Develop Reference

Replace XML nodes with handlebars.js statements

I'm trying to build a simple way for non programmers to define loops and conditional logic within an XML file.
I've decided to use <Loop></Loop> and <Condition></Condition> tags to handle these cases. The idea being that the Loop and Condition tags will be replaced with handlebars.js #each and #if statements within the XML e.g
<Meeting>
<Loop Target="People">
<Person>
<Name>{{Name}}</Name>
<Surname>{{Surname}}</Surname>
</Person>
</Loop>
</Meeting>
Will need to end up as
<Meeting>
{{#each People}}
<Person>
<Name>{{Name}}</Name>
<Surname>{{Surname}}</Surname>
</Person>
{{/each}}
</Meeting>
And like wise for Condition tags being converted to the handlebars if statement.
I've attempted to use .Net's XDocument library but I'm struggling to figure out how to actually accomplish this (the IXmlLineInfo instance doesn't provide me with enough info).
It seems as if I may need a way to parse the raw string to get the start and end positions of both the opening tags and closing tags in order to do a straight up text replacement. But I'm not sure how to go about doing this in a manner that can handle the numerous edge cases that comes with editable text.

I was able to accomplish this without needing to use raw string manipulation or the use of IXmlLineInfo.
When encountering a Loop element I simply:
//1. add the opening handlerbars code to the parent elemnet before the Loop element
loopNode.AddBeforeSelf("{{#each " + collection.Value + "}}");
//2. add all the loop element's children to the parent element just after the handlebars code
loopNode.AddBeforeSelf(loopNode.Elements());
//3. Add the closing handlebars statement to the parent after the Loop element
loopNode.AddAfterSelf("{{/each}}");
//4. Then finally remove the Loop element from the DOM
loopNode.Remove();
And I'm left with exactly what I need to send into the handlebars renderer.

What is the difference XElement Nodes() vs Elements()?

Documentation says:
XContainer.Nodes Method ()
Returns a collection of the child nodes of this element or document, in document order.
Remarks
Note that the content does not include attributes. In LINQ to XML, attributes are not considered to be nodes of the tree. They are name/value pairs associated with an element.
XContainer.Elements Method ()
Returns a collection of the child elements of this element or document, in document order.
So it looks like Nodes() has a limitation, but then why does it exist? Are there any possible reasons or advantages of using Nodes()?

The reason is simple: XNode is a base (abstract) class for all xml "parts", and XElement is just one such part (so XElement is subclass of XNode). Consider this code:
XDocument doc = XDocument.Parse("<root><el1 />some text<!-- comment --></root>");
foreach (var node in doc.Root.Nodes()) {
Console.WriteLine(node);
}
foreach (var element in doc.Root.Elements()) {
Console.WriteLine(element);
}
Second loop (over Elements()) will only return one item: <el />
First loop however will return also text node (some text) and comment node (<!-- comment -->), so you see the difference.
You can see what other descendants of XNode there are in documentaiton of XNode class.

It's not the case that Nodes "have a limitation". Nodes are the fundamental building block on which most other things (including Elements) are built.
The XML document is represented as a hierarchy (tree), and the nodes are used to represent the fundamental structure of the hierarchy.
If we consider the following XML document:
<root>
<element>
<child>
Text
</child>
</element>
<!-- comment -->
<element>
<child>
Text
<child>
</element>
</root>
Clearly the whole document cannot be represented as elements, since the comment and the text within the "child" elements are not elements. Instead, it's represented as a hierarchy of nodes.
In this document, there are 5 elements (the root element, two "element" elements and two "child" elements). All of these are nodes, but there are also 3 other nodes: the text within "child" elements, and the comment.
It's misleading to say that nodes have a "limitation" because they don't have attributes. Only elements have attributes, and elements are nodes! But there are other nodes (e.g. the comment) that can't have attributes. So not all types of node have attributes.
In coding terms, Node is the base class on which higher-level types such as Element are built. If you want to enumerate the elements in the document, then using XContainer.Elements() is a nice shortcut to do that - but you could also use XContainer.Nodes() and get all the nodes, including both the elements and the other stuff. (You can check the type of the node to see whether you have an element node, a text node, or whatever; if it's an element, you can up-cast it).

How to read xml string ignoring header?

I want to read a xml string ignoring the header and the comments.
To ignore the comments it's simples and I found a solution here.
But I'm not finding any solution to ignore the header.
Let me give an example:
Consider this xml:
<?xml version="1.0" encoding="iso-8859-1"?>
<!-- Some comments -->
<Tag Attribute="3">
...
</Tag>
I want to read the xml to a string obtaining just the element "Tag" and others elements but withou the "xml version" and the comments.
The element "Tag" is only an example. Could exist many others.
So, I want only this:
<Tag Attribute="3">
...
</Tag>
The code that I've come so far:
XmlReaderSettings settings = new XmlReaderSettings();
settings.IgnoreComments = true;
XmlReader reader = XmlReader.Create("...", settings);
xmlDoc.Load(reader);
And I'm not finding anything on XmlReaderSettings to do that.
Do I need to go node by node choosing only the ones I want? This setting does not exist?
EDIT 1:
Just to resume my problem. I need the contents of the xml to use in a CDATA of a WebService. When I'm sending comments or xml version, I'm getting an specific error of that part of xml. So I assume that when I read the xml without the version, header and comments I'll be good to go.

Here's a really simple solution.
using (var reader = XmlReader.Create(/*reader, stream, etc.*/)
{
reader.MoveToContent();
string content = reader.ReadOuterXml();
}

Well, it seems that there is no settings to ignore declaration, so I had to ignore it myself.
Here's the code I've written for those who might be interested:
private string _GetXmlWithoutHeadersAndComments(XmlDocument doc)
{
string xml = null;
// Loop through the child nodes and consider all but comments and declaration
if (doc.HasChildNodes)
{
StringBuilder builder = new StringBuilder();
foreach (XmlNode node in doc.ChildNodes)
if (node.NodeType != XmlNodeType.XmlDeclaration && node.NodeType != XmlNodeType.Comment)
builder.Append(node.OuterXml);
xml = builder.ToString();
}
return xml;
}

If you want to only get the Tag elements, you should just read the XML as normal, then find them using the XmlDocument's XPath capabilities.
For your xmlDoc object:
var nodes = xmlDoc.DocumentElement.SelectNodes("Tag");
You can then iterate through these like so:
foreach (XmlNode node in nodes) { }
Or, obviously, you could just put your SelectNodes query into the foreach loop, if you're never going to reuse the nodes object.
This will return all Tag elements within your XML document, and you can do whatever you see fit with them.
There's no need to ever encounter comments while using XmlDocument if you don't want to, and you're not going to end up getting results including either the header or the comments. Is there a particular reason you're trying to remove pieces of the XML before you begin parsing it?
Edit: Based on your edit, it seems like you're having a problem with the header giving an error when you try to pass it. You probably shouldn't straight-up remove the header, so your best option might be to change the header to one that you know works. You can change the header (declaration) like so:
XmlDeclaration xmlDeclaration;
xmlDeclaration = yourDocument.CreateXmlDeclaration(
yourVersion,
yourEncoding,
isStandalone);
yourDocument.ReplaceChild(xmlDeclaration, doc.FirstChild);

CDATA xml parsing

I am getting response in xml format and data are inside cData section in xml nodes. now when i am trying to extract node value then getting value with cdata text.
how can i parse it?
xml:
<myrecords>
<record>
<id><![CDATA[8683]]></id>
<tempid><![CDATA[4567]]></id>
<type><![CDATA[db]]></type>
<params>
<![CDATA[<db> <dbid>254</dbid> <isdb>true</isdb> <mydb>sample</mydb> </db>]]>
</params>
</record>
</myrecords>
i used code to get entire list but i need to get only particular node
foreach (var child in xdoc.Root.Elements())
{
Console.WriteLine("{0}{1}",child.Name,child.Value);
}
the above code list all the cdata value..
i need to get only dbid,isdb,mydb values from the above xml

For the "outer" Xml document, the value is nothing but character data. You'll have to parse that value separately if you want to treat it as Xml.

Decode CDATA section in C#

I have a bit of XML as follows:
<section>
<description>
<![CDATA[
This is a "description"
that I have formatted
]]>
</description>
</section>
I'm accessing it using curXmlNode.SelectSingleNode("description").InnerText but the value returns \r\n This is a "description"\r\n that I have formatted instead of This is a "description" that I have formatted.
Is there a simple way to get that sort of output from a CDATA section? Leaving the actual CDATA tag out seems to have it return the same way.

You can use Linq to read CDATA.
XDocument xdoc = XDocument.Load("YourXml.xml");
xDoc.DescendantNodes().OfType<XCData>().Count();
It's very easy to get the Value this way.
Here's a good overview on MSDN: http://msdn.microsoft.com/en-us/library/bb308960.aspx
for .NET 2.0, you probably just have to pass it through Regex:
string xml = #"<section>
<description>
<![CDATA[
This is a ""description""
that I have formatted
]]>
</description>
</section>";
XPathDocument xDoc = new XPathDocument(new StringReader(xml.Trim()));
XPathNavigator nav = xDoc.CreateNavigator();
XPathNavigator descriptionNode =
nav.SelectSingleNode("/section/description");
string desiredValue =
Regex.Replace(descriptionNode.Value
.Replace(Environment.NewLine, String.Empty)
.Trim(),
#"\s+", " ");
that trims your node value, replaces newlines with empty, and replaces 1+ whitespaces with one space. I don't think there's any other way to do it, considering the CDATA is returning significant whitespace.

I think the best way is...
XmlCDataSection cDataNode = (XmlCDataSection)(doc.SelectSingleNode("section/description").ChildNodes[0]);
string finalData = cDataNode.Data;

Actually i think is pretty much simple. the CDATA section it will be loaded in the XmlDocument like another XmlNode the difference is that this node is going to has the property NodeType = CDATA, wich it mean if you have the XmlNode node = doc.SelectSingleNode("section/description"); that node will have a ChildNode with the InnerText property filled the pure data, and there is you want to remove the especial characters just use Trim() and you will have the data.
The code will look like
XmlNode cDataNode = doc.SelectSingleNode("section/description").ChildNodes[0];
string finalData = cDataNode.InnerText.Trim();
Thanks
XOnDaRocks

A simpler form of #Franky's solution:
doc.SelectSingleNode("section/description").FirstChild.Value
The Value property is equivalent to the Data property of the casted XmlCDataSection type.

CDATA blocks are effectively verbatim. Any whitespace inside CDATA is significant, by definition, according to XML spec. Therefore, you get that whitespace when you retrieve the node value. If you want to strip it using your own rules (since XML spec doesn't specify any standard way of stripping whitespace in CDATA), you have to do it yourself, using String.Replace, Regex.Replace etc as needed.