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Concatenate XML fields in one single record

I am new to working with XML in C#. I have a requirement to concatenate multiple fields in one single record.
For example I have an XML with multiple Records:
Input
<Students>---------------------->1st Record
<Validate>True</Validate>
<StudentName>Joe</StudentName>
<ID>1</ID>
<BookName>C#</BookName>
</Students>
<Students>----------------------->2nd Record
<StudentName>Van</StudentName>
<ID>2</ID>
<BookName>Java</BookName>
</Students>
The field <validate> will occur only once and the expected Output is that the 2nd Record under students i.e StudentName, ID, BookName should come under the 1st Record <Students> tag
OutPut
<Students>------------------->Both record should be added to one Record
<Validate>True</Validate>
<StudentName>Joe</StudentName>
<ID>1</ID>
<BookName>C#</BookName>
<StudentName>Van</StudentName>
<ID>2</ID>
<BookName>Java</BookName>
</Students>

The easiest way is to use LINQ to XML. You parse the XML, get all the child elements in each Students element and put them into a a single new Students element:
var doc = XDocument.Parse(xml);
var children = doc.Descendants("Students")
.Elements();
var newStudents = new XElement("Students", children);
See this fiddle for a working example.

combine two xml_docs C# xmlDocument

I have been using the following SO, How to merge two XmlDocuments in C#, to try and merge two sample xml files into one. Essentially here are my two xml files
test1.xml:
<root>
<Name>
<id>4</id>
<First_name>Tony</First_name>
<last_name>""</last_name>
</Name>
<Name>
<id>6</id>
<First_name>Donny</First_name>
<last_name>Test</last_name>
<middle_name>Ward</middle_name>
</Name>
</root>
And test2.xml
<root>
<Name>
<id>1</id>
<First_name>Nick</First_name>
<last_name>Tester</last_name>
</Name>
<Name>
<id>2</id>
<First_name>Lauren</First_name>
<last_name>MsTester</last_name>
</Name>
</root>
I am using this code snippet it to merge the into the one file but the procedure is not actually combining them. I am a little knew to xmlDocument class and still trying to navigate this issue correctly.
Code:
XmlDocument xmlreader1 = new XmlDocument();
xmlreader1.Load("C:\\Temp\\test1.xml");
XmlDocument xmlreader2 = new XmlDocument();
xmlreader2.Load("C:\\Temp\\test2.xml");
foreach (XmlNode node in xmlreader2.DocumentElement.ChildNodes)
{
XmlNode importedDocument = xmlreader1.ImportNode(node, true);
xmlreader1.DocumentElement.AppendChild(importedDocument);
}
I believe this is correct to take each child node of root (in this case <name>) from test2.xml and append it to test1.xml. I have also tried as:
XmlNode importedDocument = xmlreader1.ImportNode(xmlreader2.DocumentElement, true);
xmlreader1.DocumentElement.AppendChild(importedDocument);
to no avail again any suggestions would be greatly appreciated.

It's not entirely clear what merge operations you need to perform - but if you just need to copy the root node's child elements, that's really simple with LINQ to XML:
XDocument doc1 = XDocument.Load("test1.xml");
XDocument doc2 = XDocument.Load("test2.xml");
doc1.Root.Add(doc2.Root.Elements());
doc1.Save("test3.xml");
This will not perform any actual merging though - if you have elements with the same ID in both files, you'll end up with both elements in the result, rather than one merged element.
Personally I always prefer using LINQ to XML over the old XmlDocument API - I would strongly recommend using it when you have the opportunity to do so.

XPath last() does not work properly

I have following xml
<root>
<data>
<person>tewst</person>
<data>
<phone>djk</phone>
<email>dsd</email>
</data>
</data>
</root>
Using c# SelectSingleNode I am trying to get to second "data" node and insert the new element call "phone2" after email tag.
Issue is I can not get to the correct "data" node. This is the code I am using to get there and it does not work. Any help would be appreciated. Thank you
XMLDocument doc = new XMLDocument("xml file here");
var node = doc.SelectSingleNode("//data[last()]");
XMLElement phone1 = doc.CreateElement("phone2");
phone1.InnerText = "12";
node.AppendChild(phone1);
Problem is that node is null.
Solution:
XMLDocument doc = new XMLDocument("xml file here");
var node = doc.SelectSingleNode("(//data)[last()]");

//data[last()] selects data nodes that are their parent's last data child, so it selects 2 nodes in your example:
1) last data child of the root node
<data>
<person>tewst</person>
<data>
<phone>djk</phone>
<email>dsd</email>
</data>
</data>
2) and last data child of the first data node
<data>
<phone>djk</phone>
<email>dsd</email>
</data>
To select the last data in the whole document, use:
(//data)[last()]
//data will generate the node-set for all descendant data elements, nested or not,
[last()] will select the last node of the node-set
with the brackets () around //data, it ensures it's interpreted as //data then [last()], instead of // then data[last()]

There are a couple different ways you can do this.
(1) If you know that the structure of the XML will always be like the above - "root" element, exactly one "data" child, and exactly one "data" child beneath the "data" parent, you can access the second "data" element directly using the XPath expression:
XmlNode node = doc.SelectSingleNode("/root/data/data");
(2) If there are multiple "data" elements beneath the "root" element, then you can do the following:
XmlNodeList nodeList = doc.SelectNodes("//data/data");
This XPath expresion will return the first "data" element beneath every top level "data" element in the document. So for instance, if you had an XML document like this:
<root>
<data>
<person>tewst</person>
<data>
<phone>djk</phone>
<email>dsd</email>
</data>
</data>
<data>
<person>two</person>
<data>
<phone>bbb</phone>
<email>ddd</email>
</data>
</data>
</root>
... the output of this code snipped:
XmlNodeList nodeList = doc.SelectNodes("//data/data");
foreach (XmlNode parentData in nodeList)
Console.WriteLine(parentData.InnerXml.ToString());
... will produce:
<phone>djk</phone><email>dsd</email>
<phone>bbb</phone><email>ddd</email>
Hope this helps.

c# xmlnode select single node to remove

I have an XML document that has nodes/values like this:
<data name="btnAutoTrans" xml:space="preserve">
<value>Auto Trans</value>
</data>
<data name="btnDieEngine" xml:space="preserve">
<value>Diesel Engine</value>
</data>
I need to select a single node for a specific name="btnDieEngine" (for example)
but all the code I have tried from searching google always returns NULL value.
The original code I had was
XmlNode node = xmldoc.SelectSingleNode("data[name='btnDieEngine']");
but this returns null.
Any help would be appreciated

Your XPath is invalid. Try that one:
XmlNode node = xmldoc.SelectSingleNode("data[#name='btnDieEngine']");

How to remove an element from XML file using Linq to XML and lambda expression

I have an xml as below
<Person>
<Name>xxx</Name>
<Age>xx</Age>
<Data>xxxx</Data>
</Person>
<Person>
<Name>xxx</Name>
<Age>xx</Age>
<Data>xxxx</Data>
</Person>
<Person>
<Name>xxx</Name>
<Age>xx</Age>
<Data>xxxx</Data>
</Person>
How to remove <Data> element from the tree using Linq to XML, Lamda Expression in C#? where <Data> is a auto generated element and XML structure may vary.

it all depends on what element you want to remove but you can use something like this
XDocument people = XDocument.Load("filenamre.xml");
IEnumerable<XElement> Person = people.Element("Person");
//gets the element you want to remove based on value
XElement name = Person.Where(p => p.Element("xxx").Value == "1").FirstOrDefault();
//removes the name
name.Remove();
//create a new file without the element
people.Save(Server.MapPath("Newfilenamre.xml"));

Removing element other than first one. Means only first must be there rest all must be deleted.