Develop Reference

How do I select items in an XDocument?

In the XML below, I'm trying to retrieve all the trkpt items so that I can perform a task with the lat / lon attribute values. I thought LINQ to XML would be easiest approach but I can't get any results to be returned in the foreach loop. What am I doing wrong?
This code is in the Main() method of a console app:
var filename = #"C:\temp\sample_output.gpx";
var xDoc = XDocument.Load(filename);
XNamespace xmlns = "http://www.topografix.com/GPX/1/1";
XNamespace gpxtpx = "http://www.garmin.com/xmlschemas/TrackPointExtension/v1";
XNamespace wptx1 = "http://www.garmin.com/xmlschemas/WaypointExtension/v1";
XNamespace gpxx = "http://www.garmin.com/xmlschemas/GpxExtensions/v3";
XNamespace gpxtrkx = "http://www.garmin.com/xmlschemas/TrackStatsExtension/v1";
foreach (var item in xDoc.Descendants(gpxtpx + "trkpt"))
{
Console.WriteLine(item.Element(gpxtpx + "trkpt").Value);
}
Console.Read();
XML data I'm trying to process with the above code. Lat / Lon values modified.
<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<gpx xmlns="http://www.topografix.com/GPX/1/1"
xmlns:gpxx="http://www.garmin.com/xmlschemas/GpxExtensions/v3"
xmlns:gpxtrkx="http://www.garmin.com/xmlschemas/TrackStatsExtension/v1"
xmlns:wptx1="http://www.garmin.com/xmlschemas/WaypointExtension/v1"
xmlns:gpxtpx="http://www.garmin.com/xmlschemas/TrackPointExtension/v1"
creator="Oregon 600" version="1.1"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.topografix.com/GPX/1/1
http://www.topografix.com/GPX/1/1/gpx.xsd
http://www.garmin.com/xmlschemas/GpxExtensions/v3
http://www8.garmin.com/xmlschemas/GpxExtensionsv3.xsd
http://www.garmin.com/xmlschemas/TrackStatsExtension/v1
http://www8.garmin.com/xmlschemas/TrackStatsExtension.xsd
http://www.garmin.com/xmlschemas/WaypointExtension/v1
http://www8.garmin.com/xmlschemas/WaypointExtensionv1.xsd
http://www.garmin.com/xmlschemas/TrackPointExtension/v1
http://www.garmin.com/xmlschemas/TrackPointExtensionv1.xsd">
<metadata>
<link href="http://www.garmin.com">
<text>Garmin International</text>
</link>
<time>2016-04-18T01:19:07Z</time>
</metadata>
<trk>
<name>2016-04-17 20:19:01</name>
<extensions>
<gpxx:TrackExtension>
<gpxx:DisplayColor>Magenta</gpxx:DisplayColor>
</gpxx:TrackExtension>
</extensions>
<trkseg>
<trkpt lat="44.123" lon="-89.123">
<ele>343.61</ele>
<time>2016-04-17T22:53:34Z</time>
</trkpt>
<trkpt lat="44.123" lon="-89.123">
<ele>343.58</ele>
<time>2016-04-17T22:53:35Z</time>
</trkpt>
<trkpt lat="44.123" lon="-89.123">
<ele>343.56</ele>
<time>2016-04-17T22:53:36Z</time>
</trkpt>
<trkpt lat="44.123" lon="-89.123">
<ele>343.55</ele>
<time>2016-04-17T22:53:37Z</time>
</trkpt>
<trkpt lat="44.123" lon="-89.123">
<ele>343.62</ele>
<time>2016-04-17T22:53:38Z</time>
</trkpt>
</trkseg>
</trk>
</gpx>

You're using the wrong namespace. The default namespace of the elements (including trkpt) is http://www.topografix.com/GPX/1/1, due to this:
xmlns="http://www.topografix.com/GPX/1/1"
I would strongly recommend that you change your variable name to gpxNs to indicate its value, then use it:
XNamespace gpxNs = "http://www.topografix.com/GPX/1/1";
...
foreach (var item in xDoc.Descendants(gpxNs + "trkpt"))

You can do it with XML Linq
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;
using System.Xml.Linq;
namespace ConsoleApplication1
{
class Program
{
const string FILENAME = #"c:\temp\test.xml";
static void Main(string[] args)
{
XDocument doc = XDocument.Load(FILENAME);
XElement trkseg = doc.Descendants().Where(x => x.Name.LocalName == "trkseg").FirstOrDefault();
XNamespace ns = trkseg.Name.Namespace;
var l_l = trkseg.Elements(ns + "trkpt").Select(x => new
{
lat = x.Attribute("lat").Value,
lon = x.Attribute("lon").Value
}).ToList();
}
}
}

Edit an element inside cdata

I'm trying to edit an element in the following xml, but I'm not sure how to deal with the cdata code... the element I want to edit is FileID
<Import>
<MethodParameters>
<messageXml><![CDATA[
<Message>
<ImportRequest Entity="Users">
<File Name="XXXXXX" Type="Xml" FileID="TestM-00" TotalPartialFiles="1" PartialSequence="1" Md5="">
<![CDATA[
<ImportUserList>
<ImportUser UserName="TestM01" FirstName="TestM01" MiddleName="TestM01" LastName="TestM01" Active="true" Email="TestM01#gmail.com" ExternalId="TestM01"/>
<ImportUser UserName="TestM02" FirstName="TestM02" MiddleName="TestM02" LastName="TestM02" Active="true" Email="TestM02#gmail.com" ExternalId="TestM02"/>
</ImportUserList>
]]]]><![CDATA[>
</File >
</ImportRequest>
</Message>
]]></messageXml>
</MethodParameters>
</Import>
I have something like this in C#, but I'm not sure how to update the Users.xml file, because I know that AdminNode is in the second document
var doc = new XmlDocument();
doc.Load("E:\\Users.xml");
XmlNode node = doc.SelectSingleNode("/Import/MethodParameters/messageXml").FirstChild;
string newID = Guid.NewGuid().ToString();
XmlNodeList xmlRootNode = doc.GetElementsByTagName("messageXml");
String Sxml = xmlRootNode.Item(0).InnerText;
XmlDocument xdoc = new XmlDocument();
xdoc.LoadXml(Sxml);
XmlNodeList AdminNode = xdoc.GetElementsByTagName("Message");
AdminNode.Item(0).SelectSingleNode("//ImportRequest/File/#FileID").Value = newID;
doc.Save("E:\\Users.xml");

The following code should do the trick:
string xml = #"<Import>
<MethodParameters>
<messageXml><![CDATA[
<Message>
<ImportRequest Entity=""Users"">
<File Name=""XXXXXX"" Type=""Xml"" FileID=""TestM-00"" TotalPartialFiles=""1"" PartialSequence=""1"" Md5="""">
<![CDATA[
<ImportUserList>
<ImportUser UserName=""TestM01"" FirstName=""TestM01"" MiddleName=""TestM01"" LastName=""TestM01"" Active=""true"" Email=""TestM01#gmail.com"" ExternalId=""TestM01""/>
<ImportUser UserName=""TestM02"" FirstName=""TestM02"" MiddleName=""TestM02"" LastName=""TestM02"" Active=""true"" Email=""TestM02#gmail.com"" ExternalId=""TestM02""/>
</ImportUserList>
]]]]><![CDATA[>
</File>
</ImportRequest>
</Message>
]]></messageXml>
</MethodParameters>
</Import>";
var newID = Guid.NewGuid().ToString();
var xDoc = XDocument.Parse(xml);
var messageNode = xDoc.XPathSelectElement(".//messageXml");
var innerDoc = XDocument.Parse(messageNode.Value);
innerDoc.XPathSelectElement(".//ImportRequest/File").Attribute("FileID").Value = newID;
messageNode.ReplaceAll(new XCData(innerDoc.ToString()));
It's pretty dirty now, but at least it produces the expected output:
<Import>
<MethodParameters>
<messageXml><![CDATA[<Message>
<ImportRequest Entity="Users">
<File Name="XXXXXX" Type="Xml" FileID="609bead3-3295-4d68-a07f-1ee47db756fd" TotalPartialFiles="1" PartialSequence="1" Md5="">
<![CDATA[
<ImportUserList>
<ImportUser UserName="TestM01" FirstName="TestM01" MiddleName="TestM01" LastName="TestM01" Active="true" Email="TestM01#gmail.com" ExternalId="TestM01"/>
<ImportUser UserName="TestM02" FirstName="TestM02" MiddleName="TestM02" LastName="TestM02" Active="true" Email="TestM02#gmail.com" ExternalId="TestM02"/>
</ImportUserList>
]]]]><![CDATA[>
</File>
</ImportRequest>
</Message>]]></messageXml>
</MethodParameters>
</Import>

Cannot replace child XmlDocument [duplicate]

This question already has an answer here:
Error: "The node to be inserted is from a different document context"
(1 answer)
Closed 8 years ago.
I am using XML as discuss forum in ASP.NET. I am trying to add functionality for updating comments. My XML structure is this:
<forum>
<author id="1">
<comment id="0" idUser="19">
<name>....</name>
<date>....</date>
<message>...</message>
</comment>
<comment id="1" idUser="4">
....
</comment>
</author>
<author id="2">
....
</author>
</forum>
And my code is:
protected void btnEditComment_Click(object sender, EventArgs e)
{
if (messageTxb.Text!="" && nameTxb.Text!="")
{
XmlDocument doc = new XmlDocument();
doc.Load(Server.MapPath("~/App_Data/forum.xml"));
XmlNode newComment = (XmlNode)Session["Comment"];
XmlNode oldComment = doc.SelectSingleNode(string.Format("//author[#id={0}]/comment[#id={1}]",Request.QueryString["id"],newComment.Attributes["id"].Value));
newComment.ChildNodes[0].InnerText = nameTxb.Text.Trim();
newComment.ChildNodes[1].InnerText = string.Format("{0:D}", DateTime.Now);
newComment.ChildNodes[2].InnerText = messageTxb.Text.Trim();
oldComment.ParentNode.ReplaceChild(newComment, oldComment);
doc.Save(Server.MapPath("~/App_Data/forum.xml"));
Repeater1.DataBind();
Response.Redirect(string.Format("~/user/Autor.aspx?id={0}", Request.QueryString["id"]));
}
}
I get error
'The node to be inserted is from a different document context.'
It raises when I am trying to use the replaceChild method.

try to replace this row:
oldComment.ParentNode.ReplaceChild(doc.ImportNode(newComment, true), oldComment);

XmlDocument and getting specific Attributes using xPath

I have seen a couple of examples on here where Xpath is used in conjunction with XmlDocument to get a specific attribute from an XmlDocument Node.... Example
Console.WriteLine(xmlDocument.SelectSingleNode("//dataTemplateSpecification/templates/template/elements/element/#name").Value.ToString());
For some reason I am getting a "Object reference not set to an instance of an object." exception. Whenever I run across that particular line of code. I have a little test app that I have set up to test out different things before I put them into my main project...
Here is the code for that...
namespace ReadXml
{
class Program
{
static void Main(string[] args)
{
//string fulXmlPath = System.Web.Hosting.HostingEnvironment.MapPath("~/App_Data/templateExample.xml");
XDocument xDocument = XDocument.Load("C:\\Users\\derekww\\Documents\\XML Documents\\templateExample.xml");
XElement elem = xDocument.Element("dataTemplateSpecification"); ;
XmlDocument xmlDocument = new XmlDocument();
StreamReader file = new StreamReader("C:\\Users\\derekww\\Documents\\XML Documents\\templateExample.xml");
xmlDocument.Load(file);
//XmlDocument theDoc = new XmlDocument();
//using (var xmlReader = xDocument.CreateReader())
//{
// xmlDocument.Load(xmlReader);
//}
//Console.WriteLine(elem.ToString());
XmlNode xNode = xmlDocument.SelectSingleNode("//dataTemplateSpecification/templates/template/elements/element");
Console.WriteLine("WORK PLEASE!!!! {0}", xNode.Value.ToString());
//Console.WriteLine(xmlDocument.SelectSingleNode("//dataTemplateSpecification/templates/template/elements/element/#name").Value.ToString());
//Console.WriteLine("This better Work>>>> {0}", xmlDocument.Attributes["/dataTemplateSpecification/templates/template/elements/element/#name"].Value);
Console.ReadLine();
//Console.WriteLine("This better Work>>>> {0}", xmlDocument.SelectSingleNode("//dataTemplateSpecification/templates/template/elements/element/#name").Value);
//foreach (String AttVal in xmlDocument.SelectSingleNode("//dataTemplateSpecification/templates/template/elements/element/#name").Value)
{
//Console.WriteLine("This better Work>>>> {0}", AttVal);
}
}
}
}
Here is part of the XML that I used...
<?xml version="1.0" encoding="utf-8"?>
<dataTemplateSpecification id="id1" name="name1" xmlns="http://EADIS.upmc.com /DataTemplateSpecification.xsd">
<description xmlns="">
<html>text</html>
</description>
<templates xmlns="">
<template>
<elements>
<element id="element0" name="PatientId" display="Patient ID" dataType="String" value="0101010111111" visable="false" readOnly="true">
<validation>
<rules>
<rule id="0" test="#element0.value == ''">
<fail>
<html><b>Patient ID is null, value must be present</b></html>
</fail>
</rule>
</rules>
</validation>
</element>
</elements>
</template>
<templates>
I just showed you the part that you need to understand the xml structure. I assure you that it is well formed. I think I asked this question before but somehow or the other it didn't get posted (maybe I forgot, who knows). Any help with this would be greatly appreciated. If I come up with a reason for why it isn't working I will be sure to let you guys know.
Thank You.

Why can't you use this XPath:
xmlDocument.SelectSingleNode("//templates/template/elements/element/#name").Value

You need to specify the namespace of the XML file in your code.
See here for more info: How to select xml root node when root node has attribute?

Getting "<kml:..." everywhere, updating a Kml file

I'm reading in a Kml file, changing the placemarks' names, and saving it again.
var KmlFile = XDocument.Load("C:\\Inetpub\\wwwroot\\GeotagService\\Kml\\Photographs.kml");
XNamespace KmlNamespace = "http://www.opengis.net/kml/2.2";
// find the Placemarks in the Photos folder
IEnumerable<XElement> Placemarks = KmlFile.Element(KmlNamespace + "kml").Element(KmlNamespace + "Document").Element(KmlNamespace + "Folder").Elements(KmlNamespace + "Placemark");
foreach (XElement p in Placemarks){
p.Element(KmlNamespace + "name").Value = "testing";
}
KmlFile.Save("C:\\Inetpub\\wwwroot\\GeotagService\\Kml\\Photographs.kml");
When I save it however, every element is prefixed with <kml:, like this:
<kml:Folder>
<kml:name>Photos</kml:name>
<kml:open>1</kml:open>
<kml:Placemark>
<kml:name>testing</kml:name>
<kml:LookAt>
<kml:longitude>-10.02717694938161</kml:longitude>
<kml:latitude>53.48672543547379</kml:latitude>
<kml:altitude>0</kml:altitude>
</kml:LookAt>
<kml:styleUrl>#msn_ylw-pushpin1</kml:styleUrl>
<kml:Point>
<kml:coordinates>-10.02867619360582,53.48651240326751,0</kml:coordinates>
</kml:Point>
</kml:Placemark>...
Tomalak's comment on this question about blank xmlns gives me a clue that it might be inconsistencies between the namespaces of the document and the elements, but I can't see how I'm doing that. Anyone know?
EDIT: Original document (in part):
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2" xmlns:kml="http://www.opengis.net/kml/2.2" xmlns:atom="http://www.w3.org/2005/Atom">
<Document>
<name>Connemara.net Photographs</name>
<open>1</open>
<Style id="sh_ylw-pushpin0">
<IconStyle>
<scale>1.3</scale>
<Icon>
<href>http://maps.google.com/mapfiles/kml/pushpin/ylw-pushpin.png</href>
</Icon>
<hotSpot x="20" y="2" xunits="pixels" yunits="pixels"/>
</IconStyle>
</Style>
<Folder>
<name>Photos</name>
<open>1</open>
<Placemark>
<name>Id:579</name>
<LookAt>
<longitude>-10.02717694938161</longitude>
<latitude>53.48672543547379</latitude>
<altitude>0</altitude>
<range>213.2931913230747</range>
<tilt>75.17546328115256</tilt>
<heading>69.89736514305363</heading>
<altitudeMode>relativeToGround</altitudeMode>
<gx:altitudeMode>relativeToSeaFloor</gx:altitudeMode>
</LookAt>
<styleUrl>#msn_ylw-pushpin1</styleUrl>
<Point>
<coordinates>-10.02867619360582,53.48651240326751,0</coordinates>
</Point>
</Placemark>
...
</Folder>
</Document>
</kml>

Got it - the problem is that the original document starts like this:
<kml xmlns="http://www.opengis.net/kml/2.2"
xmlns:gx="http://www.google.com/kml/ext/2.2"
xmlns:kml="http://www.opengis.net/kml/2.2"
xmlns:atom="http://www.w3.org/2005/Atom">
LINQ to XML sees that there's a specific alias for the KML namespace, so uses that. If you remove that attribute, it works fine:
var explicitNs = KmlFile.Root.Attribute(XNamespace.Xmlns + "kml");
if (explicitNs != null)
{
explicitNs.Remove();
}

You need to use a namespace manager. Here's an example using XPath to select the necessary tags and then update their value:
using System;
using System.Xml;
using System.Xml.Linq;
using System.Xml.XPath;
class Program
{
static void Main(string[] args)
{
var kml = XDocument.Load("test.kml");
var ns = new XmlNamespaceManager(new NameTable());
ns.AddNamespace("kml", "http://www.opengis.net/kml/2.2");
var names = kml.XPathSelectElements("//kml:Placemark/kml:name", ns);
foreach (var name in names)
{
name.Value = "testing";
}
kml.Save("test.kml");
}
}