee>
                   <EmpName>Emp_4</EmpName>
                   <EmpNo>104</EmpNo>
                 </Employee>
                 <Employee>
                   <EmpName>Emp_5</EmpName>
                   <EmpNo>105</EmpNo>
                 </Employee>
               </ArrayOfEmployee>";
               XDocument xdStudent = XDocument.Parse(xml);

The only change i made is .I have removed the attributes from the root tag

XML

xmlns="http://schemas.datacontract.org/2004/07/WCF_REST_Service" xmlns:i="http://www.w3.org/2001/XMLSchema-instance"

I think thiese attributes are causing the parsing issue when i am querying the XDoument Using Linq.

Please help me out. Thanks in Advance

Warm regards,
Hari.

Posted 27-Dec-12 21:20pm

HariPrasad katakam

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Comments

Oleksandr Kulchytskyi 28-Dec-12 3:32am

Yep of course , they cause the parsing issue , because of you forget to add xml namespaces to your xdoc

1 solution

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Oleksandr Kulchytskyi · Answer 1 · 2012-12-27T21:38:00

Solution 1

C#

void wClient_OpenReadCompleted(object sender, DownloadStringCompletedEventArgs e)
{
   XNamespace ns = "http://schemas.datacontract.org/2004/07/WCF_REST_Service";
   XDocument xdStudent = XDocument.Parse(e.Result);
   var Result = (from emp in xdStudent.Descendants(ns +"Employee")
                              select new Employee
                              {
                                 EmpNo = emp.Element("EmpNo").Value,
                                 EmpName = emp.Element("EmpName").Value
                              }
                              ).ToList();

                dgData.ItemsSource = Result;
}

Posted 27-Dec-12 21:38pm

Oleksandr Kulchytskyi

Comments

HariPrasad katakam 28-Dec-12 5:09am

Thanks Oleksandr Kulchytskyi,

I have given the XNamespace.now i am receiving "Object reference not set to an instance of object" error. :( As per my knowledge when consuming rest service need not to add proxy class, please let me know i would wrong.

Oleksandr Kulchytskyi 28-Dec-12 5:14am

Yep, of course you can get rid of creating proxy class...
One of the possible reasons why you cannot receive data it to need specify some additional argument in header request via web client.

Also i would reccomend to add aditional check point:
void wClient_OpenReadCompleted(object sender, DownloadStringCompletedEventArgs e)
{
if(e.Error!=null)
{
// log error state ....
return;
}
XNamespace ns = "http://schemas.datacontract.org/2004/07/WCF_REST_Service";
XDocument xdStudent = XDocument.Parse(e.Result);
var Result = (from emp in xdStudent.Descendants(ns +"Employee")
select new Employee
{
EmpNo = emp.Element("EmpNo").Value,
EmpName = emp.Element("EmpName").Value
}
).ToList();

dgData.ItemsSource = Result;