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How to select xmlnode from its key using XPATH

Here is my XML file
<Drive>
<Data0 Key="1" Name="AA" />
<Data1 Key="2" Name="BB" />
<Data2 Key="4" Name="CC" />
<Data3 Key="10" Name="WW" />
<Data4 Key="11" Name="WE" />
<Data5 Key="12" Name="VW" />
</Drive>
I want to select all nodes where their [Key] start with "1" using C# and XML XPATH
I tried this:
XmlNodeList FKNodes = node.SelectNodes("*/* [#Key like '1*']")

You can use * to select element of any name, and use starts-with() function to match the Key attribute value partially :
XmlNodeList FKNodes = node.SelectNodes("//*[starts-with(#Key, '1')]")
xpath demo

Split xml into files - method takes less memory

I need to split my XML into files.
This is structure of my sample XML:
<Data Code="L6POS1">
<Lots RowVersion="464775">
<Lot Id="5" Quantity="10068.0000" GUID="AA616D3D-F442-6AEE-0BAB-1D13F6961C2A" />
<Lot Id="99" Quantity="0.0000" GUID="24A9C957-EC98-85D5-8F96-0120F6E8A572" />
<Lot Id="101" Quantity="0.0000" GUID="124D17A2-1568-DB02-4327-4669FE00F741" />
<Lot Id="103" Quantity="0.0000" GUID="DD1730FF-27CF-1269-7AC2-3152CB6FDC46" />
<Lot Id="105" Quantity="0.0000" GUID="1F25378F-30D4-E4E0-9939-1E9E69C806C1" />
<Lot Id="188" Quantity="0.0000" GUID="2E860029-29B3-54C2-B8D1-0C6ABDA42DFF" />
<Lot Id="189" Quantity="0.0000" GUID="D3C58850-BC23-E8DE-A919-09CCB3F8A1D3" />
</Lots>
Expected result: FirstFile:
<Data Code="L6POS1">
<Lots RowVersion="464775">
<Lot Id="5" Quantity="10068.0000" GUID="AA616D3D-F442-6AEE-0BAB-1D13F6961C2A" />
<Lot Id="99" Quantity="0.0000" GUID="24A9C957-EC98-85D5-8F96-0120F6E8A572" />
<Lot Id="101" Quantity="0.0000" GUID="124D17A2-1568-DB02-4327-4669FE00F741" />
<Lot Id="103" Quantity="0.0000" GUID="DD1730FF-27CF-1269-7AC2-3152CB6FDC46" />
</Lots>
</Data>
And SecondFile:
<Data Code="L6POS1">
<Lots RowVersion="464775">
<Lot Id="105" Quantity="0.0000" GUID="1F25378F-30D4-E4E0-9939-1E9E69C806C1" />
<Lot Id="188" Quantity="0.0000" GUID="2E860029-29B3-54C2-B8D1-0C6ABDA42DFF" />
<Lot Id="189" Quantity="0.0000" GUID="D3C58850-BC23-E8DE-A919-09CCB3F8A1D3" />
</Lots>
</Data>
Actually I'm using:
private IEnumerable<XElement> CreateXMLPackagesByType(string syncEntityName, XElement root)
{
var xmlList = new List<XElement>();
IEnumerable<XElement> childNodes = root.Elements();
var childsCount = childNodes.Count();
var skip = 0;
var take = ConfigurationService.MaxImportPackageSize;
var rootAttributes = root.Attributes();
XElement rootWithoutDescendants;
while (skip < childsCount)
{
rootWithoutDescendants = new XElement(root.Name);
rootWithoutDescendants.Add(rootAttributes);
var elems = childNodes.Skip(skip).Take(take);
skip += take;
xmlList.Add(CreatePackage(rootWithoutDescendants, elems));
}
return xmlList;
}
private XElement CreatePackage(XElement type, IEnumerable<XElement> elems)
{
type.Add(elems);
var root = new XElement("Data", type);
root.Add(new XAttribute("Code", ConfigurationService.Code));
return root;
}
Unfortunately, in this way a get OutOfMemoryException with bigger XML files on older hardware. It is better way to split XElement?

Previous comments suggesting to use a SAX parser are correct -- that way you get each event (element, etc) one at a time, and you don't have to keep anything around afterwards.
If you're absolutely certain that your data is as neatly broken into lines as your example, a quick-and-dirty method would be to not even parse, but just read a line at a time. Handle the first two, then break up the rest how you want, then handle the last two. But be really sure (in other words, check) that every <Lot> element takes up exactly one physical line; as you probably already know, there's no reason they have to be that way in XML in general.

Getting the attribute value from two XML nodes with same data

First off, I'm sorry for the name. I couldn't think of a way to describe my issue in a question form. But this is what I'm trying to do.
Here is what my xml is looking like:
<Settings>
<Display_Settings>
<Screen>
<Name Name="Screen" />
<ScreenTag Tag="Screen Tag" />
<LocalPosition X="12" Y="81" Z="28" />
<Width Width="54" />
<Height Height="912" />
</Screen>
<Camera_Name Name="Camera">
<CameraTag Tag="Camera Tag" />
<LocalPosition X="354" Y="108" Z="Z Local Position" />
<Far Far="98" />
<Near Near="16" />
<FOV FOV="78" />
<AspectRatio AspectRatio="1" />
<ScreenDistance ScreenDistance="2" />
</Camera_Name>
</Display_Settings>
</Settings>
What I want is to access the attribute values stored within my local position node. I got some help with this and I can access the screens local position attribute value with this code:
var xdoc = XDocument.Load("C:\\Test.xml");
int x = int)xdoc.Descendants("LocalPosition").First().Attribute("X");
This happily returns 12 when I debug it. But, I also want to my cameras local position to be out putted as well.
Can someone please show me how to do this?

You can grab Camera and Screen position using Descendants and then accessing it components with Attribute. Code examples are given below:
var cameraPosition = xdoc.Descendants("Camera_Name")
.First()
.Element("LocalPosition");
var screenPosition = xdoc.Descendants("Screen")
.First()
.Element("LocalPosition");
//parsing and displaying data
int cameraX = int.Parse(cameraPosition.Attribute("X").Value);
int cameraY = int.Parse(cameraPosition.Attribute("Y").Value);
Console.WriteLine ("camera pos: X={0}; Y={1}", cameraX, cameraY);
int screenX = int.Parse(screenPosition.Attribute("X").Value);
int screenY = int.Parse(screenPosition.Attribute("Y").Value);
Console.WriteLine ("screen pos: X={0}; Y={1}", screenX, screenY);
prints:
screen pos: X=12; Y=81
camera pos: X=354; Y=108

If you use XPath you can target the nodes and retrieve them in to an iterator.
http://msdn.microsoft.com/en-us/library/0ea193ac.aspx

C# How to modify xml attributes based on searched string

I want to find all instances of an element attribute that contains a certain string and change it.
Sample xml would be:
<system>
<template>
<url address="http://localhost:7888/Application/basic" />
<url address="http://localhost:7997/sdk/basic" />
<url address="http://localhost:5855/htm/ws" />
<url address="net.tcp://localhost:5256/htm" />
<url address="http://localhost:5215/htm/basic" />
<url address="http://localhost:5235/htm/ws" />
<url address="net.tcp://localhost:5256/htm" />
<url address="http://localhost:5252/Projectappmgr/basic"/>
<url address="http://localhost:5295/Projectappmgr/ws" />
</template>
</system>
I have the following code:
XmlNodeList nodelist = doc.GetElementsByTagName("url");
foreach (XmlNode node in nodelist)
{
if (node.Attributes["address"].Value.Contains("localhost"))
{
string origValue = node.Attributes["address"].Value;
string modValue = String.Empty;
Console.WriteLine("Value of original address is: " + origValue);
modValue = origValue.Replace("localhost", "newURLName");
Console.WriteLine("Value of modified address is: " + modValue);
node.Attributes["address"].InnerText = modValue;
}
}
This modifies the address' value as expected.
<url address="http://newURLName:7888/Application/basic" />
But, what I really want is to replace the entire string "localhost:7888" with newURLName. Is there a way to specify the port numbers as wild characters since they will not all be the same as in the example xml block?
I know I need the replace value to be "localhost:xxxx", but "xxxx" is different in each instance and I'm sort of drawing a blank at the moment.
Thanks

Regular expressions should help here:
modValue = Regex.Replace(url, #"localhost(:\d+){0,1}", newUrlName)
Here you can find more exapmles. Also I would recommend using Expresso to get familiar with Regex.

You could use xpath to find nodes which contain your search string and then use UriBuilder class to modify your URLs:
var xdoc = XDocument.Parse(xml);
var nodes = xdoc.XPathSelectElements("//url[contains(#address, 'localhost')]");
foreach (var node in nodes)
{
var ub = new UriBuilder(node.Attribute("address").Value);
ub.Host = "newURLName";
node.SetAttributeValue("address", ub.ToString());
}
This will get you
<system>
<template>
<url address="http://newURLName:7888/Application/basic" />
<url address="http://newURLName:7997/sdk/basic" />
<url address="http://newURLName:5855/htm/ws" />
<url address="net.tcp://newURLName:5256/htm" />
<url address="http://newURLName:5215/htm/basic" />
<url address="http://newURLName:5235/htm/ws" />
<url address="net.tcp://newURLName:5256/htm" />
<url address="http://newURLName:5252/Projectappmgr/basic" />
<url address="http://newURLName:5295/Projectappmgr/ws" />
</template>
</system>
from your XML example even without using of regex.

Replace
modValue = origValue.Replace("localhost", "newURLName");
by
modValue = Regex.Replace(origValue, "localhost(:[0-9]+){0,1}", "newURLName");

An alternative to regex would be to use a strongly typed Uri object and the UriBuilder.
var origValue = new Uri(node.Attributes["address"].Value);
var uriBuilder = new UriBuilder(origValue);
uriBuilder.Host = newHost;
uriBuilder.Port = newPort;
modValue = uriBuilder.Uri;
This may seem long winded but it is an alternative to a simple regex, gives you something that is strongly typed and allows you to validate that the Uri is actually valid (see the Uri class methods / properties). You may also be able to do the host and port number in one step, I have not played around with that.

How to grab children from xml file as a string

I am looking for an occurance of a certain tag in my xml file. If i find an occurance then i want to get its immediate children tags (not their child tags)
Is this possible? If so what do i need to look in to ?
Thanks
<Footballer>
<Player>
<Number />
<Team>
<Division />
<Position />
</Team>
<Country />
<Birthdate />
</Player>
</Footballer>
if player was the input for example then the tags Number, Team, Country Birthdate would be returned

You can try to use linq to xml:
var doc = XDocument.Load(xmlFilePath);
List<string> urlList = doc.Descendants("yourparent");
.Select(x => insert value you want to select).ToList();