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How to Parse Nested XML Nodes in C#

I am very new to C#, but it seems as though this should be pretty straight forward. I am trying to parse an XML string returned from a web feed that looks like this:
<autnresponse xmlns:autn="http://schemas.autonomy.com/aci/">
<action>QUERY</action>
<response>SUCCESS</response>
<responsedata>
<autn:numhits>6</autn:numhits>
<autn:hit>
<autn:reference>http://something.what.com/index.php?title=DPM</autn:reference>
<autn:id>548166</autn:id>
<autn:section>0</autn:section>
<autn:weight>87.44</autn:weight>
<autn:links>Castlmania,POUCH</autn:links>
<autn:database>Postgres</autn:database>
<autn:title>A Pouch and Mail - Castlmania</autn:title>
<autn:content>
<DOCUMENT>
<DRETITLE>Castlmania Pouch and Mail - Castlmania</DRETITLE>
<DRECONTENT>A paragraph of sorts that would contain content</DRECONTENT>
</DOCUMENT>
</autn:content>
</autn:hit>
<autn:hit>...</autn:hit>
<autn:hit>...</autn:hit>
<autn:hit>...</autn:hit>
<autn:hit>...</autn:hit>
</autnresponse>
with no luck.
I am using this code to start:
XmlDocument xmlString = new XmlDocument();
xmlString.LoadXml(xmlUrl);
XmlElement root = xmlString.DocumentElement;
XmlNode GeneralInformationNode =
root.SelectSingleNode("//autnresponse/responsedata/autn:hit");
foreach (XmlNode node in GeneralInformationNode)
{
Console.Write("reference: "+node["autn:reference"]+" Title:"+node["DRETITLE"]+"<br />);
}
And I would like to print the DRETITLE and autn:reference element of within each of the autn:hit elements. Is that even doable with my approach?
I have tried looking and several example on the good old web like this to no avail.
The error that comes back is:
System.Xml.XPath.XpathEception {NameSpace Manager or XsltContext
needed. ...}
Thanks in advance.
UPDATE:
In trying to use XmlNamespaceManager, one has to give it a url to the schema definition like so:
XmlNamespaceManager namespmng = new XmlNamespaceManager (xmlString.NameTable);
namespmng.AddNamespace("autn","http://someURL.com/XMLschema");
The problem seems to be that now the error is gone, but the data is not displaying. I should mention that I am working off of a machine that does not have internet connectivity. The other thing is the schema seems to be unavailable. I am guessing that XmlNamespaceManager would work once able to connect to the internet right?

Using System.Xml.Linq it could be something like this:
var doc = XElement.Load(xmlUrl);
var ns = doc.GetNamespaceOfPrefix("autn");
foreach (var hit in doc.Descendants(ns + "hit"))
{
var reference = hit.Element(ns + "reference").Value;
var dretitle = hit.Descendants("DRETITLE").Single().Value;
WriteLine($"ref: {reference} title: {dretitle}");
}

Firstly, the exception you're getting is because you haven't loaded the namespace using the XmlNamespaceManager for the xml you're parsing. Something like this:
XmlNamespaceManager namespaceManager = new XmlNamespaceManager(xmlString.NameTable);
if (root.Attributes["xmlns:autn"] != null)
{
uri = root.Attributes["xmlns:autn"].Value;
namespaceManager.AddNamespace("autn", uri);
}
Secondly, what you're trying to do is possible. I'd suggest using root.SelectNodes(<your xpath here>) which will return a collection of autn:hit nodes that you can loop through instead of SelectSingleNode which will return one node. Within that you can drill down to the content/DOCUMENT/DRETITLE and pull the text for the DRETITLE node using either XmlNode.Value if you select the text specifically or XmlNode.InnerText on the DRETITLE node.

XDocument get element that defines it's own namespace

As question states. I have a xml document (below) and I need to get X_ScalarWebApi_DeviceInfo that defines namespace urn:schemas-sony-com:av. Unfortunately it results in an error: {System.NullReferenceException: Object reference not set to an instance of an object. I'm mainly interested in ServiceList element, but it doesn't work as well. Platform - Windows 10 mobile.
Any ideas?
<?xml version="1.0"?>
<root xmlns="urn:schemas-upnp-org:device-1-0">
<specVersion>
<major>1</major>
<minor>0</minor>
</specVersion>
<device>
<deviceType>urn:schemas-upnp-org:device:Basic:1</deviceType>
<friendlyName>ILCE-6000</friendlyName>
<manufacturer>Sony Corporation</manufacturer>
<manufacturerURL>http://www.sony.net/</manufacturerURL>
<modelDescription>SonyDigitalMediaServer</modelDescription>
<modelName>SonyImagingDevice</modelName>
<UDN>uuid:000000001000-1010-8000-62F1894EE7BE</UDN>
<serviceList>
<service>
<serviceType>urn:schemas-sony-com:service:ScalarWebAPI:1</serviceType>
<serviceId>urn:schemas-sony-com:serviceId:ScalarWebAPI</serviceId>
<SCPDURL/>
<controlURL/>
<eventSubURL/>
</service>
</serviceList>
<av:X_ScalarWebAPI_DeviceInfo xmlns:av="urn:schemas-sony-com:av">
<av:X_ScalarWebAPI_Version>1.0</av:X_ScalarWebAPI_Version>
<av:X_ScalarWebAPI_ServiceList>
<av:X_ScalarWebAPI_Service>
<av:X_ScalarWebAPI_ServiceType>guide</av:X_ScalarWebAPI_ServiceType>
<av:X_ScalarWebAPI_ActionList_URL>http://192.168.122.1:8080/sony</av:X_ScalarWebAPI_ActionList_URL>
<av:X_ScalarWebAPI_AccessType/>
</av:X_ScalarWebAPI_Service>
<av:X_ScalarWebAPI_Service>
<av:X_ScalarWebAPI_ServiceType>accessControl</av:X_ScalarWebAPI_ServiceType>
<av:X_ScalarWebAPI_ActionList_URL>http://192.168.122.1:8080/sony</av:X_ScalarWebAPI_ActionList_URL>
<av:X_ScalarWebAPI_AccessType/>
</av:X_ScalarWebAPI_Service>
<av:X_ScalarWebAPI_Service>
<av:X_ScalarWebAPI_ServiceType>camera</av:X_ScalarWebAPI_ServiceType>
<av:X_ScalarWebAPI_ActionList_URL>http://192.168.122.1:8080/sony</av:X_ScalarWebAPI_ActionList_URL>
<av:X_ScalarWebAPI_AccessType/>
</av:X_ScalarWebAPI_Service>
</av:X_ScalarWebAPI_ServiceList>
</av:X_ScalarWebAPI_DeviceInfo>
</device>
</root>
Ah, the code:
XDocument xDoc = XDocument.Parse(xml_text);
//var av = xDoc.Root.GetDefaultNamespace();//.Attribute("xmlns");//
XNamespace av = "urn:schemas-sony-com:av";
System.Diagnostics.Debug.WriteLine(av);
<XElement> api_list = (List<XElement>)xDoc.Element(av + "X_ScalarWebAPI_DeviceInfo").Elements();
==EDIT==
Well, both solutions were ok, so I'm upvoting one and marking as answer the other :P
It was mentioned that the solution using only a 'local name' might cause false positive search results, so to be safe I'm using the first one. Thanks for help!

Element only returns elements directly beneath the current node. You need the to specify the entire path (note there are multiple namespaces):
XNamespace ns = "urn:schemas-upnp-org:device-1-0";
XNamespace av = "urn:schemas-sony-com:av";
var api_list = xDoc.Root.Element(ns + "device")
.Element(av + "X_ScalarWebAPI_DeviceInfo").Elements();

Using Xml Linq
XDocument doc = XDocument.Load(FILENAME);
XElement x_ScalarWebAPI_DeviceInfo = doc.Descendants().Where(x => x.Name.LocalName == "X_ScalarWebAPI_DeviceInfo").FirstOrDefault();
XNamespace ns = x_ScalarWebAPI_DeviceInfo.Name.Namespace;

The issue is indeed the Element or Elements methods only search the direct child elements. You can use Decendants() but you will get a collection, so you have to do First(expression) to het a single one.
But in the expression you can use .Name.LocalName to skip the whole namespace thing and look for just the name of the element.
For this question:
XDocument xDoc = XDocument.Parse(xml_text);
XElement x_ScalarWebAPI_DeviceInfo = doc.Descendants().First(x.Name.LocalName == "X_ScalarWebAPI_DeviceInfo");

Issues Querying XML with Namespace

I am attempting to consume a Rest service that returns an XML response. I have successfully made the get request, my problem is processing the response. The response includes a namespace that seems to be messing up my linq query. I have tried almost everything I can think of userNames always comes up empty. Any help would be greatly appreciated and could possibly save my sanity.
<?xml version="1.0" encoding="UTF-8"?>
<tsResponse xmlns="http://tableausoftware.com/api" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://tableausoftware.com/api http://tableausoftware.com/api/ts-api-2.0.xsd">
<users>
<user id="c9274ce9-0daa-4aad-9bd2-3b1d6d402119" name="_DevITTemplate" role="Unlicensed" publish="false" contentAdmin="false" lastLogin="" externalAuthUserId=""/>
string usersList =
request.DownloadString("http://bshagena-sandbox/api/2.0/sites/b4126fe9-d7ee-4083-88f9- a5eea1f40416/users/");
request.Dispose();
XDocument xd;
XElement users;
XNamespace ns = "http://tableausoftware.com/api";
xd = XDocument.Parse(usersList);
users = xd.Root.Elements().First();
var userNames = from a in users.Descendants(ns +"users")
select (string)a.Attribute("name").Value;

It is your user element which contains attribute name, not the names wrapper element. Adjust your xpath accordingly: (Your use of the XNamespace is fine)
var userNames = from a in users.Descendants(ns + "user")
select a.Attribute("name").Value;
Minor - Attribute.Value is already a string - no need to cast it :)

Here is what I did and it seemed to work. Sorry for all the comments. I am sure this is not the most efficient way to do this. I hope this helps someone else losing their mind over the same issue.
// Sends get request and stores response as a string
string usersList =
request.DownloadString("http://<serverName>/api/2.0/sites/b4126fe9-d7ee-4083-88f9-a5eea1f40416/users/");
// declares an XML document object
XDocument xd;
// Declares and XML element object
XElement users;
// Declares a stupid XML namespace object
XNamespace ns = "http://tableausoftware.com/api";
// Sets document to value of string
xd = XDocument.Parse(usersList);
// Sets the element to value of the first node of the xml document
users = xd.Root.Elements().First();
// Creates an array and queries elements based on attribute of name
var userNames = from a in users.Elements(ns + "user")
select (string)a.Attribute("name").Value;

Cannot parse xml from Yahoo! Fantasy Sports with c#

I did some searching around the web and could not find the cause of my problem so I apologize if that has already been asked in another form I just did not understand.
My problem is that I am trying to parse the XML retrieved from Yahoo! Fantasy Sports but nothing seems to be working.
I have converted the XML I received (using a GET request with my credentials) into a string. Here it is for evaluation.
<?xml version="1.0" encoding="UTF-8" ?>
- <fantasy_content xml:lang="en-US" yahoo:uri="http://fantasysports.yahooapis.com/fantasy/v2/game/223/players" xmlns:yahoo="http://www.yahooapis.com/v1/base.rng" time="5489.1560077667ms" copyright="Data provided by Yahoo! and STATS, LLC" refresh_rate="60" xmlns="http://fantasysports.yahooapis.com/fantasy/v2/base.rng">
- <game>
<game_key>223</game_key>
<game_id>223</game_id>
<name>Football PLUS</name>
<code>pnfl</code>
<type>full</type>
<url>http://football.fantasysports.yahoo.com/f2</url>
<season>2009</season>
- <players count="25">
- <player>
<player_key>223.p.8261</player_key>
<player_id>8261</player_id>
- <name>
<full>Adrian Peterson</full>
<first>Adrian</first>
<last>Peterson</last>
<ascii_first>Adrian</ascii_first>
<ascii_last>Peterson</ascii_last>
</name>
<editorial_player_key>nfl.p.8261</editorial_player_key>
<editorial_team_key>nfl.t.16</editorial_team_key>
<editorial_team_full_name>Minnesota Vikings</editorial_team_full_name>
<editorial_team_abbr>Min</editorial_team_abbr>
- <bye_weeks>
<week>9</week>
</bye_weeks>
<uniform_number>28</uniform_number>
<display_position>RB</display_position>
- <headshot>
<url>http://l.yimg.com/iu/api/res/1.2/7gLeB7TR77HalMeJv.iDVA--/YXBwaWQ9eXZpZGVvO2NoPTg2MDtjcj0xO2N3PTY1OTtkeD0xO2R5PTE7Zmk9dWxjcm9wO2g9NjA7cT0xMDA7dz00Ng--/http://l.yimg.com/j/assets/i/us/sp/v/nfl/players_l/20120913/8261.jpg</url>
<size>small</size>
</headshot>
<image_url>http://l.yimg.com/iu/api/res/1.2/7gLeB7TR77HalMeJv.iDVA--/YXBwaWQ9eXZpZGVvO2NoPTg2MDtjcj0xO2N3PTY1OTtkeD0xO2R5PTE7Zmk9dWxjcm9wO2g9NjA7cT0xMDA7dz00Ng--/http://l.yimg.com/j/assets/i/us/sp/v/nfl/players_l/20120913/8261.jpg</image_url>
<is_undroppable>1</is_undroppable>
<position_type>O</position_type>
- <eligible_positions>
<position>RB</position>
</eligible_positions>
<has_player_notes>1</has_player_notes>
</player>
- <player>
</players>
</game>
</fantasy_content>
The two methods I have tried are these (PLEASE NOTE: "xmlContent" is the string that contains the XML listed above):
1.)
XDocument chicken = XDocument.Parse(xmlContent);
var menus = from menu in chicken.Descendants("name")
select new
{
ID = menu.Element("name").Value,
};
and
2.)
byte[] encodedString = Encoding.UTF8.GetBytes(xmlContent);
MemoryStream ms = new MemoryStream(encodedString);
XmlDocument doc = new XmlDocument();
doc.Load(ms);
foreach (XmlNode row in doc).SelectNodes("//fantasy_content"))
{}
Basically, I get no results enumerated. I have a feeling I am missing some key steps here though. Any help is greatly appreciated. Thank you all.
UPDATE:
As per the awesome suggestions I received, I tried three more things. Since it is not working still, I did not listen very well. :) Actually, that is semi-accurate, please bear with my newbie attempt at working with XML here as I really am thankful for the responses. Here is how I am screwing up the great suggestions, can you offer another tip on what I missed? Thank you all again.
As per Jon Skeet's suggestion (this yields no results for me):
1.) XNamespace ns = "http://fantasysports.yahooapis.com/fantasy/v2/base.rng";
XDocument chicken = XDocument.Parse(xmlContent);
var menus = from menu in chicken.Descendants(ns + "fantasy_content")
select new
{
ID = menu.Element("name").Value,
};
As per the second suggestion (this throws me an error):
2.) var result = XElement.Load(xmlContent).Descendants().Where(x => x.Name.LocalName == "name");
As per the combinations of suggesting I need to identify the namespace and Yahoo! guide at: http://developer.yahoo.com/dotnet/howto-xml_cs.html
3.) xmlContent = oauth.AcquirePublicData(rtUrl, "GET");
byte[] encodedString = Encoding.UTF8.GetBytes(xmlContent);
MemoryStream ms = new MemoryStream(encodedString);
XmlDocument doc = new XmlDocument();
doc.Load(ms);
XmlNamespaceManager ns = new XmlNamespaceManager(doc.NameTable);
ns.AddNamespace("fantasy_content", "http://fantasysports.yahooapis.com/fantasy/v2/base.rng");
XmlNodeList nodes = doc.SelectNodes("/name", ns);
foreach (XmlNode node in nodes)
{
}

This is what's tripping you up:
xmlns="http://fantasysports.yahooapis.com/fantasy/v2/base.rng"
You're asking for elements in the unnamed namespace - but the elements default to the namespace shown above.
It's easy to fix that in LINQ to XML (and feasible but less simple in XmlDocument)
XNamespace ns = "http://fantasysports.yahooapis.com/fantasy/v2/base.rng";
var menus = chicken.Descendants(ns + "name")
...
Note that in your original method you're actually looking for name elements within the name elements - that's not going to work, but the namespace part is probably enough to get you going.
EDIT: It's not clear why you're using an anonymous type at all, but if you really want all the name element values from the document as ID properties in anonymous type instances, just use:
XNamespace ns = "http://fantasysports.yahooapis.com/fantasy/v2/base.rng";
var menus = chicken.Descendants(ns + "name")
.Select(x => new { ID = x.Value });
Note that there's no need to use Descendants(ns + "fantasy_content") as that's just selecting the root element.

Element name consists of two parts: xmlns(namespace) and localname. If xmlns is absent, name is equal to local name. So, you have to create name with namespace or ignore it
You can ignore namespace in your LINQ, just use LocalName
var result = XElement.Load(#"C:\fantasy_content.xml")
.Descendants()
.Where(x => x.Name.LocalName == "name")
.ToList();

Can not get address_component element from Google Geocoding API XML output with LINQ

I try to get some data from Google Geocoding API with C# and ASP.net. But I have trouble with XML responce. I get valid XML and I can get evry element besides "address_component" element. (XML looks like this : http://maps.googleapis.com/...)
/* data is a string with XML from Google server */
XDocument receivedXml = new XDocument();
receivedXml = XDocument.Parse(data);
XName address = XName.Get("address_component");
var root = reciviedXml.Root; //returns corect XElement
XElement result = root.Element("result"); //returns corect XElement
IEnumerable<XElement> components = result.Elements("address_component"); //returns empty collection
This is another way, I'have tried it to with the same result.
var results = reciviedXml.Descendants("address_component");
And when I try to get some descendant of like:
var types = receivedXml.Descendants("type");
It's the empty collection to. But another elements in "result" tag (like the "location" tag)I can get successfully.
Thanks for any advice.

The following:
var receivedXml = XDocument.Load("http://maps.googleapis.com/maps/api/geocode/xml?latlng=49.1962253,16.6071422&sensor=false");
Console.WriteLine(receivedXml.Root.Element("result").Elements("address_component").Count());
Console.WriteLine(receivedXml.Descendants("address_component").Count());
Writes 10 and 28 respectively. Make sure you are using the same instance - in your question you usereceivedXml as well as reciviedXml so you may have two instances XDocument and one of these may contain different data. Also you don't need to instantiate XDocument as XDocument.Parse() will do it for you (and the address variable seems to be unused)