C# Linq XML Query where multiple elements of same name from a parent node based on a child node value

Question

I am a newbie and trying to retrieve all the values of file node based on below xml.

<Changes>
  <Change id="Rest">
    <Name>Restructure</Name>
    <TIDE>
      <Files>
        <File>REGION</File>
      </Files>
    </TIDE>
    <Click>
      <Files>
        <File>DISTRICT</File>
      </Files>
    </Click>
  </Change>
  <Change id="st">
    <Name>New ST</Name>
    <TIDE>
      <Files>
        <File>REGION</File>
      </Files>
    </TIDE>
    <Click>
      <Files>
        <File>DISTRICT</File>
      </Files>
    </Click>
  </Change>
</Changes>

The code I am using is giving me an error "Sequence contains no elements". I have tried to build this code by searching couple of examples on this forum. Can some one help me, much appreciated.

var items = (from i in xmldoc.Root.Elements("Change")
                         where (string)i.Element("Name").Value == listBox1.SelectedValue.ToString()
                         select i).First().Elements("File").ToList();

Yes, the listbox contain values - Restructure and New St and based on the item selected, I need to populate another listbox. — coolcake
– coolcake, Commented Apr 27, 2015 at 4:55

Wug · Accepted Answer · 2015-04-28 23:12:33Z

2

This LINQ query returns Change nodes:

(from i in xmldoc.Root.Elements("Change")
 where (string)i.Element("Name").Value == listBox1.SelectedValue.ToString()
 select i)

... and Change nodes don't have direct child node File. You can use Descendants() instead of Elements() for this case.

var items = (from i in xmldoc.Root.Descendants("Change")
             where i.Element("Name").Value == listBox1.SelectedValue.ToString()
             select i).First().Descendants("File").ToList();

edited Apr 28, 2015 at 23:12

Wug

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answered Apr 27, 2015 at 4:47

har07

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2 Comments

coolcake Over a year ago

Hi har07, thanks for your response, before posting here, i have even tried with descendants and it too didnt work. Here is the code XDocument xmldoc = XDocument.Load("Change_Files_List.xml"); var items = (from i in xmldoc.Root.Descendants("Change") where (string)i.Element("Name").Value == "Restructure"//listBox1.SelectedValue.ToString() select i).First().Elements("File").ToList();

coolcake Over a year ago

var items = (from i in xmldoc.Root.Descendants("Change") where (string)i.Element("Name").Value == "Restructure"//listBox1.SelectedValue.ToString() select i).First().Descendants("File").ToList();

Rodrigo López · Accepted Answer · 2015-04-27 05:04:19Z

1

This error you are getting:

"Sequence contains no elements"

Is beeing throwed by the First() Method call. First() Expects at least one result to be listed, and your filter in Where clause is removing all the results (probably not getting Names correctly from the listbox).

I tested on my machine, replacing the listBox1.SelectedValue.ToString() for "Restructure" and the error doesn't happens anymore.

Even though the exception was not throwed, the result was not as you expected, the items list was empty. To address this other issue you must follow har07 response, and everything will work just fine.

edited Apr 27, 2015 at 5:04

answered Apr 27, 2015 at 4:59

Rodrigo López

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1 Comment

coolcake Over a year ago

Thanks Lopez, I tried both of yours suggestions and still didnt resolve my problem.

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