XML Parsing - Linq

Question

Hi,

I am stuck up in parsing an XML using Linq,

My XMl file is as below... I want to get all the '<File>' node values which matches a specifi <File> node in the <Files> node

For eg: I want to get "fusionserver.log, fmvifmonitor.log, event.log" as a result, when the user passes 'messages' as the input

<?xml version="1.0" encoding="utf-8" ?>
<LogFiles>
  <Files>
    <File>messages</File>
    <File>fusionserver.log</File>
    <File>fmvifmonitor.log</File>
    <File>event.log</File>
    <File>ajscanner.log</File>
  </Files>
  <Files>
    <File>cifsservicemonitor.log</File>
    <File>quotamonitor.err</File>
    <File>Iad.log</File>
    <File>ibrcfrworkerd.log</File>
  </Files>
</LogFiles>

I tried with the below code, it throws exception 'Expression can not contain lambda expressions'

f.Root.Descendants("Files").Where(x => x.Element("File").Value = "messages").Select(x => x.Element("File").Value);

Please help me on this!

Answer 1

Try this code

XElement root = XElement.Parse(xml);
var query = from n in root.Descendants("Files")
                        where n.Descendants("File").Any(f => f.Value == "messages")
                        from f in n.Descendants("File")
                        select f.Value;
string result = string.Join(", ", query);
Console.WriteLine(result);
Console.ReadLine();

---

Miha Markic [MVP C#] http://blog.rthand.com

Answer 2

Thanks you!

I can not hardcode 'messages' in the LinQ query. So I had to rewrite the code as below...

var ff = XDocument.Load("LogsRelationship.xml");

        Expression<Func<XElement, bool>> whereClause = a => a.Element("File").Value == strFileName;

        var query = ff.Descendants("Files").Where(whereClause).Select(x => x.Parent);
        foreach (XElement item in query.Descendants("Files"))
        {
          foreach (XElement it in item.Elements("File"))
          {
           Console.Write(it.Value);
          }
        }

But this gives error "cannot convert from 'System.Collections.Generic.IEnumerable<System.Xml.Linq.XElement>' to 'System.Linq.IQueryable<System.Xml.Linq.XElement>' " in the below line

 var query = ff.Descendants("Files").Where(whereClause).Select(x => x.Parent);

Please help me!

Answer 3

string criteria = "messages";
...
where n.Descendants("File").Any(f => f.Value == criteria)
...

This would work as well.

---

Miha Markic [MVP C#] http://blog.rthand.com