Descendants within descendants in LINQ to XML

Question

I'm struggling to navigate to my 'user' element in my XML; I want a set of users so I can then extract username details. My LINQ query is as follows and always returns 0 for the count (though is not null)

var xApprovers = from d in doc.Root.Descendants("document_version")
                               .Elements("stages")
                               .Elements("stage")
                               .Elements("user")
                               .Elements("approver_list")
                               .Elements("approver")
                               .Elements("user")
                 where d.Element("docVersionID").Value == vId
                 select d;

My XML source is:

<Root>
<document_version>
    <version_number>1</version_number>
    <version_comments></version_comments>
    <creation_date>2011-12-20 09:20:42.877</creation_date>
    <docVersionID>00002_0000000453</docVersionID>
    <pageno>-1</pageno>
    <author>
      <user>
        <userID>00002_0000000001</userID>
        <login>ACRE_ROBOT</login>
        <lastname>ROBOT</lastname>
        <firstname>ACRE</firstname>
        <email>richardtaylor@vcg-kestrel.com</email>
      </user>
    </author>
    <document_approval_cycle_code>0</document_approval_cycle_code>
    <document_approval_cycle_status>Not Started</document_approval_cycle_status>
    <stage_index>1</stage_index>
    <stages>
      <stage>
        <stage_id>00002_0000001017</stage_id>
        <name></name>
        <index>1</index>
        <conditional_approval>1</conditional_approval>
        <upon_rejection_code>0</upon_rejection_code>
        <stage_approval_cycle_code>0</stage_approval_cycle_code>
        <stage_approval_cycle_status>Not Started</stage_approval_cycle_status>
        <stage_approval_code>00001_0000000002</stage_approval_code>
        <stage_approval_status>Pending</stage_approval_status>
        <approver_list>
          <approver>
            <user>
              <userID>00002_0000000011</userID>
              <login>DEVAPP78@APPROVER.COM</login>
              <lastname>App 78</lastname>
              <firstname>Dev</firstname>
              <email>DevApp78@approver.com</email>
            </user>
            <approval_action />
          </approver>
          <approver>
            <user>
              <userID>00002_0000000010</userID>
              <login>DEVAPP77@APPROVER.COM</login>
              <lastname>App 77</lastname>
              <firstname>Dev</firstname>
              <email>DevApp77@approver.com</email>
            </user>
            <approval_action />
          </approver>
        </approver_list>
      </stage>
    </stages>
    <approvals></approvals>
</document_version>
</Root>

What am I doing wrong? Thanks in advance.

So you need all `users` of a `document_version` by `docVersionID` given, right? — abatishchev, Dec 20 '11 at 14:35

Pencho Ilchev · Answer 1 · 2011-12-20T14:34:01.253

2

you have an extra user selection. Try

var xApprovers = from d in doc.Root
                              .Descendants("document_version")
                 where d.Element("docVersionID").Value == vId
                 select d.Elements("stages")
                              .Elements("stage")
                              .Elements("approver_list")
                              .Elements("approver")
                              .Elements("user");

edited Dec 20 '11 at 14:34

answered Dec 20 '11 at 14:13

Pencho Ilchev

3,201
18
21

If I take away the where statement it works, but with it does not... any ideas why? Thanks – Ian Dec 20 '11 at 14:28
Now it's same as my :) But both returns `IEnumerable>`, aren't they? – abatishchev Dec 20 '11 at 14:37

score 2 · Accepted Answer · answered Dec 20 '11 at 17:08

You had two problems, you had an extra .Elements("user") which wasn't necessary

You also were trying to apply the where clause to the wrong element

Here's the corrected LINQ which returns the result in the same IEnumerable<XElement> as your original

  var xGood = from docVersion in doc.Root.Descendants( "document_version" )
              where docVersion.Element("docVersionID").Value == vId
              from d in docVersion.Elements( "stages" )
                                  .Elements( "stage" )
                                  .Elements( "approver_list" )
                                  .Elements( "approver" )
                                  .Elements( "user" )
              select d;

The notable difference between this LINQ and abatishchev's is that this would support multiple document_version nodes in a single xml document

Thank you Merick, that's perfect. – Ian Dec 20 '11 at 17:21 — Ian, Dec 20 '11 at 17:21

abatishchev · Answer 3 · 2011-12-20T14:44:40.743

1

Why don't just this:

from d in doc.Root.Descendants("document_version")
where d.Element("docVersionID").Value == vId
select d.Elements("stages")
        .Elements("stage")
        .Elements("approver_list")
        .Elements("approver")
        .Elements("user");

or

doc.Root
   .Descendants("document_version")
   .SingleOrDefault(d => d.Element("docVersionID").Value == vId).Elements("stages") // sic!
   .Elements("stage")
   .Elements("approver_list")
   .Elements("approver")
   .Elements("user");

Or run XPath:

(IEnumerable)doc.XPathEvaluate(String.Format("Root/document_version/docVersionID[text()='{0}']/../stages/stage/approver_list/approver/user", vId));

edited Dec 20 '11 at 14:44

answered Dec 20 '11 at 14:21

abatishchev

98,240
88
296
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Your linq would be slightly different returning an IEnumerable> rather than an IEnumerable like the original – MerickOWA Dec 20 '11 at 14:29
@Merick: `SingleOrDefault()` should fix that – abatishchev Dec 20 '11 at 14:40
@Merick: btw, OP's query returns `IEnumerable` :) – abatishchev Dec 20 '11 at 14:46
2

SingleOrDefault limits the xml to one document_version which might not be correct – MerickOWA Dec 20 '11 at 17:05
@Merick: I think that's unique ID among the document. OP can proof me wrong. – abatishchev Dec 20 '11 at 17:48

Descendants within descendants in LINQ to XML

3 Answers3