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

Update XML Document in WPF C#

I have got problems to update a XML Document.
<?xml version="1.0" encoding="utf-16"?>
<test>
<settings server="1" />
</test>
For example I want to update the "1".
I tried like this:
XmlDocument doc = new XmlDocument();
doc.Load(path);
doc.SelectSingleNode("test/settings/server").InnerText = "2"
doc.Save(path);
I think this should be easy to solve, but I am really a blockhead.
UPDATE:
I have tried your solutions and they work with the given example.
Thank you to all of you!
But in the given XML, there is a weird structure, I got problems with:
<?xml version="1.0" encoding="utf-16"?>
<test>
<settings server="1" />
<settings config="999" />
</test>
With this structure none of your solutions work and i always get a "System.NullReferenceException" if I try to change the '999' of config.
I only can access the '1' of server.
Sorry, I didn't expected this and tried to keep the example as easy as possible.

You can do this with
var path = #"C:\users\bassie\desktop\test.xml";
var doc = new XmlDocument();
doc.Load(path);
var settings = doc.SelectSingleNode("test/settings");
settings.Attributes["server"].Value = "2";
doc.Save(path);
InnerText would be used if you wanted to update settings to read something like:
<settings server="1"> 2 </settings>
Where you are trying to update an attribute of the settings element.
Regarding your update, you can replace doc.SelectSingleNode with doc.SelectNodes like so:
var settings = doc.SelectNodes("test/settings");
This will select all the available settings elements under test.
Then when setting the attribute you just provide the index of the element you want to target, e.g.:
settings[0].Attributes["server"].Value = "2";
to update the value of server, or
settings[1].Attributes["config"].Value = "000";
to update the value of config.
However
I think your best best here would be to use System.Xml.Linq, so that you can select the correct settings element by attribute name:
var document = XDocument.Load(path);
var attributeName = "server";
var element = document.Descendants("settings")
.FirstOrDefault(el => el.Attribute(attributeName) != null);
That code gets all settings elements (Descendants) in the document, and then selects the first one where the attributeName ("server" in this case) is not null.
This of course relies on the fact that each attribute only appear once (i.e. you can't have multiple settings elements with the "server" attribute), as it uses the FirstOrDefault selector meaning it will only return 1 element.
Hope this helps

server is an attribute
var doc = new XmlDocument();
doc.Load(path);
doc.SelectSingleNode("test/settings").Attributes["server"].Value = "2"
doc.Save(path);

Try this:
XmlDocument doc = new XmlDocument();
doc.Load(path);
XmlNode root = doc.DocumentElement;
XmlNode myNode = root.SelectSingleNode("test/settings");
myNode.Attributes["server"].Value = "2";
doc.Save(path);

Or LINQ to XML
var document = XDocument.Load(path);
document.Descendants("settings").First().Attribute("server").Value = "2";
document.Save(path);

LINQ TO XML retrieving Child Element Value

I have the following XML
<ABC xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://ns.hr-xml.org/2007-04-15">
<ReceiptId>
<IdValue>123</IdValue>
</ReceiptId>
<ClientOrderId>
<IdValue>345</IdValue>
</ClientOrderId>
<AccessPoint>
<Description>My Description</Description>
</AccessPoint>
<ABCStatus>
<Status>Error</Status>
<Details>ERRORS:
Talent is already in an active process for this opening.
</Details>
<StatusDate>2015-08-05</StatusDate>
</ABCStatus>
</ABC>
I am trying to retrieve the element value 345 nested in IdValue and ClientOrderId
I have used the Linq to xml code in C# to retrieve the value with no luck
XDocument XMLResults = XDocument.Parse(sResult);
var sClientOrderID =
from nodeAElem in XMLResults.Root.Elements("ABC")
from nodeA1Elem in nodeAElem.Elements("ClientOrderId")
from nodeA11Elem in nodeA1Elem.Elements("IdValue")
select nodeA11Elem.Value;
also need to retrieve the Status Elements value which is Error for the above xml.
Any help is greatly appreciated

Your XML document is using a namespace, you have to use it in your query to make it work.
Root already brings you to ABC element, so you don't have to call Elements("ABC")
You're looking for single value, so you probably want to use Element instead of Elements.
var ns = (XNamespace)"http://ns.hr-xml.org/2007-04-15";
var sClientOrderID = (int)XMLResults.Root
.Element(ns + "ClientOrderId")
.Element(ns + "IdValue");

XDocument LINQ search based on attribute

I have an XML document which I load from the disk
XDocument events = XDocument.Load("Content/GameData/events.xml");
The contents of this xml are the following:
<?xml version='1.0' encoding='UTF-8'?>
<Events>
<level1>
<NarrationEvent code="lvl1_fridge">
I can't even remember when I last ate.
I am not hungry though.
</NarrationEvent>
<NarrationEvent code="lvl1_tv">
Why do I even have a TV?
Oh right, I use it as a screen for my laptop.
</NarrationEvent>
<NarrationEvent code="lvl1_bed">
Oh man, I am beat.
</NarrationEvent>
<NarrationEvent code="lvl1_computer">
Oh, look at that. The project has been compiled.
</NarrationEvent>
</level1>
<level2>
</level2>
<level3>
</level3>
<level4>
</level4>
<cave>
</cave>
</Events>
I use this code here supposedly select the appropriate NarrationEvent element, based on its attribute "code"
IEnumerable<XElement> v =
(from narrationEvent in events.Elements("NarrationEvent")
where (string)narrationEvent.Attribute("code") == code
select narrationEvent);
foreach (XElement page in v)
{
//Console.WriteLine("ff");
narration.Add(page.Value);
}
This returns nothing, my XElement Ienumerable is empty. I used breakpoints and the code value is passed to this method just fine. e.g. "lvl1_bed"
What is wrong with this code?

You can use the Descendants-Method to get your NarrationEvent-Element. I have updated your code accordingly.
IEnumerable<XElement> v = from narrationEvent in events.Descendants("NarrationEvent")
where narrationEvent.Attribute("code").Value == code
select narrationEvent;

Load info from xml, save related (changed) info using c#

Friends,
My school project is having an xml data file:
<patients>
<patient>
<regNo>2012/Mar/003</regNo>
<name>Jhon</name>
<add>Somewhere</add>
<mobile>0000</mobile>
.
.
.
<stay>2</stay>
<costofroom>100</costofroom>
<total>200</total>
</patient>
</patients>
My Windowsform "EditPatients_Load" is able to fetch all info of patient Jhon, and now let's assume that the Admin needs to change some information in the form & resubmit.
Then how to write back all values to Jhon's account in the same xml
file????
I'm not able to makeup the logical code, even if I check the node if (patients.paptient.name = "nameComboBox.text").... how to make sure that I'm writing other values on proper place?
Rgrdz,

Try this:
//string xml =
//#"<patients><patient><regNo>2012/Mar/003</regNo><name>Jhon</name><add>Somewhere
//</add><mobile>0000</mobile><stay>2</stay><costofroom>100</costofroom><total>200</total>
//</patient></patients>";
XDocument xmlDoc = XDocument.Load(#"c:\abc.xml");
var items = (from item in xmlDoc.Descendants("patient")
where item.Element("name").Value == "Jhon"
select item);
if (items.Count() > 0)
{
var item = items.First();
item.SetElementValue("add", "New New Address");
xmlDoc.Save(#"c:\abc.xml", SaveOptions.None);
}
You can get single element using
var item = (from item in xmlDoc.Descendants("patient")
where item.Element("name").Value == "Jhon"
select item).FirstOrDefault();
then update it using SetElementValue() method.
//Updated Xml
<?xml version="1.0" encoding="utf-8"?>
<patients>
<patient>
<regNo>2012/Mar/003</regNo>
<name>Jhon</name>
<add>New Address</add>
<mobile>0000</mobile>
<stay>2</stay>
<costofroom>100</costofroom>
<total>200</total>
</patient>
</patients>
Reference:
Update XML with C# using Linq

I would take the xml serialization/deserialization route to solve this:
http://support.microsoft.com/kb/815813
How to Deserialize XML document
That way you can work with objects and not have to parse xml files manually.

If you're using .NET 3.5 onward you can use the XDocument class like the following. I'm assuming your content is in a .xml file.
XDocument xdoc = XDocument.Load(#"C:\Tmp\test.xml");
//this would ensure you get the right node and set its text content/value
xdoc.Element("patients")
.Element("patient").Element("add").Value = "some new address?";
xdoc.Save(#"C:\Tmp\test.xml");
The file test.xml would change to:
<patients>
<patient>
<regNo>2012/Mar/003</regNo>
<name>Jhon</name>
<add>some new address?</add>
<mobile>0000</mobile>
<stay>2</stay>
<costofroom>100</costofroom>
<total>200</total>
</patient>
</patients>