Selecting XML nodes?

Selecting XML nodes? - c#

I have a large XML file with a lot of these file nodes:
<File>
<Component>Main</Component>
<Path>C:\Logs\Main</Path>
<FileName>logfile1.log</FileName>
</File>
In my C# program I want to select a node with a certain file name, eg in the above example I would like to select the File node where the FileName is logfile1.log. Is there a way I can do this in my C#, or maybe I need to make the FileName as an attribute for each File node, e.g.:
<File name="logfile1.log">...</File>
Could anybody advise me on the best practise here? Thanks for any help!

Using query syntax;
var xml = XDocument.Load("input.xml");
var node = (from file in xml.Descendants("File")
where (string)file.Element("FileName") == "logfile1.log"
select file).Single();
Obviously the call to force the query (Single() in this case) should be swapped out to suit your own app.

XPath query would be a good choice for that. You can use xpath to search for either an element name or an attribute name.
something like:
var doc = new XPathDocument(path);
var xpath = doc.CreateNavigator();
//with element
var node = xpath.SelectSingleNode("//File[FileName='logfile1.log']");
//or with attribute
var node = xpath.SelectSingleNode("//File[#name='logfile1.log']");
Or, if there could be more than one you can use Select to find multiple matches and then iterate them.
var node = xpath.Select("//File...");

var doc = new XmlDocument();
doc.LoadXml(xml); // or Load(path)
var node = doc.SelectSingleNode("//File/FileName[.='logfile1.log']");
(see XPath selection by innertext)
or
var doc = XDocument.Load(path);
var node = doc.Elements("Path").FirstOrDefault(e => (string)e.Element("FileName") == "logfile1.log");

Related

Selecting value from first xml child node

I have an XML file that contains multiple URLs for different image file sizes, and I'm trying to get a single url to load into a picture box. My issue is that the child nodes are named similarly, and the parent nodes are named similarly as well. For example, I want to pull the first medium image (ending in SL160_.jpg). See below for XML code
<Items>
<SmallImage>
<URL>http://ecx.images-amazon.com/images/I/51TAL%2Bn7AqL._SL75_.jpg</URL>
</SmallImage>
<MediumImage>
<URL>http://ecx.images-amazon.com/images/I/51TAL%2Bn7AqL._SL160_.jpg</URL>
</MediumImage>
<LargeImage>
<URL>http://ecx.images-amazon.com/images/I/51TAL%2Bn7AqL.jpg</URL>
</LargeImage>
<MediumImage>
<URL>http://ecx.images-amazon.com/images/I/51TAL%2Bn7AqL._SL162_.jpg</URL>
</MediumImage>
<LargeImage>
<URL>http://ecx.images-amazon.com/images/I/51TAL%2Bn7AqL.jpg</URL>
</LargeImage>
</Items>
I've tried using GetElementsByTag, as well as trying to call something like doc.SelectSingleNode("LargeImage").SelectSingleNode("URL").InnerText, and GetElementByID. All of these have given me an Object set to null reference exception.
What can I do to specify that I want the url from the first found MediumImage node?

Use LinqToXML，It is rather simple
string xml = #"<Items>
<SmallImage>
<URL>http://ecx.images-amazon.com/images/I/51TAL%2Bn7AqL._SL75_.jpg</URL>
</SmallImage>
<MediumImage>
<URL>http://ecx.images-amazon.com/images/I/51TAL%2Bn7AqL.01_SL160_.jpg</URL>
</MediumImage>
<LargeImage>
<URL>http://ecx.images-amazon.com/images/I/51TAL%2Bn7AqL.jpg</URL>
</LargeImage>
<MediumImage>
<URL>http://ecx.images-amazon.com/images/I/51TAL%2Bn7AqL.02_SL162_.jpg</URL>
</MediumImage>
<LargeImage>
<URL>http://ecx.images-amazon.com/images/I/51TAL%2Bn7AqL.jpg</URL>
</LargeImage>
</Items>";
XElement root = XElement.Parse(xml);
var ele = root.Elements("MediumImage").Where(e => e.Element("URL").Value.EndsWith("SL160_.jpg")).FirstOrDefault();
Console.WriteLine(ele);

In addition to Sky Fang's answer, I think the OP wants this:
var firstMedImg = root.Elements("MediumImage").First();
var imgUrl = firstMedImg.Element("URL").Value;

XmlDocument doc = new XmlDocument();
// PATH TO YOUR DOCUMENT
doc.Load("daco.xml");
// Select LIST ALL ELEMENTS SmallImage,MediumImage,LargeImage
XmlNodeList listOfAllImageElements = doc.SelectNodes("/Items/*");
foreach (XmlNode imageElement in listOfAllImageElements)
{
// Select URL ELEMENT
XmlNode urlElement= node.SelectSingleNode("URL");
System.Console.WriteLine(urlElement.InnerText);
}
Console.ReadLine();
If you want to select multiple url's
XmlDocument doc = new XmlDocument();
// PATH TO YOUR DOCUMENT
doc.Load("daco.xml");
// Select LIST ALL ELEMENTS SmallImage,MediumImage,LargeImage
XmlNodeList listOfAllImageElements = doc.SelectNodes("/Items/*");
foreach (XmlNode imageElement in listOfAllImageElements)
{
// Select URL's ELEMENTs
XmlNodeList listOfAllUrlElements = imageElement.SelectNodes("URL");
foreach (XmlNode urlElement in listOfAllUrlElements)
{
System.Console.WriteLine(urlElement.InnerText);
}
}
Console.ReadLine();
if you have specific namespace in your xml file
XmlDocument doc = new XmlDocument();
doc.Load("doc.xml");
XmlNamespaceManager man = new XmlNamespaceManager(doc.NameTable);
// reaplace http://schemas.microsoft.com/vs/2009/dgml with your namespace
man.AddNamespace("x", "http://schemas.microsoft.com/vs/2009/dgml");
// next you have to use x: in your path like this
XmlNodeList node = doc.SelectNodes("/x:Items/x:*, man);

How can I get a node from an XML document based on its attribute value and into an XElement object?

I need to inject some XML into a pre-existing XML file under a certain node. Here is the code I have to create my XML:
//Define the nodes
XElement dataItemNode = new XElement("DataItem");
XElement setterNodeDisplayName = new XElement("Setter");
XElement setterNodeOU = new XElement("Setter");
//Create the tree with the nodes
dataItemNode.Add(setterNodeDisplayName);
dataItemNode.Add(setterNodeOU);
//Define the attributes
XAttribute nameAttrib = new XAttribute("Name", "OrganizationalUnits");
XAttribute displayNameAttrib = new XAttribute("Property", "DisplayName");
XAttribute ouAttrib = new XAttribute("Property", "OU");
//Attach the attributes to the nodes
setterNodeDisplayName.Add(displayNameAttrib);
setterNodeOU.Add(ouAttrib);
//Set the values for each node
setterNodeDisplayName.SetValue("TESTING DISPLAY NAME");
setterNodeOU.SetValue("OU=funky-butt,OU=super,OU=duper,OU=TMI,DC=rompa-room,DC=pbs,DC=com");
Here is the code I have so far to load up the XML document and try to get the node that I need to insert my XML under:
//Load up the UDI Wizard XML file
XDocument udiXML = XDocument.Load("UDIWizard_Config.xml");
//Get the node that I need to append to and then append my XML to it
XElement ouNode = THIS IS WHAT I DONT KNOW HOW TO DO
ouNode.Add(dataItemNode);
Here is the XML from the existing document I am trying to work with:
<Data Name="OrganizationalUnits">
<DataItem>
<Setter Property="DisplayName">TESTING DISPLAY NAME</Setter>
<Setter Property="OU">OU=funky-butt,OU=super,OU=duper,OU=TMI,DC=rompa-room,DC=pbs,DC=com</Setter>
</DataItem>
I have multiple nodes that with the name of "Data", but I need to get the node that is , and I don't know how. Just learning how to use XML with C#.
Thank you.

This will get the first Data node with Name attribute matching OrganizationalUnits:
var ouNode = udiXML
.Descendants("Data")
.Where(n => n.Attribute("Name") != null)
.Where(n => n.Attribute("Name").Value == "OrganizationalUnits")
.First();
If your document might contain Data nodes without Name attribute, extra check for null might be necessary.
Note that you can achieve the same result with XPath (this will select root Data node, you can get DataItem node using Element method):
var ouNode = udiXML.XPathSelectElement("//Data[#Name = 'OrganizationalUnits']");

Get certain xml node and save the value

Considering the following XML:
<Stations>
<Station>
<Code>HT</Code>
<Type>123</Type>
<Names>
<Short>H'bosch</Short>
<Middle>Den Bosch</Middle>
<Long>'s-Hertogenbosch</Long>
</Names>
<Country>NL</Country>
</Station>
</Stations>
There are multiple nodes. I need the value of each node.
I've got the XML from a webpage (http://webservices.ns.nl/ns-api-stations-v2)
Login (--) Pass (--)
Currently i take the XML as a string and parse it to a XDocument.
var xml = XDocument.Parse(xmlString);
foreach (var e in xml.Elements("Long"))
{
var stationName = e.ToString();
}

You can retrieve "Station" nodes using XPath, then get each subsequent child node using more XPath. This example isn't using Linq, which it looks like you possibly are trying to do from your question, but here it is:
XmlDocument xml = new XmlDocument();
xml.Load(xmlStream);
XmlNodeList stations = xml.SelectNodes("//Station");
foreach (XmlNode station in stations)
{
var code = station.SelectSingleNode("Code").InnerXml;
var type = station.SelectSingleNode("Type").InnerXml;
var longName = station.SelectSingleNode("Names/Long").InnerXml;
var blah = "you should get the point by now";
}
NOTE: If your xmlStream variable is a String, rather than a Stream, use xml.LoadXml(xmlStream); for line 2, instead of xml.Load(xmlStream). If this is the case, I would also encourage you to name your variable to be more accurately descriptive of the object you're working with (aka. xmlString).

This will give you all the values of "Long" for every Station element.
var xml = XDocument.Parse(xmlStream);
var longStationNames = xml.Elements("Long").Select(e => e.Value);

NodeList.SelectSingleNode() syntax

Having problems getting NodeList.SelectSingleNode() to work properly.
My XML looks like this:
<?xml version="1.0" encoding="ISO-8859-1" standalone="yes"?>
<inm:Results xmlns:inm="http://www.namespace.com/1.0">
<inm:Recordset setCount="18254">
<inm:Record setEntry="0">
<!-- snip -->
<inm:Image>fileName.jpg</inm:Image>
</inm:Record>
</inm:Recordset>
</inm:Results>
The data is a long series of <inm:Record> entries.
I open the doc and get create a NodeList object based on "inm:Record". This works great.
XmlDocument xdoc = new XmlDocument();
xdoc.Load(openFileDialog1.FileName);
XmlNodeList xRecord = xdoc.GetElementsByTagName("inm:Record");
I start looping through the NodeList using a for loop. Before I process a given entry, I want to check and see if the <inm:Image> is set. I thought it would be super easy just to do
string strImage = xRecord[i].SelectSingleNode("inm:Image").InnerText;
My thinking being, "For the XRecord that I'm on, go find the <inm:Image> value ...But this doesn't work as I get the exception saying that I need a XmlNameSpaceManager. So, I tried to set that up but could never get the syntax right.
Can someone show me how to use the correct XmlNameSpaceManager syntax in this case.
I've worked around the issue for now by looping through all of the childNodes for a given xRecord, and checking the tag once I loop around to it. I would like to check that value first to see if I need to loop over that <inm:Record> entry at all.

No need to loop through all the Record elements, just use XPath to specify the subset that you want:
XmlDocument xdoc = new XmlDocument();
xdoc.Load(openFileDialog1.FileName);
XmlNamespaceManager manager = new XmlNamespaceManager(xdoc.NameTable);
manager.AddNamespace("inm", "http://www.inmagic.com/webpublisher/query");
XmlNodeList nodes = xdoc.SelectNodes("/inm:Results/inm:Recordset/inm:Record[inm:Image != '']", manager);

Using the LINQ to XML libraries, here's an example for retrieving that said node's value:
XDocument doc = XDocument.Load(openFileDialog1.FileName);
List<XElement> docElements = doc.Elements().ToList();
XElement results = docElements.Elements().Where(
ele => ele.Name.LocalName == "Results").First();
XElement firstRecord = results.Elements().Where(
ele => ele.Name.LocalName == "Record").First();
XElement recordImage = firstRecord .Elements().Where(
ele => ele.Name.LocalName == "Image").First();
string imageName = recordImage.Value;
Also, by the way, using Hungarian notation for a type-checked language is overkill. You don't need to prepend string variables with str when it will always be a string.

XmlNamespaceManager nsMgr = new XmlNamespaceManager(xdoc.NameTable);
string strImage = xRecord[i].SelectSingleNode("inm:Image",nsMgr).InnerText;
Should do it.

Using this Xml library, you can get all the records that have an Image child element with this:
XElement root = XElement.Load(openFileDialog1.FileName);
XElement[] records = root.XPath("//Record[Image]").ToArray();
If you want to be sure that the Image child contains a value, it can be expressed like this:
XElement[] records = root.XPath("//Record[Image != '']").ToArray();

XPathSelectElements returns null

Load function is already defined in xmlData class
public class XmlData
{
public void Load(XElement xDoc)
{
var id = xDoc.XPathSelectElements("//ID");
var listIds = xDoc.XPathSelectElements("/Lists//List/ListIDS/ListIDS");
}
}
I'm just calling the Load function from my end.
XmlData aXmlData = new XmlData();
string input, stringXML = "";
TextReader aTextReader = new StreamReader("D:\\test.xml");
while ((input = aTextReader.ReadLine()) != null)
{
stringXML += input;
}
XElement Content = XElement.Parse(stringXML);
aXmlData.Load(Content);
in load function,im getting both id and and listIds as null.
My test.xml contains
<SEARCH>
<ID>11242</ID>
<Lists>
<List CURRENT="true" AGGREGATEDCHANGED="false">
<ListIDS>
<ListID>100567</ListID>
<ListID>100564</ListID>
<ListID>100025</ListID>
<ListID>2</ListID>
<ListID>1</ListID>
</ListIDS>
</List>
</Lists>
</SEARCH>

EDIT: Your sample XML doesn't have an id element in the namespace with the nss alias. It would be <nss:id> in that case, or there'd be a default namespace set up. I've assumed for this answer that in reality the element you're looking for is in the namespace.
Your query is trying to find an element called id at the root level. To find all id elements, you need:
var tempId = xDoc.XPathSelectElements("//nss:id", ns);
... although personally I'd use:
XDocument doc = XDocument.Parse(...);
XNamespace nss = "http://schemas.microsoft.com/SQLServer/reporting/reportdesigner";
// Or use FirstOrDefault(), or whatever...
XElement idElement = doc.Descendants(nss + "id").Single();
(I prefer using the query methods on LINQ to XML types instead of XPath... I find it easier to avoid silly syntax errors etc.)
Your sample code is also unclear as you're using xDoc which hasn't been declared... it helps to write complete examples, ideally including everything required to compile and run as a console app.

I am looking at the question 3 hours after it was submitted and 41 minutes after it was (last) edited.
There are no namespaces defined in the provided XML document.
var listIds = xDoc.XPathSelectElements("/Lists//List/ListIDS/ListIDS");
This XPath expression obviously doesn't select any node from the provided XML document, because the XML document doesn't have a top element named Lists (the name of the actual top element is SEARCH)
var id = xDoc.XPathSelectElements("//ID");
in load function,im getting both id and and listIds as null.
This statement is false, because //ID selects the only element named ID in the provided XML document, thus the value of the C# variable id is non-null. Probably you didn't test thoroughly after editing the XML document.
Most probably the original ID element belonged to some namespace. But now it is in "no namespace" and the XPath expression above does select it.

string xmldocument = "<response xmlns:nss=\"http://schemas.microsoft.com/SQLServer/reporting/reportdesigner\"><action>test</action><id>1</id></response>";
XElement Content = XElement.Parse(xmldocument);
XPathNavigator navigator = Content.CreateNavigator();
XmlNamespaceManager ns = new XmlNamespaceManager(navigator.NameTable);
ns.AddNamespace("nss", "http://schemas.microsoft.com/SQLServer/reporting/reportdesigner");
var tempId = navigator.SelectSingleNode("/id");

The reason for the null value or system returned value is due to the following
var id = xDoc.XPathSelectElements("//ID");
XpathSElectElements is System.xml.linq.XElment which is linq queried date. It cannot be directly outputed as such.
To Get individual first match element
use XPathSelectElement("//ID");
You can check the number of occurrences using XPathSelectElements as
var count=xDoc.XPathSelectElements("//ID").count();
you can also query the linq statement as order by using specific conditions
Inorder to get node value from a list u can use this
foreach (XmlNode xNode in xDoc.SelectNodes("//ListIDS/ListID"))
{
Console.WriteLine(xNode.InnerText);
}
For Second list you havnt got the value since, the XPath for list items is not correct

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C# (C-Sharp) is a programming language developed by Microsoft that runs on the .NET Framework.

Selecting XML nodes? - c#

Using query syntax; var xml = XDocument.Load("input.xml"); var node = (from file in xml.Descendants("File") where (string)file.Element("FileName") == "logfile1.log" select file).Single(); Obviously the call to force the query (Single() in this case) should be swapped out to suit your own app.

Related

Selecting value from first xml child node

How can I get a node from an XML document based on its attribute value and into an XElement object?

Get certain xml node and save the value

NodeList.SelectSingleNode() syntax

XPathSelectElements returns null

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