Linq to XML

Con linq è semplice interrogare un element: in questo esempio ho copiato una parte di file GML.

XElement gml = XElement.Parse(

        @"<features><feature fid=""142"" featuretype=""school"" description=""A middle school"">

        <polygon name=""extent"" srsname=""epsg:27354"">

        <linestring name=""extent"" srsname=""epsg:27354"">

        <cdata>

        491888.999999459,5458045.99963358 491904.999999458,5458044.99963358

        491908.999999462,5458064.99963358 491924.999999461,5458064.99963358

        491925.999999462,5458079.99963359 491977.999999466,5458120.9996336

        491953.999999466,5458017.99963357 </cdata>

        </linestring>

        </polygon>

        </feature><feature fid=""143"" featuretype=""house"" description=""a house"">

        <polygon name=""extent"" srsname=""epsg:27354"">

        <linestring name=""extent"" srsname=""epsg:27354"">

        <cdata>

        491888.999999459,5458045.99963358 491904.999999458,5458044.99963358

        491908.999999462,5458064.99963358 491924.999999461,5458064.99963358

        491925.999999462,5458079.99963359 491977.999999466,5458120.9996336

        491953.999999466,5458017.99963357 </cdata>

        </linestring>

        </polygon>

        </feature></features>");

 

 

        //Seleziono la feature con fid = 143

 

        var query = from p in gml.Elements("feature") where (int)p.Attribute("fid") == 143 select p;

 

        //visualizzo i suoi attributi

        foreach (var rec in query)

            Console.WriteLine("Feature: type:{0} - description: {1}", rec.Attribute("featureType").Value, rec.Attribute("Description").Value);