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How to find nodes in an XML

I have loaded the following XML file using xml.Load("myfile.xml"); where xml is of type XmlDocument:
<?xml version="1.0" encoding="ISO-8859-1"?>
<DTE xmlns="http://www.sii.cl/SiiDte" version="1.0">
<Documento ID="E000000005T033F0114525415">
<Encabezado>
<IdDoc>
<TipoDTE>33</TipoDTE>
<Folio>114525415</Folio>
<FchEmis>2021-11-02</FchEmis>
<FmaPago>1</FmaPago>
<FchVenc>2021-11-02</FchVenc>
</IdDoc>
</Encabezado>
</Documento>
</DTE>
How can I get Folionode?
I have tried with:
xml.DocumentElement.SelectSingleNode("/DTE/Documento/Encabezado/IdDoc/Folio");
xml.DocumentElement.SelectNodes("DTE/Documento/Encabezado/IdDoc/Folio")
xml.DocumentElement.SelectSingleNode("//DTE/Documento/Encabezado/IdDoc/Folio");
xml.DocumentElement.SelectSingleNode("/Documento/Encabezado/IdDoc/Folio");
xml.DocumentElement.SelectSingleNode("Documento/Encabezado/IdDoc/Folio");
xml.DocumentElement.SelectSingleNode("/Encabezado/IdDoc/Folio");
xml.DocumentElement.SelectNodes("/DTE/Documento/Encabezado/IdDoc/Folio")
when I debug xml.DocumentElement I see that the element is DTE so I think xml.DocumentElement.SelectSingleNode("Documento/Encabezado/IdDoc/Folio") should do it.
When I get xml.DocumentElement.FirstChild I get Documento node.
With xml.DocumentElement.FirstChild.FirstChild I get Encabezado node.
With xml.DocumentElement.FirstChild.FirstChild.FirstChild I get IdDoc node.
If I use xml.DocumentElement.FirstChild.FirstChild.FirstChild.SelectSingleNode("Folio"), returned value is null.
If I use xml.DocumentElement.FirstChild.FirstChild.FirstChild.ChildNodes, I get the 5 elements.
Then I could use xml.DocumentElement.FirstChild.FirstChild.FirstChild.ChildNodes[1].InnerText to get Folio value.
I can traverse the XML but, how can I do it to get the element directly?
Thanks
Jaime

It is better to use LINQ to XML API for your task. It is available in the .Net Framework since 2007.
The provided XML has a default namespace. It needs to be declared and used, otherwise it is imposable to find any XML element.
c#
void Main()
{
const string filename = #"e:\Temp\jstuardo.xml";
XDocument xdoc = XDocument.Load(filename);
XNamespace ns = xdoc.Root.GetDefaultNamespace();
string Folio = xdoc.Descendants(ns + "Folio")
.FirstOrDefault()?.Value;
Console.WriteLine("Folio='{0}'", Folio);
}
Output
Folio='114525415'

You can try to use the Xpath like below:
XmlDocument doc = new XmlDocument();
doc.Load("myfile.xml");
var node= doc.SelectSingleNode("Documento/Encabezado/IdDoc/[Folio='"114525415"']");

There are few ways to make things up with your issue.
So, we have our XML:
const string MyXML = #"<?xml version=""1.0"" encoding=""ISO-8859-1""?>
<DTE xmlns=""http://www.sii.cl/SiiDte"" version=""1.0"">
<Documento ID=""E000000005T033F0114525415"">
<Encabezado>
<IdDoc>
<TipoDTE>33</TipoDTE>
<Folio>114525415</Folio>
<FchEmis>2021-11-02</FchEmis>
<FmaPago>1</FmaPago>
<FchVenc>2021-11-02</FchVenc>
</IdDoc>
</Encabezado>
</Documento>
</DTE>";
And we need to get Folio node (exactly node, not just value). We can use:
XmlNamespaceManager:
to find descendant node(s) through XML namespace (xmlns) alias in XPath:
// Creating our XmlDocument instance
var xmlDocument = new XmlDocument();
xmlDocument.LoadXml(MyXML);
// Initializing XmlNamespaceManager and providing our xmlns with 'SiiDte' alias:
var xmlNamespaceManager = new XmlNamespaceManager(xmlDocument.NameTable);
xmlNamespaceManager.AddNamespace("SiiDte", "http://www.sii.cl/SiiDte");
// Declaring our simple shiny XPath:
var xPath = "descendant::SiiDte:Folio";
// If we need single (first) element:
var folio = xmlDocument.DocumentElement.SelectSingleNode(xPath, xmlNamespaceManager);
// If we need all Folios:
var folios = xmlDocument.DocumentElement.SelectNodes(xPath, xmlNamespaceManager);
XDocument and its Descendants:
from System.Xml.Linq namespace and its XDocument class, to find descendant node(s) just by their tag name <Folio>:
// If we need single (first) element:
var folio = XDocument.Parse(MyXML)
.Descendants()
.FirstOrDefault(x => x.Name.LocalName == "Folio");
// Add System.Linq using to access FirstOrDefault extension method
// If we need all Folios - just replacing FirstOrDefault with Where extension method:
var folios = XDocument.Parse(MyXML)
.Descendants()
.Where(x => x.Name.LocalName == "Folio"); // and .ToList() if you need
// Or we can use also our XML namespace to filter Descendants:
var ns = (XNamespace)"http://www.sii.cl/SiiDte";
var folios = XDocument.Parse(MyXML).Descendants(ns + "Folio");
Deserialization:
to operate not with XML or nodes, but with some class (e.g. DTE), which represents your XML schema. I'm not sure that I totally understand your XML structure, but anyway as example it could be used.
So we create our classes, which are representation of our XML:
[Serializable, XmlRoot(ElementName = nameof(DTE), Namespace = "http://www.sii.cl/SiiDte")]
public class DTE
{
[XmlAttribute("version")]
public string Version { get; set; }
[XmlElement(nameof(Documento))]
public List<Documento> Documentacion { get; set; }
}
[Serializable]
public class Documento
{
[XmlAttribute(nameof(ID))]
public string ID { get; set; }
[XmlElement(nameof(Encabezado))]
public Encabezado Encabezado { get; set; }
}
[Serializable]
public class Encabezado
{
[XmlElement(nameof(IdDoc))]
public IDDoc IdDoc { get; set; }
}
[Serializable]
public class IDDoc
{
[XmlElement(nameof(TipoDTE))]
public int TipoDTE { get; set; }
[XmlElement(nameof(Folio))]
public long Folio { get; set; }
[XmlElement(nameof(FchEmis))]
public DateTime FchEmis { get; set; }
[XmlElement(nameof(FmaPago))]
public int FmaPago { get; set; }
[XmlElement(nameof(FchVenc))]
public DateTime FchVenc { get; set; }
}
Now we can easily create our DTE object with XmlSerializer class and its Deserialize method:
// Declaring our DTE object
var dte = (DTE)null;​
using (var reader = new StringReader(MyXML))
{
dte = (DTE)new XmlSerializer(typeof(DTE)).Deserialize(reader);
}
Now we can get Folio as property of IdDoc class, which is property of Encabezado class, which in a turn is property of Documento class. Keeping in mind possible null result turns us to use, for example, null-propagation:
var folio = dte?.Documentacion.FirstOrDefault()?.Encabezado?.IdDoc?.Folio;
As Documentacion is a List<Documento> - we use again FirstOrDefault (also may be used ElementAtOrDefault(0)) to "imitate" SelectSingleNode. And for all Folios we can use Select (also with mull-propagation):
var folios = dte?.Documentacion.Select(x => x?.Encabezado?.IdDoc?.Folio);
Sure, we can edit properties if we want or add new:
// Edit
if (dte?.Documentacion.FirstOrDefault() is Documento documento)
documento.Encabezado.IdDoc.Folio = 112233445566;
// or create and add new
var newDocumento = new Documento
{
ID = "SomeID",
Encabezado = new Encabezado
{
IdDoc = new IDDoc
{
TipoDTE = 123,
Folio = 112233445566,
FmaPago = 1,
FchEmis = DateTime.Now,
FchVenc = DateTime.Now.AddDays(1)
}
}
};
dte.Documentacion.Add(newDocumento);
And finally save back to XML file using Serialization. Here became usable our class and properties attributes (e.g. [Serializable], [XmlElement] etc), which specifies how each property should be named or represented in XML:
using (var xmlWriter = XmlWriter.Create("My.xml",
new XmlWriterSettings
{
Encoding = Encoding.GetEncoding("ISO-8859-1"),
Indent = true
}))
{
// We remove default XSI, XSD namespaces and leave only our custom:
var xmlSerializerNamespaces = new XmlSerializerNamespaces();
xmlSerializerNamespaces.Add("", "http://www.sii.cl/SiiDte");
// and saving our DTE object to XML file.
xmlSerializer.Serialize(xmlWriter, dte, xmlSerializerNamespaces);
}
Remarks
Of course, parse of XML strings could be replaces with loading XML files (by FileStreams) if needed. And of course you can edit DTE (and child) classes with other properties and mark them as XML attributes or XML elements or making collections with XmlArray and XmlArrayItem attributes - whatever, depending on your needs. Also notice about null XML nodes or its values and take care about it with, for example, Nullable<T> (e.g. long?, DateTime?), IsNullable property of XML attributes and some kind of value validation at property setter:
private long _folio;
[XmlElement(nameof(Folio), IsNullable = true)]
public long? Folio
{
get => _folio;
set => _folio = value ?? 0L; // Null-coalescing with default fallback value of 0L
}
Hope it would be helpful for your future purposes.

How to use the Serialize method from the ElasticClient class from the NEST client in c#?

I've created a successful connection to ES, and then written my json query. Now, I would like to send that query via the Serialize method.
The Serialize method requires two parameters:
1. object and
2. Stream writableStream
My question is, with the second one. When I create a stream with the following code line:
Stream wstream;
And use it to initialize my json2 variable with the following code:
var json2 = highLevelclient.Serializer.Serialize(query, wstream).Utf8String();
I get the following error on the wstream variable:
Use of unassigned local variable 'wstream'.
Am I missing something? Is it the way I create the wstream variable that is wrong? thank you.
/* \\\ edit: ///// */
There is another issue now, I use Searchblox to index and search my files, which itself calls ES 2.x to do the job. Searchblox uses a "mapping.json" file to initialize a mapping upon the creation of an index. Here's the link to that file.
As "#Russ Cam" suggested, I created my own class content with the following code (just like he did with the "questions" index and "Question" class):
public class Content
{
public string type { get; set; }
public Fields fields { get; set; }
}
public class Fields
{
public Content1 content { get; set; }
public Autocomplete autocomplete { get; set; }
}
public class Content1
{
public string type { get; set; }
public string store { get; set; }
public string index { get; set; }
public string analyzer { get; set; }
public string include_in_all { get; set; }
public string boost { get; set; }
} //got this with paste special->json class
These fields from the content class (type,store etc.) come from the mapping.json file attached above.
Now, when I (just like you showed me) execute the following code:
var searchResponse = highLevelclient.Search<Content>(s => s.Query(q => q
.Match(m => m.Field(f => f.fields.content)
.Query("service")
All I get as a response on the searchResponse variable is:
Valid NEST response built from a successful low level call on POST: /idx014/content/_search
Audit trail of this API call:
-HealthyResponse: Node: http://localhost:9200/ Took: 00:00:00.7180404
Request:
{"query":{"match":{"fields.content":{"query":"service"}}}}
Response:
{"took":1,"timed_out":false,"_shards":{"total":5,"successful":5,"failed":0},"hits":{"total":0,"max_score":null,"hits":[]}}
And no documents in searchResponse.Documents.
Contradictorily, when I search for the "service" query on Searchblox or make an API call to localhost:9200 with the Sense extension of Google Chrome, I get 2 documents. (the documents that I was looking for)
In brief, all I want is to be able to :
get all the documents (no criteria)
get all the documents within a time range and based upon keywords.. such as "service"
What am I doing wrong? I can provide with more information if needed..
Thank you all for your detailed answers.

It's actually much simpler than this with NEST :) The client will serialize your requests for you and send them to Elasticsearch, you don't need to take the step to serialize them yourself and then pass them to the client to send to Elasticsearch.
Take a search request for example. Given the following POCO
public class Question
{
public string Body { get; set; }
}
We can search for questions that contain the phrase "this should never happen" in the body with
var settings = new ConnectionSettings(new Uri("http://localhost:9200"))
.InferMappingFor<Question>(m => m
.IndexName("questions")
);
var client = new ElasticClient(settings);
var searchResponse = client.Search<Question>(s => s
.Query(q => q
.MatchPhrase(m => m
.Field(f => f.Body)
.Query("this should never happen")
)
)
);
// do something with the response
foreach (var question in searchResponse.Documents)
{
Console.WriteLine(question.Body);
}

this line
My question is, with the second one. When I create a stream with the following code line:
Stream wstream;
does not create na object. It nearly declares it. You need to new-ed it.
Stream wstream = new MemoryStream(); //doesn't have to be MemoryStream here - check what does Serialize expects
Just remember to close it later or use using statement.
using(Stream stream = new MemoryStream())
{
//do operations on wstream
} //closes automatically here

You just declared wstream but never assigned an actual stream to it. Depending on how Serialize method works it could be:
you need to create a stream and pass it to the Serialize method
or you need to pass stream parameter with out prefix

XML Element Selection

I am collecting XML data from a weather website xml file here.
I have created the following code, which finds the first instance of 'temp_c' and returns the value. This is the temperature at the current moment.
using (XmlReader reader = XmlReader.Create(new StringReader(weather)))
{
while (reader.Read())
{
switch (reader.NodeType)
{
case XmlNodeType.Element:
if (reader.Name.Equals("temp_c"))
{
reader.Read();
temp_c = reader.Value;
}
break;
}
}
}
return temp_c
This returns the value of the first instance in the XML file called "temp_c" to the string called "temp_c"
What I would now like to do is use the Element in the XML document called "period" and the element found with period called "fcttext". When "period = 0" it means "today", 1 = tomorrow, etc; and I am after the "fcttext_metric" data that is associated with that period value.
I've been struggling to work the examples and XML reading codes I've found into the current code that I have here. Can anyone please point me in the right direction?
Edit
Here is an example of the XML file:
<forecast>
<forecastday>
<period>0</period>
<fcttext_metric>Sunny</fcttext_metric>
<forecastday>
<period>1</period>
<fcttext_metric>Cloudy</fcttext_metric>

This ended up being more annoying that I originally expected, but you can create an object graph from the XML using a DataContractSerializer and a set of classes that match the XML you are reading.
First, you create your classes, with appropriate DataContract attributes.
[DataContract(Name = "response", Namespace = "")]
public class WeatherData
{
[DataMember(Name = "forecast")]
public Forecast Forecast { get; set; }
}
[DataContract(Name = "forecast", Namespace = "")]
public class Forecast
{
[DataMember(Name = "txt_forecast")]
public TxtForecast TxtForecast { get; set; }
}
[DataContract(Name = "txt_forecast", Namespace = "")]
public class TxtForecast
{
[DataMember(Name = "forecastdays")]
public ForecastDay[] ForecastDays { get; set; }
}
[DataContract(Name = "forecastday", Namespace = "")]
public class ForecastDay
{
[DataMember(Name = "period", Order = 1)]
public int Period { get; set; }
public string FctText { get; set; }
[DataMember(Name = "fcttext", EmitDefaultValue = false, Order = 5)]
private CDataWrapper FctTextWrapper
{
get { return FctText; }
set { FctText = value; }
}
}
Heres where it got complicated. The fcttext element is CDATA, which the DataContractSerializer doesn't support by default.
Using the wonderful answer available at Using CDATA with WCF REST starter kits, you create a CDataWrapper class. I won't repeat the code here (because that would be pointless), just follow the link.
You can see that I've already used the CDataWrapper class above in order to work with the fcttext element.
Once you've got the class structure setup you can use the following code to extract the information you were after. You're just navigating the object graph at this point, so you can use whatever C# you want (I've used a simple LINQ query to find Period 0 and print out the fcttext for it).
var s = new DataContractSerializer(typeof(WeatherData));
var reader = XmlReader.Create("http://api.wunderground.com/api/74e1025b64f874f6/forecast/conditions/q/zmw:00000.1.94787.xml");
var o = (WeatherData)s.ReadObject(reader);
var firstPeriod = o.Forecast.TxtForecast.ForecastDays.Where(a => a.Period == 0).Single();
Console.WriteLine(firstPeriod.FctText);
You can extend the classes as necessary to give you access to additional fields inside the XML. As long as the DataMember names match the XML fields it will all work.
Here's a short summary of some problems I ran into for anyone interested:
I had to set the Namespace attributes of all of the classes to the empty string, because the XML doesn't have any namespace info in it.
The Order attributes were important on the ForecastDay class. If they are omitted, the DataContractSerializer ends up not reading the fcttext field in at all (because it thinks fcttext should come first? not sure why to be honest).

How to extract data from JSON in ASP.NET using c#

{"pometek.net":{"status":"available","classkey":"dotnet"},"pometek.com":{"status":"available","classkey":"domcno"}}
I want to dispense this in table format. Need help.

You can use Json.NET to deserialize the json object into a C# class, and then map that class to a table format in asp.net

You shouldn't need a third-party library; the out-of-the-box JavaScriptSerializer can handle this.
class Item {
public string status { get; set; }
public string classkey { get; set; }
}
var jss = new System.Web.Script.Serialization.JavaScriptSerializer();
var input = "{\"pometek.net\":{\"status\":\"available\",\"classkey\":\"dotnet\"},\"pometek.com\":{\"status\":\"available\",\"classkey\":\"domcno\"}}";
var results = jss.Deserialize<Dictionary<string, Item>(input);
var query = results["pometek.net"].status; // = "available"
Displaying this as a table is a separate step.

Not being able to deserealize this XML

Just for some fun I was playing with the API of Last.fm. The XML file they return for top artists is structured like this:
<lfm status="ok">
<topartists user="xbonez" type="overall">
<artist rank="1">
<name>Evanescence</name>
<playcount>4618</playcount>
<mbid>f4a31f0a-51dd-4fa7-986d-3095c40c5ed9</mbid>
<url>http://www.last.fm/music/Evanescence</url>
<streamable>1</streamable>
<image size="small">http://userserve-ak.last.fm/serve/34/48488613.png</image>
<image size="medium">http://userserve-ak.last.fm/serve/64/48488613.png</image>
<image size="large">http://userserve-ak.last.fm/serve/126/48488613.png</image>
<image size="extralarge">http://userserve-ak.last.fm/serve/252/48488613.png</image>
<image size="mega">http://userserve-ak.last.fm/serve/500/48488613/Evanescence++PNG.png</image>
</artist>
</topartists>
</lfm>
This is how I'm deserealizing it.
I have a class called lfmStatus:
[Serializable()]
[XmlRootAttribute("lfm")]
public class lfmStatus
{
[XmlElement("artist")]
public List<Artists> TopArtists { get; set; }
}
And a Class Artists:
[Serializable()]
public class Artists
{
[XmlElement("name")]
public string Name { get; set; }
[XmlElement("playcount")]
public int playcount { get; set; }
[XmlElement("url")]
public string url { get; set; }
[XmlElement("streamable")]
public int streamable { get; set; }
[XmlElement("image")]
public string image { get; set; }
}
And then I deserealize using this code:
string XmlFile = "artists.xml";
XmlSerializer serializer = new XmlSerializer(typeof(lfmStatus));
lfmStatus LoadFile;
using (Stream reader = new FileStream(XmlFile, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
{
try
{
Console.WriteLine("Beginning deserialization.");
// Call the Deserialize method to restore the object's state.
LoadFile = (lfmStatus)serializer.Deserialize(reader);
return LoadFile.TopArtists;
}
Now, this code works great for the XML if it did not have the topartists tag enveloping all the artists. But since it does, how do I change my code to handle that? I'm assuming I need to add another class.

You are missing the attribute(s) on a few types.
See XmlAttributeAttribute for more detail.
You are also missing the topartists element's type.
If I was you, I would get the XML schema and just use xsd.exe to generate the C# classes, and modify from there. It can also infer the schema based on XML if you really can't find it, this will give you a parsable result based on the input XML.

To see that you wrote correct code for deserializing the response XML you can use XSD. Open VS command prompt and give XSD LastFM.xml which generates and XSD file. Now give XSD LastFM.XSD which will generate a CS file. compare that one with the one you have written and check if you made any mistakes.