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c#sparqldotnetrdfallegrograph

Querying AllegroGraph using dotNetRDF

I've got a AllegroGraph server running and have trouble querying remote datastore, there's very little information on documentation.

Here's my lil piece of code:

using System;
using VDS.RDF;
using VDS.RDF.Storage;

namespace PoC {
  class Program {
    static void Main(string[] args) {
      string server = "http://server";
      string repo = "repo";
      string username = "username";
      string password = "password";

      AllegroGraphConnector agraph = new AllegroGraphConnector(server, repo, username, password);

      Options.HttpDebugging = true;
      Options.HttpFullDebugging = true;

      agraph.Query("SELECT * WHERE { emid:_PCAT_0001 ?p ?o }");
      Console.ReadLine();
    }
  }
}

MALFORMED QUERY: Parse error: namespace mapping for "emid" not defined when expanding QName "emid:_PCAT_0001".

Although in AllegroGraph WebView I can run exactly the same query and namespace is loaded into repository.

How do I resolve that?

Solution

  • You will need to declare the prefix emid: in your query. Presumably the AllegroGraph WebView UI is doing that automatically for you, but the plain SPARQL endpoint won't.

    Try using something like this:

    agraph.Query("PREFIX emid: <http://your.uri.goes/here> SELECT * WHERE { emid:_PCAT_0001 ?p ?o }");

    Obviously you should replace that fake URI with the real URI that your emid: prefix maps to!