Re: [dotNetRDF-Support] how can i use SPARQL to query local OWL/RDF file by using dotNetRdf library ?

[Rob V. <rv...@vd...>]

        Hi Anji


        You must explicitly define any prefixes that you want to use in 
your
        queries.


        So your query should look like the following:


        Object results = g.ExecuteQuery("PREFIX rdfs:
        <http://www.w3.org/2000/01/rdf-schema#> PREFIX owl:
        <http://www.w3.org/2002/07/owl#> SELECT * WHERE { ?Bonds
        rdfs:subClassOf owl:class} ");


        Hope this helps,


        Rob


        On 4/11/12 2:10 AM, anji reddy wrote:


        Hi,

               I am getting an error while querying .owl file from my
        application......

        The error code : The Namespace URI for the given Prefix 'owl' is
        not known by the in-scope NamespaceMapper

        in the line ---------- Object results = g.ExecuteQuery("SELECT *
        WHERE { ?Bonds rdfs:subClassOf owl:class} ");


        Here, I am attaching my .owl file (developed by using protege
        tool) and the below application code. 

        i want read synonyms of Bonds from my owl file..... pls help
        me... i am not getting much more from it....


         

        Sample Code:


        using System;

        using System.Collections.Generic;

        using System.Linq;

        using System.Web;

        using System.Web.UI;

        using System.Web.UI.WebControls;

        using VDS.RDF;

        using VDS.RDF.Query;

        using VDS.RDF.Parsing;

        using VDS.RDF.Web;


        namespace SPARQL

        {

            public partial class _Default : System.Web.UI.Page

            {

                protected void Page_Load(object sender, EventArgs e)

                {

                     //Define your Graph here - it may be better to use
        a QueryableGraph if you plan

                    //on making lots of Queries against this Graph as
        that is marginally more performant


                    IGraph g = new Graph();


                    //Load some data into your Graph using the
        LoadFromFile() extension method

                   
        
g.LoadFromFile(@"C:\Users\admin\Desktop\UDDI\SPARQL\SPARQL\FinancialInvestme
nt.owl");


                    //Use the extension method ExecuteQuery() to make
        the query against the Graph

                    try

                    {

                        Object results = g.ExecuteQuery("SELECT * WHERE
        { ?Bonds rdfs:subClassOf owl:class} ");


                     }

                        if (results is SparqlResultSet)

                        {

                            //SELECT/ASK queries give a
        SparqlResultSet

                            SparqlResultSet rset =
        (SparqlResultSet)results;

                            foreach (SparqlResult r in rset)

                            {

                                //Do whatever you want with each
        Result

                            }

                        }

                        else if (results is IGraph)

                        {

                            //CONSTRUCT/DESCRIBE queries give a
        IGraph

                            IGraph resGraph = (IGraph)results;

                            foreach (Triple t in resGraph.Triples)

                            {

                                //Do whatever you want with each
        Triple

                            }

                        }

                        else

                        {

                            //If you don't get a SparqlResutlSet or
        IGraph something went wrong 

                            //but didn't throw an exception so you
        should handle it here

                            Console.WriteLine("ERROR");

                        }

                    }

                    catch (RdfQueryException queryEx)

                    {

                        //There was an error executing the query so
        handle it here

                        Console.WriteLine(queryEx.Message);

                    }


                }

            }

        }


        
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