Develop Reference

Navigate between XML Elements with Same Attribute

I'm working on a C#/ASP.Net project.
Let's say this is an xml document:
parent1
child1 attributeA
child2 attributeA
parent2
child3 attributeA
child4 attributeB
I want to navigate with next and previous buttons between anything with attributeA, so if I'm at parent1/child2, next would be parent2/child3 and previous would be parent1/child1.
I can create a new XML Document, I can load it, and I can get the current node, but I don't know about next and previous.
How can I do that? Haven't done xpaths in a while. A LONG while. I looked around here for something similar but either it's not there or I can't find it.
Can anyone help?

The MSDN has a nice article about XPaths with great examples
But this code should give you all the nodes that have attributeA regardless of where they are nested in the XML:
var doc = new XmlDocument();
doc.Load(#"C:\path\to\file.xml");
XmlNodeList nodes = doc.SelectNodes("//*[#attributeA]");
foreach (var node in nodes)
{
// your code here
}
The path //*[#attributeA] boils down to:
// "one or more levels deep"
* "any element"
[#attributeA] "with attribute 'attributeA'"

Get specific data from XML document

I have xml document like this:
<level1>
<level2>
<level3>
<attribute1>...</attribute1>
<attribute2>false</attribute2>
<attribute3>...</attribute3>
</level3>
<level3>
<attribute1>...</attribute1>
<attribute2>true</attribute2>
<attribute3>...</attribute3>
</level3>
</level2>
<level2>
<level3>
<attribute1>...</attribute1>
<attribute2>false</attribute2>
...
...
...
I'm using c#, and I want to go thru all "level3", and for every "level3", i want to read attribute2, and if it says "true", i want to print the corresponding attribute3 (can be "level3" without these attributes).
I keep the xml in XmlDocument.
Then I keep all the "level3" nodes like this:
XmlNodeList xnList = document.SelectNodes(String.Format("/level1/level2/level3"));
(document is the XmlDocument).
But from now on, I don't know exactly how to continue. I tried going thru xnList with for..each, but nothing works fine for me..
How can I do it?
Thanks a lot

Well I'd use LINQ to XML:
var results = from level3 in doc.Descendants("level3")
where (bool) level3.Element("attribute2")
select level3.Element("attribute3").Value;
foreach (string result in results)
{
Console.WriteLine(result);
}
LINQ to XML makes all kinds of things much simpler than the XmlDocument API. Of course, the downside is that it requires .NET 3.5...
(By the way, naming elements attributeN is a bit confusing... one would expect attribute to refer to an actual XML attribute...)

You can use LINQ to XML and reading this is a good start.

You can use an XPath query. This will give you a XmlNodeList that contains all <attribute3> elements that match your requirement:
var list = document.SelectNodes("//level3[attribute2 = 'true']/attribute3");
foreach(XmlNode node in list)
{
Console.WriteLine(node.InnerText);
}
You can split the above xpath query in three parts:
"//level3" queries for all descendant elements named <level3>.
"[attribute2 = 'true']" filters the result from (1) and only keeps the elements where the child element <attribute2> contains the text true.
"/attribute3" takes the <attribute3> childnode of each element in the result of (2).

Relative XPath selection using XmlNode (c#)

Say i have the following xml file:
<a>
<b>
<c></c>
</b>
<b>
<c></c>
</b>
</a>
var nodes = doc.SelectNodes("/a/b");
will select the two b nodes.
I then loop these two nodes suchas:
foreach (XmlNode node in nodes) { }
However, when i call node.SelectNodes("/a/b/c"); It still returns both values and not just the descendants.
Is it possible to select nodes only descening from the current node?

In the foreach loop, you already know that node is a /a/b in the original document - so to get just its c children simply use a relative xpath:
node.SelectNodes("c")

You can use node.SelectSingleNode("C");

/a/b[1]/c
For intance gets the nodelist of all the children of the first b that have the tagname c.
To get the first c as a singleton nodelist use /a/b[1]/c[1]. /a/b/c[1] again returns a nodelist of multiple nodes.
SelectSingleNode is probably misleading, as far as I know, XPath always returns a nodelist, which can contain optionally one node (or even be empty).
//c[1] just selects the first c in the document.

Read XMLDocument node without reading its child nodes in C#

Sample XML
<A>
<B>
<B1/>
<B2/>
<B3/>
<B4/>
<B5/>
</B>
<C>
<C1/>
<C2/>
<C3/>
<C4/>
<C5/>
</C>
</A>
Query:
C#
When I read the the child nodes of A it retuns nodes B & C with their child nodes.
Is there any possibility so that I can get only B & C without their respective child nodes
I need to populate the tree with this type of xml & the xml file is quite big. so I need to load the childs at the time of expanding any node
Requirement is
Suppose I try to expand A node the I want only B & C,
If I expand B then I want B1 to B5

Use a XmlReader. XmlDocument by design has to load the whole Xml document into memory.

if you use java, you can implement a SAX Handler building your DOM and ignoring the children.

It's a badly worded question so I'm not entirely sure what you are trying to do but if you just want all the child nodes of the root (A) then use an XmlDocument with XPath like this:
XmlDocument doc = new XmlDocument();
doc.Load(xmlFile);
XmlNodeList nodes = doc.SelectNodes("/A/*");
foreach(XmlNode node in nodes){
//DO STUFF
}

if i understand the question right, u need to get children of the node without getting their children. this can be done by xquery
(child::*)
so if u apply it in A node it will give B and C. if u apply it in B then it will give B1-B5.

How do I convert an XmlNodeList into a NodeSet to use within XSLT?

I've got a XmlNodeList which I need to have it in a format that I can then re-use within a XSLT stylesheet by calling it from a C# extension method.
Can anyone help? I have read that it might have something to do with using a XPathNavigator but I'm still a bit stuck.

I had to solve this issue myself a couple of years ago. The only way I managed it was to create an XML fragment containing the nodes in the node list and then passing in the children of the fragment.
XsltArgumentList arguments = new XsltArgumentList();
XmlNodeList nodelist;
XmlDocument nodesFrament = new XmlDocument();
XmlNode root = nodesFragment.CreateElement("root");
foreach (XmlNode node in nodeList)
{
root.AppendChild(node);
}
nodesFragment.AppendChild(root);
arguments.AddParam("argumentname", string.Empty, nodesFragment.CreateNavigator().SelectChildren(XPathNodeType.All));
Then you need to make sure you have the corresponding argument in your XSLT, of course.
Note that you probably don't need the additional XmlDocument. You could just call CreateNavigator() on the root XmlNode instance and use your existing XmlDocument for creating the element (I wrote this code some time ago and I've learned more since then - but I know the code above works, I haven't tried any alternatives).

The note at the end was the most useful, I had infact transformed the XmlNodeList into a XmlDocument already so could just use the Navigator on there and create it as a XPathNodeIterator.
Thanks for you help!

Didn't succeed with the answer provided before.
Using AppendChild() to add previously selected nodes of XmlNodeList to a new document resulted in exception on trying to append nodes originating from a different document context. Several trials to fix this included adding my custom default namespace selected nodes in list are bound to. Finally I dropped the approach completely and switched the way I select nodes into XmlNodeList instances.
Instead of
myXmlNode.SelectNodes( xpath, nsmgr )
I'm using
myXmlNode.CreateNavigator().Select( xpath, nsmgr )
to get an XPathNodeIterator instead of XmlNodeList. The resulting XPathNodeIterator of second code is now properly added as parameter value to XsltArgumentsList.