Replace prefixed names with URIs in SPARQL Query which has no Prefixes

Question

I get a SPARQL query string from a service which looks like the following query:

SELECT * FROM { ?s owl:sameAs ?p } 

If I try to parse this with the QueryFactory class I get the Unresolved Prefixed Name Exception which totally makes sense.

I have a properties file which maps the predefined namespace prefixes .

For now I have a workaround which looks like the following:

Iterator<String> it = prefixConfig.getKeys();
String prefixes = "";
while(it.hasNext()) {
    String p = it.next();
    prefixes += "PREFIX " + p + ":<" + prefixConfig.getString(p) + "> ";
}

Query q = QueryFactory.create(prefixes + query);
it = prefixConfig.getKeys();
while(it.hasNext()) {
    String p = it.next();
    q.getPrefixMapping().removeNsPrefix(p);
}

query = q.toString();

This works but I am not happy at all with this solution , so my question is:

Is there a good way to either replace the prefixes in the SPARQL query string or to only add the relevant prefixes?

Thanks a lot in advance!

Answer 1

public static String replacePrefixes(String query, PrefixMapping pmap){
    /* With Prologue and the parse method, 
     * the queryString gets parsed without an error
     */
    Prologue prog = new Prologue();
    prog.setPrefixMapping(pmap);
    Query q = QueryFactory.parse(new Query(prog), query, null, null);
    //Set Prefix Mapping
    q.setPrefixMapping(pmap);
    //remove PrefixMapping so the prefixes will get replaced by the full uris
    q.setPrefixMapping(null);       
    return q.serialize();
}

This works for me :)