SPARQL query with filtering

Question

I like to list all drugs that start with some letter to fill autocomplete text box.Here is the code

public string[] GetCompletionList(string prefixText)
{
    string rdfDat = AppDomain.CurrentDomain.BaseDirectory + "DrugRDF.rdf";

        List<string> list = new List<string>();
        TripleStore store = new TripleStore();
        Graph rdf = new Graph();
        FileLoader.Load(rdf, rdfDat, new RdfXmlParser());
        store.Add(rdf);
        string tmp = "^" + prefixText;
        string sparqlQuery = "PREFIX  mojLek: <http://www.example.org/mojLek#>"
            + "PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>"
            + "PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>"
            + "PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>"
            + "SELECT  ?x"
            + "WHERE {?h mojLek:ime ?x ."
            + "FILTER regex(str(?x),"+tmp+")            }";


        SparqlQueryParser sparqlParser = new SparqlQueryParser();
        SparqlQuery query = sparqlParser.ParseFromString(sparqlQuery);
        Object results = store.ExecuteQuery(query);
        if (results is SparqlResultSet)
        {
            SparqlResultSet r = results as SparqlResultSet;

            foreach (SparqlResult res in r)
            {

                list.Add(res["x"].ToString().ToLower());
            }
        }

        return list.ToArray();


}

However if I try it with for example A there are already couples that starts with A I got this error

VDS.RDF.Parsing.RdfParseException: [Line 1 Column 263] The value 'A' is not valid as a QName


at VDS.RDF.Parsing.Tokens.SparqlTokeniser.TryGetQNameOrKeyword()

at VDS.RDF.Parsing.Tokens.SparqlTokeniser.GetNextToken() at VDS.RDF.Parsing.Tokens.TokenQueue.InitialiseBuffer() at VDS.RDF.Parsing.SparqlQueryParser.ParseInternal(SparqlQueryParserContext context) at VDS.RDF.Parsing.SparqlQueryParser.ParseInternal(TextReader input) at VDS.RDF.Parsing.SparqlQueryParser.ParseFromString(String queryString) at SuggestWebService.GetCompletionList(String prefixText) in d:\Suggest\App_Code\SuggestWebService.cs:line 57

Answer 1

Put newlines in the query string to make the error messages better.

There are no SPARQL quotes at

regex(str(?x),"+tmp+")

Try:

regex(str(?x),'"+tmp+"')

which puts single quotes into the SPARQL. Be careful of any quotes in tmp.

Answer 2

I have changed my code in this way so it worked for me

        string tmp="^"+prefixText;
        var query = "PREFIX  mojLek: <http://www.example.org/mojLek#>"
            + "PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>"
            + "PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>"
            + "PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>"
            + "PREFIX fn: <http://www.w3.org/2005/xpath-functions#>"
            + "SELECT  ?x ?h"
            + "WHERE {?h mojLek:ime ?x ."
            + "FILTER regex(?x,\""+tmp+"\")"
                +"}";