Re: [dotNetRDF-Support] NamespaceMap on parsetime

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

Hi Jens

There is no way to add a Namespace to the parser, it must be defined in the 
query but you can do this without lots of nasty string concatenation by 
using the SparqlParameterizedString class.  Essentially this has a 
Namespaces property that can be used to build a namespace map and 
automatically inserts the appropriate prefix declarations into the 
querystring when it is passed to the parser.

SparqlParameterizedString queryString = new SparqlParameterizedString();

 //Define as many namespaces as you want - note that the Namespace Map for 
a Parameterized

//String will be empty by default so you typically need to define rdf 
namespace as well 
queryString.Namespaces.AddNamespace("rdf", new 
Uri(RdfSpecsHelper.RdfType));
queryString.Namespaces.AddNamespace("foaf", new 
Uri("http://xmlns.com/foaf/0.1/"));

//Use CommandText to set the actual query text
queryString.CommandText = "SELECT ?image WHERE 
{?image rdf:type foaf:Image}";

//Then parse the query from a string as usual
SparqlQueryParser parser = new SparqlQueryParser();
SparqlQuery query = parser.ParseFromString(queryString);

//Finally go ahead and process the query however you wish 

Hope this helps, if you have any further questions please let me know

Regards,

Rob Vesse

----------------------------------------
From: "Jens Panneel" <jen...@gm...>
Sent: 10 May 2011 10:52
To: dot...@li...
Subject: SPAM-LOW:  [dotNetRDF-Support] NamespaceMap on parsetime 



Hi
 
I am doing the folowing: 
 
http://pastebin.com/rfTC0fZu
 
/* 
* Getting an error from ParseFromString, saying:
* The Namespace URI for the given Prefix 'foaf' is not known by the 
in-scope NamespaceMapper
* 
* My question how can i add a Namespace before the parsing?
* I don't like the idea of manualy concatenating a lot of prefix strings to 

build my queries. 
*
*/ 
 
ISparqlQueryProcessor processor = new RemoteQueryProcessor(new 
SparqlRemoteEndpoint(new Uri("http://localhost:11025/sparql/query")));
SparqlQueryParser sparqlparser = new SparqlQueryParser();
SparqlQuery query = sparqlparser.ParseFromString("SELECT ?image WHERE 
{?image rdf:type foaf:Image}");
query.NamespaceMap.AddNamespace("foaf", new 
Uri("http://xmlns.com/foaf/0.1/"));
Object results = processor.ProcessQuery(query);
 
So is there a way to add a namespace to the parser?
 
Thanks 
 
JPanneel