Develop Reference

Adding node to existing xml element

I'm getting this error when trying to append a node to existing element in my xml document.The error is: Object reference not set to an instance of an object.
<houses>
<house windowsc="three">
<wind>0</wind>
<windows>
</windows>
</house>
</houses>
Code:
XmlDocument xDoc = new XmlDocument();
xDoc.Load("C:\\Houseplans.xml");
XmlElement xhousing = xDoc.DocumentElement["houses/house[#windowsc=\"three\"]/windows"];
XmlNode xName = xDoc.CreateElement("Name");
xName.InnerText = "hi";
xhousing.AppendChild(xName);

You want to use SelectSingleNode:
XmlNode xhousing = xDoc.SelectSingleNode(#"//house[#windowsc='three']/windows");
XmlNode xName = xDoc.CreateElement("Name");
xName.InnerText = "hi";
xhousing.AppendChild(xName);

parsing attribute from xml file

I'm trying to parse the following:
<?xml version="1.0" encoding="utf-8"?>
<GC>
<CREATED>01/23/2014 16:10:18</CREATED>
<DATA>
<CONTAINER name="home" type="xml" version="1.1.0.0">
<HEADER>
<ATTRIBUTE name="lang" value="EN" />
<ATTRIBUTE name="destination" value="UK" />
</HEADER>
</CONTAINER>
</DATA>
</GC>
How do I go about finding the value when name="lang"?
So far I have this:
XmlDocument Doc = new XmlDocument();
Doc.Load(#path);
XmlNode node = Doc.DocumentElement.SelectSingleNode("/GC/DATA/CONTAINER/HEADER/ATTRIBUTE/NAME");
string SI = node.Attributes["lang"].InnerText;
Doesn't seem to work unfortunately, could use some help. Many thanks.

This will do it:
XmlNode node =
Doc.SelectSingleNode("/GC/DATA/CONTAINER/HEADER/ATTRIBUTE[#name = 'lang']/#value");
string SI = node.InnerText;
And I would advise using a null check:
XmlNode node =
Doc.SelectSingleNode("/GC/DATA/CONTAINER/HEADER/ATTRIBUTE[#name = 'lang']/#value");
string SI = null;
if(node != null)
{
SI = node.InnerText;
}

With using LINQ to XML you can get it like this:
XDocument xDoc = XDocument.Load("path");
var element = xDoc.Descendans("ATTRIBUTE").First();
var nameAttribute = (string)element.Attribute("name");

This will get you the value of the attribute in the ATTRIBUTE tag which has name == lang:
XmlDocument Doc = new XmlDocument();
Doc.Load(#path);
XmlNode node = Doc.DocumentElement.SelectSingleNode("/GC/DATA/CONTAINER/HEADER/ATTRIBUTE[#name='lang']");
string SI = node.Attributes["value"].InnerText;

XmlNode node = Doc.DocumentElement.SelectSingleNode("/GC/DATA/CONTAINER/HEADER/ATTRIBUTE[#name='lang']");
string SI = node.Attributes["value"].Value;

Get data by XPath in C#

So I have this XML:
<?xml version="1.0" encoding="utf-8"?>
<M_ChucVu>
<ChucVu>
<MaChucVu>1
</MaChucVu>
<TenChucVu>
</TenChucVu>
</ChucVu>
<ChucVu>
<MaChucVu>2
</MaChucVu>
<TenChucVu>
</TenChucVu>
</ChucVu>
<ChucVu>
<MaChucVu>23</MaChucVu>
<TenChucVu>12</TenChucVu>
</ChucVu>
<ChucVu>
<MaChucVu>44</MaChucVu>
<TenChucVu>44</TenChucVu>
</ChucVu>
</M_ChucVu>
and I want to retrieve the ChucVu tags that contain an empty TenChucVu tag so the result is this:
<ChucVu>
<MaChucVu>1
</MaChucVu>
<TenChucVu>
</TenChucVu>
</ChucVu>
<ChucVu>
<MaChucVu>2
</MaChucVu>
<TenChucVu>
</TenChucVu>
</ChucVu>

XDocument doc = ...;
var query = doc.XPathSelectElements("//ChucVu[TenChucVu='']");

Another XPath that should work
/M_ChucVu[./ChucVu/TenChucVu='']
for example
var doc = new XmlDocument();
doc.LoadXml(yourXmlString);
var elem = doc.DocumentElement;
var sel = elem.SelectNodes("/M_ChucVu[./ChucVu/TenChucVu!='']");
// print or use sel.InnerXml

The XPath you need is:
/*/ChucVu[not(string(TenChucVu))]
or
/*/ChucVu[string-length(TenChucVu)=0]

You can as:
string xparth = String.Format("//ChucVu[TenChucVu='{0}']", '');
XmlDocument doc = new XmlDocument();
doc.Load("Xml");
XmlElement root = doc.DocumentElement;
XmlNode node = root.SelectSingleNode(xparth);
XmlNodeList list = root.SelectNodes(xparth);

I need to convert an XML string into an XmlElement

I'm looking for the simplest way to convert a string containing valid XML into an XmlElement object in C#.
How can you turn this into an XmlElement?
<item><name>wrench</name></item>

Use this:
private static XmlElement GetElement(string xml)
{
XmlDocument doc = new XmlDocument();
doc.LoadXml(xml);
return doc.DocumentElement;
}
Beware!!
If you need to add this element to another document first you need to Import it using ImportNode.

Suppose you already had a XmlDocument with children nodes, And you need add more child element from string.
XmlDocument xmlDoc = new XmlDocument();
// Add some child nodes manipulation in earlier
// ..
// Add more child nodes to existing XmlDocument from xml string
string strXml =
#"<item><name>wrench</name></item>
<item><name>screwdriver</name></item>";
XmlDocumentFragment xmlDocFragment = xmlDoc.CreateDocumentFragment();
xmlDocFragment.InnerXml = strXml;
xmlDoc.SelectSingleNode("root").AppendChild(xmlDocFragment);
The Result:
<root>
<item><name>this is earlier manipulation</name>
<item><name>wrench</name></item>
<item><name>screwdriver</name>
</root>

Use XmlDocument.LoadXml:
XmlDocument doc = new XmlDocument();
doc.LoadXml("<item><name>wrench</name></item>");
XmlElement root = doc.DocumentElement;
(Or in case you're talking about XElement, use XDocument.Parse:)
XDocument doc = XDocument.Parse("<item><name>wrench</name></item>");
XElement root = doc.Root;

You can use XmlDocument.LoadXml() to do this.
Here is a simple examle:
XmlDocument xmlDoc = new XmlDocument();
xmlDoc.LoadXml("YOUR XML STRING");

I tried with this snippet, Got the solution.
// Sample string in the XML format
String s = "<Result> No Records found !<Result/>";
// Create the instance of XmlDocument
XmlDocument doc = new XmlDocument();
// Loads the XML from the string
doc.LoadXml(s);
// Returns the XMLElement of the loaded XML String
XmlElement xe = doc.DocumentElement;
// Print the xe
Console.out.println("Result :" + xe);
If any other better/ efficient way to implement the same, please let us know.
Thanks & Cheers

Change XML root element name

I have XML stored in string variable:
<ItemMasterList><ItemMaster><fpartno>xxx</fpartno><frev>000</frev><fac>Default</fac></ItemMaster></ItemMasterList>
Here I want to change XML tag <ItemMasterList> to <Masterlist>. How can I do this?

System.Xml.XmlDocument and the associated classes in that same namespace will prove invaluable to you here.
XmlDocument doc = new XmlDocument();
doc.LoadXml(yourString);
XmlDocument docNew = new XmlDocument();
XmlElement newRoot = docNew.CreateElement("MasterList");
docNew.AppendChild(newRoot);
newRoot.InnerXml = doc.DocumentElement.InnerXml;
String xml = docNew.OuterXml;

I know i am a bit late, but just have to add this answer as no one seems to know about this.
XDocument doc = XDocument.Parse("<ItemMasterList><ItemMaster><fpartno>xxx</fpartno><frev>000</frev><fac>Default</fac></ItemMaster></ItemMasterList>");
doc.Root.Name = "MasterList";
Which returns the following:
<MasterList>
<ItemMaster>
<fpartno>xxx</fpartno>
<frev>000</frev>
<fac>Default</fac>
</ItemMaster>
</MasterList>

You can use LINQ to XML to parse the XML string, create a new root and add the child elements and attributes of the original root to the new root:
XDocument doc = XDocument.Parse("<ItemMasterList>...</ItemMasterList>");
XDocument result = new XDocument(
new XElement("Masterlist", doc.Root.Attributes(), doc.Root.Nodes()));

Using the XmlDocument way, you can do this as follows (and keep the tree intact):
XmlDocument oldDoc = new XmlDocument();
oldDoc.LoadXml("<ItemMasterList><ItemMaster><fpartno>xxx</fpartno><frev>000</frev><fac>Default</fac></ItemMaster></ItemMasterList>");
XmlNode node = oldDoc.SelectSingleNode("ItemMasterList");
XmlDocument newDoc = new XmlDocument();
XmlElement ele = newDoc.CreateElement("MasterList");
ele.InnerXml = node.InnerXml;
If you now use ele.OuterXml is will return: (you you just need the string, otherwise use XmlDocument.AppendChild(ele) and you will be able to use the XmlDocument object some more)
<MasterList>
<ItemMaster>
<fpartno>xxx</fpartno>
<frev>000</frev>
<fac>Default</fac>
</ItemMaster>
</MasterList>

As pointed by Will A, we can do it that way but for case where InnerXml equals the OuterXml the following solution will work out:
// Create a new Xml doc object with root node as "NewRootNode" and
// copy the inner content from old doc object using the LastChild.
XmlDocument docNew = new XmlDocument();
XmlElement newRoot = docNew.CreateElement("NewRootNode");
docNew.AppendChild(newRoot);
// The below line solves the InnerXml equals the OuterXml Problem
newRoot.InnerXml = oldDoc.LastChild.InnerXml;
string xmlText = docNew.OuterXml;