Question

I have a XML Like this:

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope"
               xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
               xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <soap:Body>
        <SampleResponse xmlns="http://tempuri.org/">
            <SampleResult>
                <diffgr:diffgram xmlns:msdata="urn:schemas-microsoft-com:xml-msdata"
                                 xmlns:diffgr="urn:schemas-microsoft-com:xml-diffgram-v1">
                    <NewDataSet xmlns="">
                        <Table diffgr:id="Table1" msdata:rowOrder="0">
                            <tag1>tag1 text</tag1>
                            <tag2>tag2 text</tag2>
                        </Table>
                        <Table diffgr:id="Table2" msdata:rowOrder="1">
                            <tag1>tag1 text</tag1>
                            <tag2>tag2 text</tag2>
                        </Table>
                    </NewDataSet>
                </diffgr:diffgram>
            </SampleResult>
        </SampleResponse>
    </soap:Body>
</soap:Envelope>

here i am parsing above XML Like Below:

   // My parser Class
    class ParseClass 
    { 
        public string tag1 { get; set; }
        public string tag2 { get; set; }
    }

My parsing Code is:

 string XMLresponse = e.response;
    var XResult = XElement.Parse(XMLresponse);
    var result = XResult.Descendants("Table").Select(t => new ParseClass
                 {
                     tag1 = t.Descendants("tag1").First().Value,
                     tag2 = t.Descendants("tag2").First().Value,
                 });
foreach (var res in result1)
                    {
string str=res.tag1;
str=res.tag2;
                    }

I am able parse above XML successfully if all the tags are coming. But some times my response XML is missing tag called tag2, at that time i am not able to parse the XML and giving exception like “sequence contains no elements”.

Here my requirement is:
I have tried FirstOrDefault method in place of First method but no use.
if any tag is missing in XML then that variable should be Null for that Object(i.e: if tag2 is missing then res.tag2 should be null). How can i achieve this?

Answer 1

Instead of using

tag1 = t.Descendants("tag1").First().Value

use

tag1 = (string) t.Descendants("tag1").FirstOrDefault()

(And likewise for tag2.)

FirstOrDefault() will return null if the value isn’t present, and the XElement to string conversion will return null when asked to convert a null reference, or the text content otherwise.