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

I'm unable to extract the Data from this XML

I'm currently working on a small weather application in C#. To do this, I need to extract data from this xml file: http://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20geo.places%20where%20text%3D%22london%22&format=xml
In this specific case I need the value of the first /query/results/place/woeid node. I've been looking around and tried many different methods, but didn't manage to get any values with any of those. My current code looks like this:
string query = String.Format("http://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20geo.places%20where%20text%3D%22london%22&format=xml");
XmlDocument xml = new XmlDocument();
xml.Load(query);
XmlNodeList nodeList = wData.DocumentElement.SelectNodes("/query/results/place");
foreach (XmlNode node in nodeList)
{
return node.SelectSingleNode("woeid").InnerText;
}
return "NO WOEID FOUND!";
I'm just starting to learn C# so I might do some stupid mistakes. Still, I would really appreciate any kind of help.

You can use XDocument
string query = String.Format("http://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20geo.places%20where%20text%3D%22london%22&format=xml");
XDocument xml = XDocument.Load(query);
XNamespace ns = "http://where.yahooapis.com/v1/schema.rng";
var woeid = xml.Element("query").Element("results").Elements(ns + "place").FirstOrDefault().Element(ns +"woeid").Value;
Make sure you check if there are any elements in the XDocuments

NodeList.SelectSingleNode() syntax

Having problems getting NodeList.SelectSingleNode() to work properly.
My XML looks like this:
<?xml version="1.0" encoding="ISO-8859-1" standalone="yes"?>
<inm:Results xmlns:inm="http://www.namespace.com/1.0">
<inm:Recordset setCount="18254">
<inm:Record setEntry="0">
<!-- snip -->
<inm:Image>fileName.jpg</inm:Image>
</inm:Record>
</inm:Recordset>
</inm:Results>
The data is a long series of <inm:Record> entries.
I open the doc and get create a NodeList object based on "inm:Record". This works great.
XmlDocument xdoc = new XmlDocument();
xdoc.Load(openFileDialog1.FileName);
XmlNodeList xRecord = xdoc.GetElementsByTagName("inm:Record");
I start looping through the NodeList using a for loop. Before I process a given entry, I want to check and see if the <inm:Image> is set. I thought it would be super easy just to do
string strImage = xRecord[i].SelectSingleNode("inm:Image").InnerText;
My thinking being, "For the XRecord that I'm on, go find the <inm:Image> value ...But this doesn't work as I get the exception saying that I need a XmlNameSpaceManager. So, I tried to set that up but could never get the syntax right.
Can someone show me how to use the correct XmlNameSpaceManager syntax in this case.
I've worked around the issue for now by looping through all of the childNodes for a given xRecord, and checking the tag once I loop around to it. I would like to check that value first to see if I need to loop over that <inm:Record> entry at all.

No need to loop through all the Record elements, just use XPath to specify the subset that you want:
XmlDocument xdoc = new XmlDocument();
xdoc.Load(openFileDialog1.FileName);
XmlNamespaceManager manager = new XmlNamespaceManager(xdoc.NameTable);
manager.AddNamespace("inm", "http://www.inmagic.com/webpublisher/query");
XmlNodeList nodes = xdoc.SelectNodes("/inm:Results/inm:Recordset/inm:Record[inm:Image != '']", manager);

Using the LINQ to XML libraries, here's an example for retrieving that said node's value:
XDocument doc = XDocument.Load(openFileDialog1.FileName);
List<XElement> docElements = doc.Elements().ToList();
XElement results = docElements.Elements().Where(
ele => ele.Name.LocalName == "Results").First();
XElement firstRecord = results.Elements().Where(
ele => ele.Name.LocalName == "Record").First();
XElement recordImage = firstRecord .Elements().Where(
ele => ele.Name.LocalName == "Image").First();
string imageName = recordImage.Value;
Also, by the way, using Hungarian notation for a type-checked language is overkill. You don't need to prepend string variables with str when it will always be a string.

XmlNamespaceManager nsMgr = new XmlNamespaceManager(xdoc.NameTable);
string strImage = xRecord[i].SelectSingleNode("inm:Image",nsMgr).InnerText;
Should do it.

Using this Xml library, you can get all the records that have an Image child element with this:
XElement root = XElement.Load(openFileDialog1.FileName);
XElement[] records = root.XPath("//Record[Image]").ToArray();
If you want to be sure that the Image child contains a value, it can be expressed like this:
XElement[] records = root.XPath("//Record[Image != '']").ToArray();

How can I address specific XML-Elements with C# when using namespaces?

I have to import XML-documents into a SQL-DB via C#. The XML has several namespaces.
I tried to address the specific elements I want wo import via XPath, but it broke due to the namespaces. Instead of
XmlDocument doc = new XmlDocument();
doc = XDocument.Load(Filename);
GENERATOR_INFO = doc.SelectSingleNode("ORDER/ORDER_HEADER/ORDER_INFO/GENERATOR_INFO").InnerText;
I write something like this:
XmlDocument doc = new XmlDocument();
doc = XDocument.Load(Filename);
XmlNamespaceManager nsmgr = new XmlNamespaceManager(doc.NameTable);
nsmgr.AddNamespace("openTrans", "http://www.opentrans.org/XMLSchema/2.1");
GENERATOR_INFO = doc.SelectSingleNode("//openTrans:GENERATOR_INFO", nsmgr).InnerText;
thus shortening the "path" to the element I need the Value of.
My question is: How can I address an element directly? In the XMl there are two elements called "ORDER_ID":
ORDER/ORDER_HEADER/ORDER_INFO/ORDER_ID
and
ORDER/ORDER_HEADER/CUSTOMER_ORDER_REFERENCE/ORDER_INFO
When using the syntax above I get only one element, with a loop/Linq I get both values but don't know, which one is which.
Is there an option to address the elements by there unique XPath despite the namespace?
regards
Jens

Found it :)
I have to reference every "step" of the XPath: ORDER_ID = doc.SelectSingleNode("//openTrans:ORDER_INFO/openTrans:ORDER‌​_ID", nsmgr).InnerText; resp. VIND_ORDER_ID = COR.SelectSingleNode("//openTrans:CUSTOMER_ORDER_REFERENCE/o‌​penTrans:ORDER_ID", nsmgr).InnerText

Can i create a XmlNamespaceManager object from the xml file i am about to read?

I have some c# code running on sharepoint that i use to check inside the xml of an infopath document to see if i should checking the document or discard the document.
The code is working fine for a couple of different form templates i have created but is failing on my latested one.
I have discovered that the XmlNamespaceManager i am creating contains the wrong diffinition for the "MY" namepsace.
I'll try to explain
I have this code to decalre my XmlNamespaceManager
NameTable nt = new NameTable();
NamespaceManager = new XmlNamespaceManager(nt);
// Add prefix/namespace pairs to the XmlNamespaceManager.
NamespaceManager.AddNamespace("xsi", "http://www.w3.org/2001/XMLSchema-instance");
NamespaceManager.AddNamespace("xhtml", "http://www.w3.org/1999/xhtml");
NamespaceManager.AddNamespace("dfs", "http://schemas.microsoft.com/office/infopath/2003/dataFormSolution");
NamespaceManager.AddNamespace("my", "http://schemas.microsoft.com/office/infopath/2003/myXSD/2010-07-14T13:45:59");
NamespaceManager.AddNamespace("xd", "http://schemas.microsoft.com/office/infopath/2003");`
I can then use the following line of code to search for the xml i am after
XPathNavigator nav = xml.CreateNavigator().SelectSingleNode("//my:HasSaved", NamespaceManager);
nav.Value then gets be the data i want.
This all works fine on a couple of my form templates. I ahve a new form template and have discovered that i need to use thi line instead
NamespaceManager.AddNamespace("my", "http://schemas.microsoft.com/office/infopath/2003/myXSD/2010-11-30T17:39:37");
The date is different.
My problem is that i cannot add this twice as only 1 set of forms will work.
So my question is. Is there a way i can generate the NamespaceManager object from the XML file as this is all contained in the header?
I have not been able to find a simple way round this.

I found a way of doing this. Instead of adding the "my" namespace it can be pulled from the XmlDocument object. This might just be a bit of luck that it works this way but i'm happy with it.
NamespaceManager.AddNamespace("my", formXml.DocumentElement.NamespaceURI
formXML is an XmlDocument created from the infopath XML

One option would be to try to load the xml node using the first namespace, if that doesn't give any results, call PushScope(), override the first namespace definition, select, etc...
var doc = new XmlDocument();
doc.LoadXml(#"<?xml version=""1.0""?>
<root xmlns:my=""http://schemas.microsoft.com/office/infopath/2003/myXSD/2010-11-30T17:39:37"" value=""1"">
<my:item>test</my:item>
</root>");
var nameTable = new NameTable();
var namespaceManager = new XmlNamespaceManager(nameTable);
namespaceManager.AddNamespace("xsi", "http://www.w3.org/2001/XMLSchema-instance");
namespaceManager.AddNamespace("xhtml", "http://www.w3.org/1999/xhtml");
namespaceManager.AddNamespace("dfs", "http://schemas.microsoft.com/office/infopath/2003/dataFormSolution");
namespaceManager.AddNamespace("my", "http://schemas.microsoft.com/office/infopath/2003/myXSD/2010-07-14T13:45:59");
namespaceManager.AddNamespace("xd", "http://schemas.microsoft.com/office/infopath/2003");
// n will be null since the namespace url doesn't match
var n = doc.SelectSingleNode("descendant::my:item", namespaceManager);
namespaceManager.PushScope();
namespaceManager.AddNamespace("my", "http://schemas.microsoft.com/office/infopath/2003/myXSD/2010-11-30T17:39:37");
// will work
n = doc.SelectSingleNode("descendant::my:item", namespaceManager);
namespaceManager.PopScope();
Another option is to parse the attributes in the header and look for any contained namespaces
foreach(XmlAttribute attribute in doc.DocumentElement.Attributes)
{
var url = namespaceManager.LookupNamespace(attribute.LocalName);
if(url != null && url != attribute.Value)
{
namespaceManager.RemoveNamespace(attribute.LocalName, url);
namespaceManager.AddNamespace(attribute.LocalName, attribute.Value);
}
}

You don't need to do anything like this. Just use "my2" or something for the second namespace. You then need the new namespace prefix for any nodes that use the new namespace, and use the old "my" namespace prefix for all the nodes that still use the old namespace.