generate json with surveyjs_json in ttl

tetras_extraction/script/templates/activite.rq

@@ -18,6 +18,7 @@ template mt:activite(?act) {
     # Insert a Hugo shortcode to load the quiz if this is a quiz activity
     if (exists { ?act a :Exercice }, "\n{{< quiz >}}", "")
     st:call-template(mt:quiz, ?act)
+    st:call-template(mt:json_in_ttl, ?act)
 }
 where {
     ?act a :Activite .

tetras_extraction/script/templates/json_in_ttl.rq

@@ -4,7 +4,10 @@ PREFIX st: <http://ns.inria.fr/sparql-template/>
 
 # Template for the JSON definition of QCU activities
 template mt:json_in_ttl(?quiz) {
+    st:nl()
+    mt:start_marker(?quiz) "/quiz.json" st:nl()
     ?json
+    st:nl()
 }
 where {
     ?quiz :surveyjs_json ?json

tetras_extraction/script/templates/quiz.rq

@@ -45,6 +45,7 @@ where {
     optional {
         ?quiz :commentaireSugg_md ?incorrect_comment .
     }
+    FILTER(NOT EXISTS{?quiz :surveyjs_json ?json})
 }
 # FIXME: some exercises have multiple incorrect comments, almost identical,
 # which creates multiple matches for the WHERE clause and thus duplicate files.