Sparql GROUP_CONCAT returns empty json tag for empty results.

[akshay.des...@gmail.com]

Hi,

I have the below sparql query

select distinct ?isbn ?bookTitle ?subTitle ?seriesTitle ?seriesSubCategory ?copyrightYear (GROUP_CONCAT(?editorName; SEPARATOR = ",") AS ?editorNames) where
{


{
  select distinct ?pointer where {
  ?bookProfile a smt:BookProfile.
  ?pointer smt:compiledIn ?bookProfile;
       smt:searchLabel ?searchLabel.
   filter regex (?searchLabel, "[.]*benzene[.]*", "i")
  }
  offset 0
  limit 20
}


 ?pointer smt:electronicISBN ?isbn;
       smt:title ?bookTitle;
       smt:subTitle ?subTitle;
       smt:seriesTitle ?seriesTitle;
       smt:seriesSubCategory ?seriesSubCategory;
       smt:copyrightHolderName ?copyrightHolderName;
       smt:copyrightYear ?copyrightYear;
       smt:editor ?editor.


 ?editor smt:name ?editorName.




}
group by ?isbn ?bookTitle ?subTitle ?seriesTitle ?seriesSubCategory ?copyrightYear ?editorNames

and below is the resulting json from this query 

{
 "head" : {
   "vars" : [
     "isbn",
     "bookTitle",
     "subTitle",
     "seriesTitle",
     "seriesSubCategory",
     "copyrightYear",
     "editorNames"
   ]
 },
 "results" : {
   "bindings" : [
     {
       "editorNames" : {
         "type" : "literal",
         "value" : ""
       }
     }
   ]
 }
}

I don't want the empty json tag if the result is empty.

How can i handle this at the query level ?

Thanks,

Akshay

[Evren Sirin]

You can add a filter at the end to eliminate such results:

HAVING (?editorNames) != "")

Best,
Evren

> --
> -- --
> You received this message because you are subscribed to the C&P "Stardog"
> group.
> To post to this group, send email to sta...@clarkparsia.com
> To unsubscribe from this group, send email to
> stardog+u...@clarkparsia.com
> For more options, visit this group at
> http://groups.google.com/a/clarkparsia.com/group/stardog?hl=en