Develop Reference

Sequence contains no elements when trying to grab xml node value from xml string

Please read the code bellow. There I am trying to grab all elements under the <GetSellerListResponse> node, then my goal is to grab TotalNumberOfPages value (currently it's 9 as you can see in the XML).
But my problem is I am getting an error:
System.InvalidOperationException: 'Sequence contains no elements'
Error screenshot is attached for better understanding. Can you tell me what's wrong the way I am trying to grab all elements? Also if possible can you tell how I can grab that 9 from TotalNumberOfPage?
Thanks in advance
C#:
var parsedXML = XElement.Parse(xml);
var AllElements = parsedXML.Descendants("GetSellerListResponse")
.Where(x => x.Attribute("xmlns").Value.Equals("urn:ebay:apis:eBLBaseComponents"))
.First();
XML:
<?xml version="1.0" encoding="UTF-8"?>
<GetSellerListResponse xmlns="urn:ebay:apis:eBLBaseComponents">
<Timestamp>2018-06-20T17:26:29.518Z</Timestamp>
<Ack>Success</Ack>
<Version>1059</Version>
<Build>E1059_CORE_APISELLING_18694654_R1</Build>
<PaginationResult>
<TotalNumberOfPages>9</TotalNumberOfPages>
</PaginationResult>
</GetSellerListResponse>

EDIT: your mistake is the usage of XElement: it is searching for matching elements in the children of <GetSellerListResponse>; that's why you are not getting any result. Change XElement.Parse(xml); to XDocument.Parse(xml);, then the following snippets will work.
You could simply check for the local name:
var AllElements = parsedXML.Descendants().First(x => x.Name.LocalName == "GetSellerListResponse");
I would suggest to use XDocument instead of XElement for parsedXML, because you could shorten the above query to var AllElements = parsedXML.Root;
Another thing you could try is prepending the namespace:
XNamespace ns = "urn:ebay:apis:eBLBaseComponents";
var AllElements = parsedXML.Descendants(ns + "GetSellerListResponse").First();
To answer the question "how to get the number of pages":
var pages = AllElements.Element(ns + "PaginationResult").Element(ns + "TotalNumberOfPages").Value;

I would suggest using the XmlDocument class from System.Xml.
Try the code below:
XmlDocument doc = new XmlDocument();
doc.LoadXml("<GetSellerListResponse xmlns=\"urn:ebay:apis:eBLBaseComponents\"><Timestamp>2018-06-20T17: 26:29.518Z</Timestamp><Ack>Success</Ack><Version>1059</Version><Build>E1059_CORE_APISELLING_18694654_R1</Build><PaginationResult><TotalNumberOfPages>9</TotalNumberOfPages></PaginationResult></GetSellerListResponse>");
XmlNodeList nodeList = doc.GetElementsByTagName("TotalNumberOfPages");
In this case, your nodeList will have just the one element for TotalNumberOfPages and you can access the value by checking
nodeList.FirstOrDefault().InnerText

how to take a specific child node value in xml using C#

I have an xml schema like below
<library>
<book>
<id>1</id>
<name>abc</name>
<read>
<data>yes</data>
<num>20</num>
</read>
</book>
<book>
<id>20</id>
<name>xyz</name>
<read>
<data>yes</data>
<num>32</num>
</read>
</book>
</library>
Now if the id is 20 i need to take the value of tag <num> under <read>
I done the code as below
var xmlStr = File.ReadAllText("e_test.xml");
var str = XElement.Parse(xmlStr);
var result = str.Elements("book").Where(x => x.Element("id").Value.Equals("20")).ToList();
this give the whole <book> tag with id 20. From this how can I extract only the value of tag <num>.
ie is i need to get the value 32 in to a variable

Before you try to extract the num value, you need to fix your Where clause - at the moment you're comparing a string with an integer. The simplest fix - if you know that your XML will always have an id element which has a textual value which is an integer - is to cast the element to int.
Next, I'd use SingleOrDefault to make sure there's at most one such element, assuming that's what your XML document should have.
Then you just need to use Element twice to navigate down via read and then num, and cast the result to int again:
// Or use XDocument doc = ...; XElement book = doc.Root.Elements("book")...
XElement root = XElement.Load("e_test.xml")
XElement book = root.Elements("book")
.Where(x => (int) x.Element("id") == 20)
.SingleOrDefault();
if (book == null)
{
// No book with that ID
}
int num = (int) book.Element("read").Element("num");

If you're not dead set on using Linq, how about this XPath? XPath is probably more widely understood, and is really simple. The XPath to find your node would be:
/library/book[id=20]/read/num
Which you could use in C# thus:
var doc = new XmlDocument();
doc.LoadXml(myString);
var id = 20;
var myPath = "/library/book[id=" + id + "]/read/num";
var myNode = doc.SelectSingleNode(myPath);
Then you can do whatever you like with myNode to get its value etc..
Helpful reference:
http://www.w3schools.com/xsl/xpath_syntax.asp

Get certain xml node and save the value

Considering the following XML:
<Stations>
<Station>
<Code>HT</Code>
<Type>123</Type>
<Names>
<Short>H'bosch</Short>
<Middle>Den Bosch</Middle>
<Long>'s-Hertogenbosch</Long>
</Names>
<Country>NL</Country>
</Station>
</Stations>
There are multiple nodes. I need the value of each node.
I've got the XML from a webpage (http://webservices.ns.nl/ns-api-stations-v2)
Login (--) Pass (--)
Currently i take the XML as a string and parse it to a XDocument.
var xml = XDocument.Parse(xmlString);
foreach (var e in xml.Elements("Long"))
{
var stationName = e.ToString();
}

You can retrieve "Station" nodes using XPath, then get each subsequent child node using more XPath. This example isn't using Linq, which it looks like you possibly are trying to do from your question, but here it is:
XmlDocument xml = new XmlDocument();
xml.Load(xmlStream);
XmlNodeList stations = xml.SelectNodes("//Station");
foreach (XmlNode station in stations)
{
var code = station.SelectSingleNode("Code").InnerXml;
var type = station.SelectSingleNode("Type").InnerXml;
var longName = station.SelectSingleNode("Names/Long").InnerXml;
var blah = "you should get the point by now";
}
NOTE: If your xmlStream variable is a String, rather than a Stream, use xml.LoadXml(xmlStream); for line 2, instead of xml.Load(xmlStream). If this is the case, I would also encourage you to name your variable to be more accurately descriptive of the object you're working with (aka. xmlString).

This will give you all the values of "Long" for every Station element.
var xml = XDocument.Parse(xmlStream);
var longStationNames = xml.Elements("Long").Select(e => e.Value);

i am trying to select "description" from a rss feed if the title is equal to something

i am trying to select "description" from a rss feed if the title is equal to something.
in code i have this :
public static XmlDocument GetDefaultHoroscopesFeed(string StarSign){
xdoc.SelectSingleNode(string.Format("rss/channel/item/[title = '{0}']/description", StarSign));
xdoc.LoadXml(DefaultPageHoroscopeNode.InnerXml);
return xdoc;
}
but i keep getting this error : Expression must evaluate to a node-set.
Please help someone

You're not specifying a node name inbetween .../item/ and [title = ..., therefore you won't get back a valid node-set. Also, in RSS, the <title> node will not have a child node called <description>.
You need to change your XPath
"rss/channel/item/[title = '{0}']/description"
into
"rss/channel/item[title = '{0}']/description"
This will get you the <item> node that has a <title> node with the value StarSign and then retrieve its <description> node.
You could also do this using an XDocument and Linq to XML, like so:
XDocument xdoc = XDocument.Load(pathToRss);
XElement description = xdoc.Descendants("item")
.Where(i => i.Element("title").Value.Equals(StarSign))
.Select(i => i.Element("description"))
.FirstOrDefault();

XPathSelectElements returns null

Load function is already defined in xmlData class
public class XmlData
{
public void Load(XElement xDoc)
{
var id = xDoc.XPathSelectElements("//ID");
var listIds = xDoc.XPathSelectElements("/Lists//List/ListIDS/ListIDS");
}
}
I'm just calling the Load function from my end.
XmlData aXmlData = new XmlData();
string input, stringXML = "";
TextReader aTextReader = new StreamReader("D:\\test.xml");
while ((input = aTextReader.ReadLine()) != null)
{
stringXML += input;
}
XElement Content = XElement.Parse(stringXML);
aXmlData.Load(Content);
in load function,im getting both id and and listIds as null.
My test.xml contains
<SEARCH>
<ID>11242</ID>
<Lists>
<List CURRENT="true" AGGREGATEDCHANGED="false">
<ListIDS>
<ListID>100567</ListID>
<ListID>100564</ListID>
<ListID>100025</ListID>
<ListID>2</ListID>
<ListID>1</ListID>
</ListIDS>
</List>
</Lists>
</SEARCH>

EDIT: Your sample XML doesn't have an id element in the namespace with the nss alias. It would be <nss:id> in that case, or there'd be a default namespace set up. I've assumed for this answer that in reality the element you're looking for is in the namespace.
Your query is trying to find an element called id at the root level. To find all id elements, you need:
var tempId = xDoc.XPathSelectElements("//nss:id", ns);
... although personally I'd use:
XDocument doc = XDocument.Parse(...);
XNamespace nss = "http://schemas.microsoft.com/SQLServer/reporting/reportdesigner";
// Or use FirstOrDefault(), or whatever...
XElement idElement = doc.Descendants(nss + "id").Single();
(I prefer using the query methods on LINQ to XML types instead of XPath... I find it easier to avoid silly syntax errors etc.)
Your sample code is also unclear as you're using xDoc which hasn't been declared... it helps to write complete examples, ideally including everything required to compile and run as a console app.

I am looking at the question 3 hours after it was submitted and 41 minutes after it was (last) edited.
There are no namespaces defined in the provided XML document.
var listIds = xDoc.XPathSelectElements("/Lists//List/ListIDS/ListIDS");
This XPath expression obviously doesn't select any node from the provided XML document, because the XML document doesn't have a top element named Lists (the name of the actual top element is SEARCH)
var id = xDoc.XPathSelectElements("//ID");
in load function,im getting both id and and listIds as null.
This statement is false, because //ID selects the only element named ID in the provided XML document, thus the value of the C# variable id is non-null. Probably you didn't test thoroughly after editing the XML document.
Most probably the original ID element belonged to some namespace. But now it is in "no namespace" and the XPath expression above does select it.

string xmldocument = "<response xmlns:nss=\"http://schemas.microsoft.com/SQLServer/reporting/reportdesigner\"><action>test</action><id>1</id></response>";
XElement Content = XElement.Parse(xmldocument);
XPathNavigator navigator = Content.CreateNavigator();
XmlNamespaceManager ns = new XmlNamespaceManager(navigator.NameTable);
ns.AddNamespace("nss", "http://schemas.microsoft.com/SQLServer/reporting/reportdesigner");
var tempId = navigator.SelectSingleNode("/id");

The reason for the null value or system returned value is due to the following
var id = xDoc.XPathSelectElements("//ID");
XpathSElectElements is System.xml.linq.XElment which is linq queried date. It cannot be directly outputed as such.
To Get individual first match element
use XPathSelectElement("//ID");
You can check the number of occurrences using XPathSelectElements as
var count=xDoc.XPathSelectElements("//ID").count();
you can also query the linq statement as order by using specific conditions
Inorder to get node value from a list u can use this
foreach (XmlNode xNode in xDoc.SelectNodes("//ListIDS/ListID"))
{
Console.WriteLine(xNode.InnerText);
}
For Second list you havnt got the value since, the XPath for list items is not correct