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LINQ xml finding nodes returns null

I try to parse an xml file with XDocument class, with criteria that if the child node matches a given string, its parent node is selected.
<SalesQuotes xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://api.some.com/version/1">
<Pagination>
<NumberOfItems>2380</NumberOfItems>
<PageSize>200</PageSize>
<PageNumber>1</PageNumber>
<NumberOfPages>12</NumberOfPages>
</Pagination>
<SalesQuote>
<Guid>825634b9-28f5-4aa7-98e7-5e4a4ed6bc6a</Guid>
<LastModifiedOn>2018-01-09T12:23:56.6133445</LastModifiedOn>
<Comments>Please note:
installation is not included in this quote
</Comments>
</SalesQuote>
</SalesQuotes>
I tried using
var contents = File.ReadAllText(path: "test1.xml");
var doc = XDocument.Parse(contents);
var root = doc.Root;
var sq = root.Elements("SalesQuote");//return null
var theQuote = root.Elements("SalesQuote").Where(el => el.Element("Guid").Value == "825634b9-28f5-4aa7-98e7-5e4a4ed6bc6a");//return null
var theAlternativeQuote =
from el in doc.Descendants("SalesQuote").Elements("Guid")
where el.Value == "825634b9-28f5-4aa7-98e7-5e4a4ed6bc6a"
select el;//return null
I can't seem to find what's wrong.
Any help is much appreciated! Thanks.

You ignored the namespace bro.
Do remove the xmlns attribute in your XML or try this:
var contents = File.ReadAllText("XMLFile1.xml");
var doc = XDocument.Parse(contents);
var root = doc.Root;
XNamespace ns = "http://api.some.com/version/1";
var sq = root.Descendants(ns + "SalesQuotes"); //return null
var theQuote = root.Elements(ns + "SalesQuote")
.Where(el => el.Element(ns + "Guid").Value == "825634b9-28f5-4aa7-98e7-5e4a4ed6bc6a"); //return null
var theAlternativeQuote =
from el in doc.Descendants(ns + "SalesQuote").Elements(ns + "Guid")
where el.Value == "825634b9-28f5-4aa7-98e7-5e4a4ed6bc6a"
select el; //return null

If you are not too concerned about keeping your current implementation, you could consider using a Typed DataSet and load your XML into fully typed, structured objects.
Querying those objects with Linq will be more straight forward than what I see in your current implementation.
You might also find this useful:
SO Question: Deserialize XML Document to Objects

yap, you're missing the namespace that you can grab with document.Root.GetDefaultNamespace()
// Load
var document = XDocument.Parse(xml);
var xmlns = document.Root.GetDefaultNamespace();
// Find
var query = from element in document
.Descendants(xmlns + "SalesQuote")
.Elements(xmlns + "Guid")
where element.Value == "825634b9-28f5-4aa7-98e7-5e4a4ed6bc6a"
select element;

How to extract xml child element

I am trying to figure out the code to extract xml child (I think this is worded correctly) elements. I have searched and tried many samples but cannot find how to drill down to pick out the section I want and return the information I need. Maybe I all I need is someone to define the data I am trying to pull so I can read up on the issue, of course any code would be very helpful and I will figure it out from there. Thanks in advanced for any help!
Here is the xml file. I am trying to run an if statement to find the section named <STATISTICTYPE>PVCAP_CharactersSaved</STATISTICTYPE> and return the <JOBNAME>,<TIMEDELTA>,<VALUESUM>.
<?xml version="1.0" encoding="utf-8"?>
<PVCAPTURESTATISTICCONTAINTER xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<PVCAPTUREJOBSTATISTICS>
<PVCAPTURESTATISTICSUMMARY>
<STATISTICTYPE>PVCAP_CharactersSaved</STATISTICTYPE>
<STATISTICNAME>Characters saved</STATISTICNAME>
<JOBID>24</JOBID>
<JOBNAME>HEAT FILES</JOBNAME>
<TIMEDELTA>422</TIMEDELTA>
<VALUESUM>25432</VALUESUM>
</PVCAPTURESTATISTICSUMMARY>
<PVCAPTURESTATISTICSUMMARY>
<STATISTICTYPE>PVCAP_CharactersSaved_NoMM</STATISTICTYPE>
<STATISTICNAME>Characters saved (no match and merge)</STATISTICNAME>
<JOBID>24</JOBID>
<JOBNAME>HEAT FILES</JOBNAME>
<TIMEDELTA>422</TIMEDELTA>
<VALUESUM>25432</VALUESUM>
</PVCAPTURESTATISTICSUMMARY>
</PVCAPTUREJOBSTATISTICS>
<DOCUMENTCOUNT>762</DOCUMENTCOUNT>
<PAGECOUNT>3194</PAGECOUNT>
<IMAGECOUNT>3194</IMAGECOUNT>
<VERSION>2.0</VERSION>
</PVCAPTURESTATISTICCONTAINTER>

You can use LINQ to XML, particularly the XElement class.
var element = XElement.Parse(xmlStr).Element("PVCAPTUREJOBSTATISTICS")
.Elements("PVCAPTURESTATISTICSUMMARY")
.First(c => c.Element("STATISTICTYPE").Value == "PVCAP_CharactersSaved")
var jobName = element.Element("JOBNAME").Value;
var timeDelta = element.Element("TIMEDELTA").Value;
var valueSum = element.Element("VALUESUM").Value;
You'll want to add in some error handling and whatnot here, but this should get you going in the right direction.

You can do something like this:
XElement res = XElement.Parse(xmlResult);
foreach(var elem in res.Element("PVCAPTUREJOBSTATISTICS").Elements("PVCAPTURESTATISTICSUMMARY"))
{
if (elem.Element("STATISTICTYPE").Value.Equals("PVCAP_CharactersSaved", StringComparison.Ordinal))
{
string jobName = elem.Element("JOBNAME").Value;
string timeDelta = elem.Element("TIMEDELTA").Value;
string valueSum = elem.Element("VALUESUM").Value;
}
}

You can use XDocument and LINQ-to-XML to do that quite easily, for example :
string xml = "your xml content here";
XDocument doc = XDocument.Parse(xml);
//or if you have the xml file instead :
//XDocument doc = XDocument.Load("path_to_xml_file.xml");
var result = doc.Descendants("PVCAPTURESTATISTICSUMMARY")
.Where(o => (string) o.Element("STATISTICTYPE") == "PVCAP_CharactersSaved")
.Select(o => new
{
jobname = (string) o.Element("JOBNAME"),
timedelta = (string) o.Element("TIMEDELTA"),
valuesum = (string) o.Element("VALUESUM")
});
foreach (var r in result)
{
Console.WriteLine(r);
}

Parsing specific part of XML file

I have a .gpx XML file with the following sample:
<trk>
<name>Test</name>
<trkseg>
<trkpt lon="-84.89032996818423" lat="32.75810896418989">
<ele>225.0</ele>
<time>2011-04-02T11:57:48.000Z</time>
<extensions>
<gpxtpx:TrackPointExtension>
<gpxtpx:cad>0</gpxtpx:cad>
</gpxtpx:TrackPointExtension>
</extensions>
</trkpt>
</trkseg>
</trk>
I'm using Linq to XML to parse this but I'm having a difficult time parsing the extensions section. Here's the code I'm using:
var gpxDoc = LoadFromStream(document);
var gpx = GetGpxNameSpace();
var gpxtpx = XNamespace.Get("gpxtpx");
var tracks = from track in gpxDoc.Descendants(gpx + "trk")
select new
{
Name = DefaultStringValue(track, gpx, "name"),
Description = DefaultStringValue(track, gpx, "desc"),
Segments = (from trkSegment in track.Descendants(gpx + "trkseg")
select new
{
TrackSegment = trkSegment,
Points = (from trackpoint in trkSegment.Descendants(gpx + "trkpt")
select new
{
Lat = Double(trackpoint.Attribute("lat").Value),
Lng = Double(trackpoint.Attribute("lon").Value),
Ele = DefaultDoubleValue(trackpoint, gpx, "ele"),
Time = DefaultDateTimeValue(trackpoint, gpx, "time"),
Extensions = (
from ext in trackpoint.Descendants(gpx + "extensions").Descendants(gpxtpx + "TrackPointExtension")
select new
{
Cad = DefaultIntValue(ext, gpxtpx, "cad")
}).SingleOrDefault()
})
})
};
Here's the relevant helper code:
private static double? DefaultIntValue(XContainer element, XNamespace ns, string elementName)
{
var xElement = element.Element(ns + elementName);
return xElement != null ? Convert.ToInt32(xElement.Value) : (int?)null;
}
private XNamespace GetGpxNameSpace()
{
var gpx = XNamespace.Get("http://www.topografix.com/GPX/1/1");
return gpx;
}
The actual error I'm getting is
The following error occurred: Object reference not set to an instance of an object.
and it bombs on this code:
Extensions = (from ext in trackpoint.Descendants(gpx + "extensions").Descendants(gpxtpx + "TrackPointExtension")
select new
{
Cad = DefaultIntValue(ext, gpxtpx, "cad")
}).SingleOrDefault();
I just don't know how to fix it.

Since you never declare the namespace (xmlns:gpxtpx="http://www.topografix.com/GPX/1/1") it is never going to match. The xml fragment you provided is not well formed due to the lack of the namespace.
If the fragment posted is snipped from a larger document, consider switching to XML API's rather than string manipulation. If that is the entirety of the XML you receive from an outside system, add it to a root node which you can declare the schema in:
<root xmlns:gpxtpx="http://www.topografix.com/GPX/1/1">
<!-- put your xml fragment here -->
</root>

Noob LINQ - reading, filtering XML with XDocument

I'm just learning XDocument and LINQ queries. Here's some simple XML (which doesn't look formatted exactly right in this forum in my browser, but you get the idea . . .)
<?xml version="1.0" encoding="utf-8"?>
<quiz
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.example.com/name XMLFile2.xsd"
title="MyQuiz1">
<q_a>
<q_a_num>1</q_a_num>
<q_>Here is question 1</q_>
<_a>Here is the answer to 1</_a>
</q_a>
<q_a>
<q_a_num>2</q_a_num>
<q_>Here is question 2</q_>
<_a>Here is the answer to 2</_a>
</q_a>
</quiz>
I can iterate across all elements in my XML file and display their Name, Value, and NodeType in a ListBox like this, no problem:
XDocument doc = XDocument.Load(sPath);
IEnumerable<XElement> elems = doc.Descendants();
IEnumerable<XElement> elem_list = from elem in elems
select elem;
foreach (XElement element in elem_list)
{
String str0 = "Name = " + element.Name.ToString() +
", Value = " + element.Value.ToString() +
", Nodetype = " + element.NodeType.ToString();
System.Windows.Controls.Label strLabel = new System.Windows.Controls.Label();
strLabel.Content = str0;
listBox1.Items.Add(strLabel);
}
...but now I want to add a "where" clause to my query so that I only select elements with a certain name (e.g., "qa") but my element list comes up empty. I tried . . .
IEnumerable<XElement> elem_list = from elem in elems
where elem.Name.ToString() == "qa"
select elem;
Could someone please explain what I'm doing wrong? (and in general are there some good tips for debugging Queries?) Thanks in advance!

The problem is that the Name property is not a string, it's an XName. When you ToString it, you get a lot more than you think.
While it's possible to write the query in the way you're attempting to, also consider these possibilites:
//from nodes immediately below this one
IEnumerable<XElement> elem_list = doc.Elements("qa");
//from nodes of all levels below this node.
IEnumerable<XElement> elem_list = doc.Descendants("qa");

I would perhaps change your query to something that looks more like this
var query = from q_a in document.Descendants("q_a")
select new
{
Number = (int)q_a.Element("q_a_num"),
Question = (string)q_a.Element("q_"),
Answer = (string)q_a.Element("_a")
};
With this, you'll pull from each of your q_a descendants the inner elements into an IEnumerable<[Anonymous Type]>, each object containing the number, question, and answer.
However, if you just want to extract the XElements where the name is q_a, you could do this using a where clause.
IEnumerable<XElement> elem_list = elems.Where(elem => elem.Name.LocalName == "q_a");
Of course, as David B showed, the where clause is not necessary here.
IEnumerable<XElement> elem_list = elems.Elements("q_a");

Using LINQ to XML to Process XML in Multiple Namespaces

I'm trying to parse results from the YouTube API. I'm getting the results correctly as a string, but am unable to parse it correctly.
I followed suggestions on a previous thread, but am not getting any results.
My sample code is:
string response = youtubeService.GetSearchResults(search.Term, "published", 1, 50);
XDocument xDoc = XDocument.Parse(response, LoadOptions.SetLineInfo);
var list = xDoc.Descendants("entry").ToList();
var entries = from entry in xDoc.Descendants("entry")
select new
{
Id = entry.Element("id").Value,
Categories = entry.Elements("category").Select(c => c.Value)
//Published = entry.Element("published").Value,
//Title = entry.Element("title").Value,
//AuthorName = entry.Element("author").Element("name").Value,
//Thumnail = entry.Element("media:group").Elements("media:thumnail").ToList().ElementAt(0)
};
foreach (var entry in entries)
{
// entry.Id and entry.Categories available here
}
The problem is that entries has a count of 0 even though the XDocument clearly has the valid values.
The value of the response variable (Sample XML) can be seen here: http://snipt.org/lWm
(FYI: The youTube schema is listed here: http://code.google.com/apis/youtube/2.0/developers_guide_protocol_understanding_video_feeds.html)
Can anyone tell me what I'm doing wrong here?

All the data is in the "http://www.w3.org/2005/Atom" namespace; you need to use this throughout:
XNamespace ns = XNamespace.Get("http://www.w3.org/2005/Atom");
...
from entry in xDoc.Descendants(ns + "entry")
select new
{
Id = entry.Element(ns + "id").Value,
Categories = entry.Elements(ns + "category").Select(c => c.Value)
...
};
etc (untested)

When you see prefix:name, it means that name is in the namespace whose prefix has been declared as prefix. If you look at the top of the document, you'll see an xmlns:media=something. The something is the namespace used for anything with the prefix media.
This means you need to create an XNamespace for each of the namespaces you need to reference:
XNamespace media = XNamespace.Get("http://search.yahoo.com/mrss/");
and then use media for the names in that namespace:
media + "group"
The namespaces in this document are:
xmlns="http://www.w3.org/2005/Atom"
xmlns:app="http://www.w3.org/2007/app"
xmlns:media="http://search.yahoo.com/mrss/"
xmlns:openSearch="http://a9.com/-/spec/opensearch/1.1/"
xmlns:gd="http://schemas.google.com/g/2005"
xmlns:gml="http://www.opengis.net/gml"
xmlns:yt="http://gdata.youtube.com/schemas/2007"
xmlns:georss="http://www.georss.org/georss"

You need to set the namespace.
Creating an XName in a Namespace
As with XML, an XName can be in a namespace, or it can be in no namespace.
For C#, the recommended approach for creating an XName in a namespace is to declare the XNamespace object, then use the override of the addition operator.
http://msdn.microsoft.com/en-us/library/system.xml.linq.xname.aspx