Linq to XML elements - c#

Hi I try to read an xml file with LINQ.
The name of the file is:categorizedBooks.xml
and the content of the file looks like this:
<category name=".NET">
<books>
<book>CLR via C#</book>
<book>Essential .NET</book>
</books>
</category>
The code for reading the file looks like this:
XElement rootss = XElement.Load(#"D:/categorizedBooks.xml");
XElement dotNetCategoryss = rootss.Element("category");
XAttribute namehallo = dotNetCategoryss.Attribute("name");
XElement booksss = dotNetCategoryss.Element("books");
IEnumerable<XElement> bookElements = booksss.Elements("book");
Console.WriteLine((string)dotNetCategoryss);
foreach (XElement bookElement in bookElements)
{
Console.WriteLine(" - " + (string)bookElement);
}
But i get null on this line:
XAttribute namehallo = dotNetCategoryss.Attribute("name");
So how to fix this , so that it not will be null?
Thank you

Your doc root is the category element - try:
XAttribute namehallo = rootss.Attribute("name");
Console.WriteLine(namehallo.Value);
You'll have to change your other XElement references similarly

instead of XElement.Load use XDocument.Load or XDocument.Parse
var xml = #"
<category name='.NET'>
<books>
<book>CLR via C#</book>
<book>Essential .NET</book>
</books>
</category>";
var document = XDocument.Parse(xml);
// returns: .NET
var category = document
.Element("category")
.Attributes("name")
.Select(p => p.Value);
// returns: CLR via C#, Essential .NET
var books = document
.Descendants("book")
.Select(p => p.Value);

Related

C# split xml innertext or parse innerxml

I have an XML file with a structure similar to this
<entry name="something">
<members>
<member>aaa</member>
<member>bbb</member>
</members>
</entry>
<entry name="something_else">
<members>
<member>ccc</member>
<member>ddd</member>
</members>
</entry>
I need to be able to get the values out of each of the member nodes to store in a datatable. if i use the innertext property, it concatenates the values (aaabbb). there is nothing discernible to split the string on. I can also use the inner XML but then i just get a string with the XML structure (aaa bbb<\member>)
What is the best way to get each value out of the XML elements and store it in a string array?
here is what I have been trying.
foreach (XmlNode grpNode in GrpList)
{
subNode = grpNode.Attributes["name"];
if (subNode != null)
{
Obj = grpNode.Attributes["name"].Value;
}
subNode = grpNode["members"];
if (subNode != null)
{
string innerXml = string.Empty;
innerXml = grpNode["members"].InnerXml.ToString();
string[] tempArrary = innerXml.Split(new char[] {'>', '<'});
}
}
You can use Xpath to iterate through Entry nodes and get the members within it like this
string xml = "<root><entry name='something'>" +
"<members>" +
"<member>aaa</member>" +
"<member>bbb</member>" +
"</members>" +
"</entry>" +
"<entry name='something_else'>" +
"<members>" +
"<member>ccc</member>" +
"<member>ddd</member>" +
"</members>" +
"</entry></root>";
XmlDocument doc = new XmlDocument();
doc.LoadXml(xml);
var memsList = doc.SelectNodes("//entry");
foreach (XmlNode a in memsList)
{
Console.WriteLine(a.Attributes["name"].Value);
var memList = a.SelectNodes("members/member");
foreach(XmlNode x in memList)
Console.WriteLine(x.InnerText);
}
You need to iterate the child elements within members, so something like:
foreach (var node in grpNode["members"].ChildNodes)
{
var value = node.InnerText;
}
That said, you would be better off using LINQ to XML unless you have some specific reason to use XmlDocument. This gives you much more expressive code, for example:
var doc = XDocument.Parse(xml);
var something = doc.Descendants("entry")
.Where(e => (string)e.Attribute("name") == "something")
.Single();
var somethingMembers = something.Descendants("member")
.Select(e => e.Value)
.ToArray();
This should do the trick:
XDocument xdoc = XDocument.Load(#"Path/to/file");
var result = xdoc.Descendants("member").Select (x => x.Value).ToArray();
Result:
Demo Code
the xml you've provided isn't valid. But assuming you just want the inner text of all member nodes into a string array, I'd just use Linq-To-Xml (XDocument):
var results = XDocument.Parse(xmlString)
.Descendants("member")
.Select(m => m.Value)
.ToArray();
Even though you're using the old XmlDocument API, by throwing in an .OfType<XmlNode>() you can convert an XmlNodeList to a generic enumerable and thereby mix in some linq and lambda syntax, for instance:
var tempArrary = subNode.SelectNodes("member").OfType<XmlNode>().Select(n => n.InnerText).ToArray();

XDocument does not load Xml string properly

I'm trying to do the following: load an Xml string into a XDocument object, but when I try to access elements through Descendants method it return nothing when I tried to see the value of inner elements in Visual Studio it does not recognize it as Xml so what is the problem here?
string xml = #"<ArrayOfKeyValueOfstringint xmlns=""http://schemas.microsoft.com/2003/10/Serialization/Arrays"" xmlns:i=""http://www.w3.org/2001/XMLSchema-instance"">
<KeyValueOfstringint>
<Key>crscmprsn_ttlprt1</Key>
<Value>1</Value>
</KeyValueOfstringint>
<KeyValueOfstringint>
<Key>ptntmntrfrm_ttlprt1</Key>
<Value>1</Value>
</KeyValueOfstringint>
</ArrayOfKeyValueOfstringint>";
var xdoc = XDocument.Parse(xml);
IEnumerable<XElement> elements = xdoc.Descendants("KeyValueOfstringint");
var lst = new List<KeyValuePair<string,int>>();
foreach (var item in elements)
{
var k = item.Element("Key").Value;
int v = int.Parse(item.Element("Value").Value);
var kvp = new KeyValuePair<string,int>(k,v);
lst.Add(kvp);
}
You need to specify namespace to get your elements:
var ns = "http://schemas.microsoft.com/2003/10/Serialization/Arrays";
var elements = xdoc.Descendants(ns + "KeyValueOfstringint");
For more information about xml namespaces take a look at: Working with XML Namespaces

Adding an element to this xml structure

<root>
<element1>innertext</element1>
<element2>innertext</element2>
<element3>
<child1>innertext</child1>
</element3>
</root>
I have an xml structure shown above.
I would like to "append" the xml file (it is already created) to add another "child" inside element3>, so that it will look like this:
<root>
<element1>innertext</element1>
<element2>innertext</element2>
<element3>
<child1>innertext</child1>
<child2>innertext</child2>
</element3>
</root>
Linq to xml and/or Xpath would be great
EDIT:
I have tried doing this:
XElement doc = XElement.Load(mainDirectory);
XElement newElem = doc.Elements("element3").First();
newElem.Add(new XElement("child2", "child2innertext"));
doc.Add(newElem);
doc.Save(mainDirectory);
XmlDocument xDoc = new XmlDocument();
xDoc.Load("filename.xml");
foreach (XmlNode xNode in xDoc.SelectNodes("/root/element3"))
{
XmlElement newElement = xDoc.CreateElement("Child2");
xNode.AppendChild(newElement);
xNode.InnerText = "myInnerText";
}
With XDocument you can achieve this as:
string xml = "<root><element1>innertext</element1><element2>innertext</element2><element3><child1>innertext</child1></element3></root>";
var doc = XDocument.Parse(xml); //use XDocument.Load("filepath"); in case if your xml is in a file.
var el3 = doc.Descendants("element3").FirstOrDefault();
el3.Add(new XElement("child2", "innertext"));
Please, try this LINQPAD example
void Main()
{
var xml =
#"<root>
<element1>innertext</element1>
<element2>innertext</element2>
<element3>
<child1>innertext</child1>
</element3>
</root>";
var doc = XDocument.Parse(xml);
doc.Root.Element("element3")
.Add(new XElement("child2", "innertext"));
doc.Dump();
}

Simple Xml parse with Xdocument

I want parse xml in windows store app with Xdocument.
I tried this,but returned with null:
XDocument xDoc;
string title= "";
xDoc = XDocument.Load(url);
var elements = from x in xDoc.Descendants()
select new
{
title = x.Descendants("title").First().Value,
};
foreach (var el in elements)
_title = title;
Xml contents:
<title type='text'>tiitle</title>
<content type='text'> gfgdgdggd</content>
<link rel='related' type='application/atom+xml' href='http....'/>
How can is retrive text from attributes ?
As ZevSpitz already mentioned, your XML is invalid. I modified it a bit to be able to test my code:
<root>
<title type="text">title</title>
<content type="text">gfgdgdggd</content>
</root>
You can retrieve values from the type attributes with the following code:
XDocument xDoc = XDocument.Parse(xml);
var types =
from x in xDoc.Root.Descendants()
select x.Attribute("type").Value;
In my case xml is declared as follows:
private string xml =
#"<root>
<title type=""text"">title</title>
<content type=""text"">gfgdgdggd</content>
</root>";
You can still use your code to load the XML from a URL if the file contents are the same.
Try:
var types =
from e in xDoc.Descendants()
select (string)e.Attribute("type");
foreach (string type in types) {
Console.WriteLine(type);
}

Filter XDocument more efficiently

I would like to filter with high performance XML elements from an XML document.
Take for instance this XML file with contacts:
<?xml version="1.0" encoding="ISO-8859-1"?>
<?xml-stylesheet type="text/xsl" href="asistentes.xslt"?>
<contactlist evento="Cena Navidad 2010" empresa="company">
<contact type="1" id="1">
<name>Name1</name>
<email>xxxx#zzzz.es</email>
<confirmado>SI</confirmado>
</contact>
<contact type="1" id="2">
<name>Name2</name>
<email>xxxxxxxxx#zzzze.es</email>
<confirmado>Sin confirmar</confirmado>
</contact>
</contaclist>
My current code to filter from this XML document:
using System;
using System.Xml.Linq;
class Test
{
static void Main()
{
string xml = #" the xml above";
XDocument doc = XDocument.Parse(xml);
foreach (XElement element in doc.Descendants("contact")) {
Console.WriteLine(element);
var id = element.Attribute("id").Value;
var valor = element.Descendants("confirmado").ToList()[0].Value;
var email = element.Descendants("email").ToList()[0].Value;
var name = element.Descendants("name").ToList()[0].Value;
if (valor.ToString() == "SI") { }
}
}
}
What would be the best way to optimize this code to filter on <confirmado> element content?
var doc = XDocument.Parse(xml);
var query = from contact in doc.Root.Elements("contact")
let confirmado = (string)contact.Element("confirmado")
where confirmado == "SI"
select new
{
Id = (int)contact.Attribute("id"),
Name = (string)contact.Element("name"),
Email = (string)contact.Element("email"),
Valor = confirmado
};
foreach (var contact in query)
{
...
}
Points of interest:
doc.Root.Elements("contact") selects only the <contact> elements in the document root, instead of searching the whole document for <contact> elements.
The XElement.Element method returns the first child element with the given name. No need to convert the child elements to a list and take the first element.
The XElement and XAttribute classes provide a wide selection of convenient conversion operators.
You could use LINQ:
foreach (XElement element in doc.Descendants("contact").Where(c => c.Element("confirmado").Value == "SI"))

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