Extracting data from a complex XML with LINQ

Question

My goal is to save the data contained in the ValueReference node, TimeInstant attribute, and timePosition node into variables. I am able to get the value of the valueReference node (the un-commented section works), but not the other two. Any help would be greatly appreciated.

Here is the code that I am working on:

public void LinqToXml()
{
    XNamespace sosNamespace = XNamespace.Get("http://www.opengis.net/sos/2.0");
    XNamespace fesNamespace = XNamespace.Get("http://www.opengis.net/fes/2.0");
    XNamespace gmlNamespace = XNamespace.Get("http://www.opengis.net/gml/2.0");
    var root = XElement.Load(@"C:\Working Directory\OGCSOS.Service\OGCSOS.Service\Resources\GetObservation_TemporalFilter.xml");
    var a = (from level in root.Descendants(sosNamespace + "temporalFilter")
             select new
             {
                 valueReference = (string)level.Descendants(fesNamespace + "After")
                                               .Elements(fesNamespace + "ValueReference")
                                               .First(),
                 /*timeInstant = (string)level.Descendants(fesNamespace + "After")
                                               .Elements(gmlNamespace + "TimeInstant")
                                               .Attributes(gmlNamespace + "id")
                                               .First()*/
                 /*timePosition = (string)level.Descendants(fesNamespace + "After")
                                             .Elements(gmlNamespace + "TimeInstant")
                                             .First()*/
             }).ToList();

And here is the XML I am trying to read:

    <?xml version="1.0" encoding="UTF-8"?>
<sos:GetObservation xmlns="http://www.opengis.net/sos/2.0" service="SOS" version="2.0.0" 
                    xmlns:sos="http://www.opengis.net/sos/2.0" xmlns:fes="http://www.opengis.net/fes/2.0" 
                    xmlns:gml="http://www.opengis.net/gml/3.2" xmlns:swe="http://www.opengis.net/swe/2.0" 
                    xmlns:swes="http://www.opengis.net/swes/2.0" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.opengis.net/sos/2.0
http://schemas.opengis.net/sos/2.0/sos.xsd">

    <!--identifier of an offering-->
    <offering>HG.Logger@DJK001</offering>

    <!--identifier of an observed property-->
    <observedProperty>HG</observedProperty>

    <!--optional temporal filter restricting the results which shall be returned-->
    <temporalFilter>
        <fes:After>
            <fes:ValueReference>phenomenonTime</fes:ValueReference>
            <gml:TimeInstant gml:id="startPosition">
                <gml:timePosition>2008-03-01T17:44:15.000+00:00</gml:timePosition>
            </gml:TimeInstant>
        </fes:After>
    </temporalFilter>

    <featureOfInterest>DJK001</featureOfInterest>

</sos:GetObservation>

Also, if somebody can suggest an alternative approach that might be easier I am all ears. — Jollyra
– Jollyra, Commented Oct 25, 2012 at 16:40
Well XNamespace sosNamespace = XNamespace.Get("http://www.opengis.net/sos/2.0"); can be shortened to XNamespace sosNamespace = "http://www.opengis.net/sos/2.0";. And as the idea behind the XNamespace class is to use instances to construct XNames by concatenation I would use a short variable name instead e.g. XNamespace sos = "http://www.opengis.net/sos/2.0";, then when calling axis methods you have shorter expressions e.g. foo.Elements(sos + "Bar"). — Martin Honnen
– Martin Honnen, Commented Oct 25, 2012 at 16:54
@MartinHonnen Thanks for the suggestions, I'll make the changes. — Jollyra
– Jollyra, Commented Oct 25, 2012 at 17:06

L.B · Accepted Answer · 2012-10-25 16:53:33Z

2

Your gml namespace is not correct, after changing it to

 XNamespace gmlNamespace = XNamespace.Get("http://www.opengis.net/gml/3.2");

you can use

timeInstant = level.Descendants(fesNamespace + "After")
                   .First()
                   .Element(gmlNamespace + "TimeInstant")
                   .Attribute(gmlNamespace + "id")
                   .Value,

timePosition = level.Descendants(fesNamespace + "After")
                    .First()
                    .Element(gmlNamespace + "TimeInstant")
                    .Value

answered Oct 25, 2012 at 16:53

L.B

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Comments

Anirudha · Accepted Answer · 2012-10-25 17:11:55Z

1

You should do it like this

XNamespace sosNamespace = "http://www.opengis.net/sos/2.0";
XNamespace fesNamespace = "http://www.opengis.net/fes/2.0";
XNamespace gmlNamespace = "http://www.opengis.net/gml/3.2";
//you had used 2.0 instead of 3.2
var root = XElement.Load(@"C:\WorkingDirectory\OGCSOS.Service\OGCSOS.Service\Resources\GetObservation_TemporalFilter.xml");
var yourList=root.Descendants(sosNamespace+"temporalFilter").Descendants(fesNamespace+"After").Select(x=>
new
{
ValueReference=x.Element(fesNamespace+"ValueReference").Value,
timeInstant=x.Element(gmlNamespace+"TimeInstant").Attribute(gmlNamespace+"id").Value,
timePosition=x.Element(gmlNamespace+"TimeInstant").Element(gmlNamespace+"timePosition").Value
}
);

yourList contains all the data

edited Oct 25, 2012 at 17:11

answered Oct 25, 2012 at 16:49

Anirudha

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Comments

roman · Accepted Answer · 2012-10-25 17:41:33Z

1

you can also use good old XPath

    var doc = new XPathDocument("1.xml");
    var nav = doc.CreateNavigator();
    var mng = new XmlNamespaceManager(nav.NameTable);
    mng.AddNamespace("sos", "http://www.opengis.net/sos/2.0");
    mng.AddNamespace("fes", "http://www.opengis.net/fes/2.0");
    mng.AddNamespace("gml", "http://www.opengis.net/gml/3.2");
    var valueReference = nav.SelectSingleNode("//sos:GetObservation/sos:temporalFilter/fes:After/fes:ValueReference[1]", mng).TypedValue;
    var TimeInstant = nav.SelectSingleNode("//sos:GetObservation/sos:temporalFilter/fes:After/gml:TimeInstant/@gml:id", mng).TypedValue;
    var timePosition = nav.SelectSingleNode("//sos:GetObservation/sos:temporalFilter/fes:After/gml:TimeInstant/gml:timePosition[1]", mng).TypedValue;

answered Oct 25, 2012 at 17:41

roman

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1 Comment

Jollyra Over a year ago

I did also give this a shot, but figured I was too deep into learning LINQ to continue. Thanks for the good example.

Rahul Ranjan · Accepted Answer · 2012-10-25 17:05:23Z

TRY THIS CODE:

XmlDocument xmlSnippet = new XmlDocument();
 xmlSnippet.Load(@"C:\Working Directory\OGCSOS.Service\OGCSOS.Service\Resources\GetObservation_TemporalFilter.xml");

 //Selects all the similar nodes by tag Name.......
               XmlNodeList xmlSnippetNodes = xmlSnippet.GetElementsByTagName("fes:After");

 //Checking if any any xmlSnippetNode has matched.
               if (xmlSnippetNodes != null)
               {
                   //Checks if the matched xmlSnippetNode that has fes:After attribute is not  NULL


//Stores the value of the matched tag.
                          var valueReference= xmlSnippetNodes.Item(0).Value;

                   var timeInstance=xmlSnippetNodes.Item(1).Attributes["gml:id"].Value;
                 var timePosition =xmlSnippetNodes.Item(1).InnerXml.Name;


                           //Return True if updated correctly.
                           isUpdated = true;


                   }

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