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Count ChildElements of the same name, inside an XML Element, with XDocument

I have an XML file that looks like this -
<SST_SignageCompConfig>
<Items>
<Item>
<Index>0</Index>
<Type>1</Type>
<Duration>7</Duration>
<Name>Branding-Colours-for-business.jpg</Name>
</Item>
<Item>
<Index>1</Index>
<Type>1</Type>
<Duration>7</Duration>
<Name>Flower of Life Meditation - Copy.png</Name>
</Item>
</Items>
</SST_SignageCompConfig>
I need to count how many Item Elements there are within the Items Element.
ie how many images there are.
I'm using XDocument, so my XML file is loaded like this -
string configurationPath = System.IO.Path.Combine("C:\\SST Software\\DSS\\Compilations\\" + compName + #"\\Comp.cfg");
XDocument filedoc = XDocument.Load(configurationPath);
I've tried numerous variations of the following, with all returning a null object reference exception
foreach (var item in filedoc.Element("SST_SignageCompConfig").Element("Items").Element("Item").Nodes())
{
string name = filedoc.Element("SST_SignageCompConfig").Element("Items").Element("Item").Attribute("Name").ToString();
files.Append(name + "|");
}
I've found countless examples of how to count how many different child elements are within an element, but I need to know how many instances of the same element exist.
Can anyone point me in the right direction?

You can select all names like so:
var names = from item in filedoc.Descendants("Item")
select (string)item.Element("Name");
Or without the query syntax:
var names = filedoc.Descendants("Item").Elements("Name").Select(e => e.Value);
You can get only unique names by:
var uniqueNames = names.Distinct();

You're on the right track. Try finding out exactly which invocation is giving you the NullReferenceException. My guess is that it's the attempt to find:
.Element("SST_SignageCompConfig")
Which is your root. Try the following instead:
// note the difference between .Element and .Elements
var count = filedoc.Root.Element("Items").Elements("Item").Count();
You could also use XPath to help you nail down the navigation within your XDocument:
// returns the current top level element
var element = filedoc.Root.XPathSelectElement(".");
// If the returned element is "SST_SignageCompConfig", then:
var nextElement = filedoc.Root.XPathSelectElement("./Items")
// If the "." element is *not* "SST_SignageCompConfig", then try and locate where in your XML document that node is.
// You can navigate up with .Parent and down with .Element(s)
And so on.

How about:
var nav = fileDoc.CreateNavigator();
XPathNodeIterator navShape = nav.Select("/SST_SignageCompConfig/Items");
navShape.MoveNext()
var count = navShape.Count;

If your xml has only one Items element, this should do the trick:
filedoc.Descendants("Item")
.GroupBy(e => e.Element("Name")!=null? e.Element("Name").Value:String.Empty)
.Select(g => new
{
Name = g.Key,
Count = g.Count()
});

Because "Name" is an element and not an attribute of your xml structure.
can you try replacing this?
string name = filedoc.Element("SST_SignageCompConfig").Element("Items").Element("Item").Element("Name").ToString();

Poorly defined XML, get node and contents of all child nodes as string concat with spaces?

Here's some fantastic example XML:
<root>
<section>Here is some text<mightbe>a tag</mightbe>might <not attribute="be" />. Things are just<label>a mess</label>but I have to parse it because that's what needs to be done and I can't <font stupid="true">control</font> the source. <p>Why are there p tags here?</p>Who knows, but there may or may not be spaces around them so that's awesome. The point here is, there's node soup inside the section node and no definition for the document.</section>
</root>
I'd like to just grab the text from the section node and all sub nodes as strings. BUT, note that there may or may not be spaces around the sub-nodes, so I want to pad the sub notes and append a space.
Here's a more precise example of what input might look like, and what I'd like output to be:
<root>
<sample>A good story is the<book>Hitchhikers Guide to the Galaxy</book>. It was published<date>a long time ago</date>. I usually read at<time>9pm</time>.</sample>
</root>
I'd like the output to be:
A good story is the Hitchhikers Guide to the Galaxy. It was published a long time ago. I usually read at 9pm.
Note that the child nodes don't have spaces around them, so I need to pad them otherwise the words run together.
I was attempting to use this sample code:
XDocument doc = XDocument.Parse(xml);
foreach(var node in doc.Root.Elements("section"))
{
output += String.Join(" ", node.Nodes().Select(x => x.ToString()).ToArray()) + " ";
}
But the output includes the child tags, and is not going to work out.
Any suggestions here?
TL;DR: Was given node soup xml and want to stringify it with padding around child nodes.

Incase you have nested tags to an unknown level (e.g <date>a <i>long</i> time ago</date>), you might also want to recurse so that the formatting is applied consistently throughout. For example..
private static string Parse(XElement root)
{
return root
.Nodes()
.Select(a => a.NodeType == XmlNodeType.Text ? ((XText)a).Value : Parse((XElement)a))
.Aggregate((a, b) => String.Concat(a.Trim(), b.StartsWith(".") ? String.Empty : " ", b.Trim()));
}

You could try using xpath to extract what you need
var docNav = new XPathDocument(xml);
// Create a navigator to query with XPath.
var nav = docNav.CreateNavigator();
// Find the text of every element under the root node
var expression = "/root//*/text()";
// Execute the XPath expression
var resultString = nav.evaluate(expression);
// Do some stuff with resultString
....
References:
Querying XML, XPath syntax

Here is a possible solution following your initial code:
private string extractSectionContents(XElement section)
{
string output = "";
foreach(var node in section.Nodes())
{
if(node.NodeType == System.Xml.XmlNodeType.Text)
{
output += string.Format("{0}", node);
}
else if(node.NodeType == System.Xml.XmlNodeType.Element)
{
output += string.Format(" {0} ", ((XElement)node).Value);
}
}
return output;
}
A problem with your logic is that periods will be preceded by a space when placed right after an element.

You are looking at "mixed content" nodes. There is nothing particularly special about them - just get all child nodes (text nodes are nodes too) and join they values with space.
Something like
var result = String.Join("",
root.Nodes().Select(x => x is XText ? ((XText)x).Value : ((XElement)x).Value));

Linq to Xml question: struggling with a simple example

I am attempting to use XML for some simple formatting and embedded links. I'm trying to parse the XML using Linq to Xml, but I'm struggling with parsing a text "Value" with embedded elements in it. For example, this might be a piece of XML I want to parse:
<description>A plain <link ID="1">table</link> with a green hat on it.</description>
Essentially, I want to enumerate through the "Runs" in the Value of the description node. In the above example, there would be a text node with a value of "A plain ", followed by a "link" element, whose value is "table", followed by another text node whose value is " with the green hat on it.".
How do I do this? I tried enumerating the root XElement's Elements() enumeration, but that only returned the link element, as did Descendants(). DescendantNodes() did return all the nodes, but it also returned the subnodes of the link elements. In this case, a text node containing "table", in addition to the element that contained it.

You'll need to access the Nodes() method, check the XmlNodeType, and cast as appropriate to access each object's properties and methods.
For example:
var xml = XElement.Parse(#"<description>A plain <link ID=""1"">table</link> with a green hat on it.</description>");
foreach (var node in xml.Nodes())
{
Console.WriteLine("Type: " + node.NodeType);
Console.WriteLine("Object: " + node);
if (node.NodeType == XmlNodeType.Element)
{
var e = (XElement)node;
Console.WriteLine("Name: " + e.Name);
Console.WriteLine("Value: " + e.Value);
}
else if (node.NodeType == XmlNodeType.Text)
{
var t = (XText)node;
Console.WriteLine(t.Value);
}
Console.WriteLine();
}

XElement.Nodes() will enumerate only the top level child nodes.

Just use the Nodes() method on your description element.
var xmlStr = #"<description>A plain <link ID=""1"">table</link> with a green hat on it.</description>";
var descriptionElement = XElement.Parse(xmlStr);
var nodes = descriptionElement.Nodes();
foreach (var node in nodes)
Console.WriteLine("{0}\t\"{1}\"", node.NodeType, node);
Yields:
Text "A plain "
Element "<link ID="1">table</link>"
Text " with a green hat on it."

XML Lambda query in C#

I have an XmlDocument object and xml in the format:
<?xml version="1.0" encoding="utf-8"?>
<S xmlns="http://server.com/DAAPI">
<TIMESTAMP>2010-08-16 17:25:45.633</TIMESTAMP>
<MY_GROUP>
<GROUP>1 </GROUP>
<NAME>Amsterdam</NAME>
....
</MY_GROUP>
<MY_GROUP>
<GROUP>2 </GROUP>
<NAME>Ireland</NAME>
....
</MY_GROUP>
<MY_GROUP>
<GROUP>3 </GROUP>
<NAME>UK</NAME>
....
</MY_GROUP>
Using a Lambda expression (or Linq To XML if it's more appropriate) on the XmlDocument object how can i do the following:
get the text of a specific element, say the text of NAME where GROUP = 1
the value of the first occurance of the element "NAME"
Thanks a lot

Assuming you mean XDocument rather than XmlDcoument:
First question:
XNamespace ns = "http://server.com/DAAPI";
string text = (from my_group in doc.Elements(ns + "MY_GROUP")
where (int) my_group.Element(ns + "GROUP") == 1
select (string) my_group.Element(ns + "NAME")).First();
I didn't really understand the second question... what do yuo mean by "contains an element of that name"? Which name? And if you're checking for NAME being equal to a give name, wouldn't you already know that name? Did you perhaps mean the value of GROUP for a specific name? If so, it's easy:
XNamespace ns = "http://server.com/DAAPI";
int group = (from my_group in doc.Elements(ns + "MY_GROUP")
where (string) my_group.Element(ns + "NAME")
select (int) my_group.Element(ns + "GROUP")).First();
Both of these queries assume that the values do exist, and that each MY_GROUP element has a GROUP and NAME subelement. Please let us know if that's not the case.

I have used Linq to XML.
string input = "<?xml version=\"1.0\" encoding=\"utf-8\"?><S xmlns=\"http://server.com/DAAPI\"><TIMESTAMP>2010-08-16 17:25:45.633</TIMESTAMP><MY_GROUP><GROUP>1 </GROUP><NAME>Amsterdam</NAME>....</MY_GROUP><MY_GROUP><GROUP>2 </GROUP><NAME>Ireland</NAME>....</MY_GROUP><MY_GROUP><GROUP>3 </GROUP><NAME>UK</NAME>....</MY_GROUP></S>";
var doc = XDocument.Parse(input);
XNamespace ns = "http://server.com/DAAPI";
//The first question
var name = (from elem in doc.Root.Elements(ns + "MY_GROUP")
where elem.Element(ns + "GROUP") != null //Checks whether the element actually exists - if you KNOW it does then it can be removed
&& (int)elem.Element(ns + "GROUP") == 1 //This could fail if not an integer - insure it is if nessasary
select (string)elem.Element(ns + "NAME")).SingleOrDefault();

I understood only your first question. Here you are for the first:
var xmlSource = myGroup.Load(#"../../MyGroup.xml");
var q = from c in xmlSource.myGroup
where c.group = 1
select c.name;

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");