[redland-dev] processing results

[Jagdev Bhogal]

Hello 

I have got the following code which reads the news.rdf file and outputs
the results of the query (basically all 84 records) to a queryoutput
file.

However the code only seems to go around the while loop once, when I
expect it go around 84 times.

When I am debugging it I use a counter called qocount to tell me how
many times the code goes around the while loop.

What I need to do is process the variables and bindings in record 1 ,
then record 2 etc until all records in the result have been processed.

I am obviously missing something, I  hope you can help me out on this.

Thanks

 

main()

{

  int i, qocount;

  rasqal_query *rq;

  rasqal_query_results *results;

  const unsigned char *value_string;

  const char *outcome;

  char keyword[]="Content:Abstract";

  raptor_iostream *qo;

  const char  *query_string="select ?label, ?comment from
<file:/export/CISR-D/jagdev/okapi/progs/news.rdf> where (?x rdf:type
rdfs:Class) (?x,rdfs:label, ?label), (?x, rdfs:comment, ?comment)  using
rdf for <http://www.w3.org/1999/02/22-rdf-syntax-ns#>, rdfs for
<http://www.w3.org/2000/01/rdf-schema#>";

const char *qfilename="queryoutput";

rasqal_init();

rq=rasqal_new_query("rdql",NULL);

raptor_init();

qo=raptor_new_iostream_to_filename(qfilename);

rasqal_query_prepare(rq,query_string, NULL);

results=rasqal_query_execute(rq);

qocount=0;

while(!rasqal_query_results_finished(results)) {

 
for(i=0;i<rasqal_query_results_get_bindings_count(results);i++) {

                const char
*name=rasqal_query_results_get_binding_name(results,i);

                rasqal_literal *value;

                value=rasqal_query_results_get_binding_value(results,i);

                rasqal_literal_print(value, stderr);

                value_string=rasqal_literal_as_string(value);

                if (strcmp(value_string,keyword) == 0)
fprintf(stderr,"Match found \n");

fprintf(stderr,"writing line %d in queryoutput file \n",qocount);

qocount++;

rasqal_query_results_write(qo,results,NULL,NULL);

        }

        fprintf(stderr,"results count is
%d\n",rasqal_query_results_get_count(results));

        rasqal_query_results_next(results);

        }

raptor_free_iostream(qo);

rasqal_free_query_results(results);

rasqal_free_query(rq);

  rasqal_finish();

raptor_finish();

}

 

Many thanks

 

Mrs Jagdev Bhogal

Senior Lecturer in Database Systems

Dept. of Computing

University of Central England

Feeney Building

Perry Barr

Birmingham

B42 2SU

Tel: 0121 331 7658

 

 

 

Mrs Jagdev Bhogal

Senior Lecturer in Database Systems

Dept. of Computing

University of Central England

Feeney Building

Perry Barr

Birmingham

B42 2SU

Tel: 0121 331 7658

 

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