Fix JSON syntax errors

- Missing braces level
- Add escape function for JSON strings (beware of the backslashes)

tetras_extraction/macao_12/result/activities/MosMod95/MosMod60/MosEtp746/pg228/quiz.json

 {
   "elements": [
+    {
       
+    }
   ]
 }

tetras_extraction/macao_12/result/activities/MosMod95/MosMod60/MosEtp746/pg293/quiz.json

 {
   "elements": [
+    {
       
+    }
   ]
 }

tetras_extraction/macao_12/result/activities/MosMod95/MosMod60/MosEtp746/pg313/quiz.json

 {
   "elements": [
-    "name": "pg313",
-    "type": "radiogroup",
-    "choices": [
-      "<div class="STY_reponseQC" id="lienRep1"",
-      "<div class="STY_reponseQC" id="lienRep2"",
-      "<div class="STY_reponseQC" id="lienRep3"",
-      "<div class="STY_reponseQC" id="lienRep4""
-    ],
-    "correctAnswer": ""
+    {
+      
+    }
   ]
 }

tetras_extraction/macao_12/result/activities/MosMod95/MosMod60/MosEtp746/pg400/quiz.json

 {
   "elements": [
-    "name": "pg400",
-    "type": "radiogroup",
-    "choices": [
-      "<div class="STY_reponseQC" id="lienRep1"",
-      "<div class="STY_reponseQC" id="lienRep2"",
-      "<div class="STY_reponseQC" id="lienRep3"",
-      "<div class="STY_reponseQC" id="lienRep4""
-    ],
-    "correctAnswer": ""
+    {
+      
+    }
   ]
 }

tetras_extraction/macao_12/result/activities/MosMod95/MosMod60/MosEtp746/pg436/quiz.json

 {
   "elements": [
+    {
       
+    }
   ]
 }

tetras_extraction/macao_12/result/activities/MosMod95/MosMod60/MosEtp746/pg449/quiz.json

 {
   "elements": [
+    {
       
+    }
   ]
 }

tetras_extraction/macao_12/result/activities/MosMod95/MosMod60/MosEtp746/pg6121/quiz.json

 {
   "elements": [
+    {
       
+    }
   ]
 }

tetras_extraction/macao_12/result/activities/MosMod95/MosMod60/MosEtp746/pg665/quiz.json

 {
   "elements": [
+    {
       
+    }
   ]
 }

tetras_extraction/macao_12/result/activities/MosMod95/MosMod60/MosEtp746/pg6811/quiz.json

 {
   "elements": [
+    {
       
+    }
   ]
 }

tetras_extraction/macao_12/result/activities/MosMod95/MosMod60/MosEtp746/pg71/quiz.json

 {
   "elements": [
+    {
       
+    }
   ]
 }

tetras_extraction/macao_12/result/activities/MosMod95/MosMod60/MosEtp746/pg740/quiz.json

 {
   "elements": [
+    {
       
+    }
   ]
 }

tetras_extraction/macao_12/result/activities/MosMod95/MosMod60/MosEtp746/pg8412/quiz.json

 {
   "elements": [
+    {
       
+    }
   ]
 }

tetras_extraction/macao_12/result/activities/MosMod95/MosMod60/MosEtp746/pg966/quiz.json

 {
   "elements": [
-    "name": "pg966",
-    "type": "radiogroup",
-    "choices": [
-      "<div class="STY_reponseQC" id="lienRep1"",
-      "<div class="STY_reponseQC" id="lienRep2"",
-      "<div class="STY_reponseQC" id="lienRep3"",
-      "<div class="STY_reponseQC" id="lienRep4""
-    ],
-    "correctAnswer": ""
+    {
+      
+    }
   ]
 }

tetras_extraction/macao_12/script/src/export_corese.py

@@ -45,4 +45,5 @@ def apply_templates() -> str:
 
     # ==> Run STTL transformation
     tr = Transformer.create(graph, MODULE_DIR + "/../templates/")
-    return tr.transform()
+    result = tr.transform()
+    return result

tetras_extraction/macao_12/script/templates/functions.rq

@@ -27,3 +27,40 @@ function st:process(?x) {
 function mt:sep() {
     st:format(",%s", st:nl())
 }
+
+# Escape illegal characters for JSON strings
+function mt:json_escape(?str) {
+    # Welcome to Backslash Hell! Buckle up mate, you're in for a ride...
+    # - The SPARQL syntax for string literals understands backslash escapes,
+    #   which means '\n' is a newline character and '\\' is a literal backslash.
+    # - The replace() function takes a SPARQL/XPath regex as second argument,
+    #   and the regex engine *also* understands backslash escapes, which means
+    #   that if you want to replace an actual backslash, you need two in the 
+    #   regex, i.e. four in the string literal. For control characters like
+    #   the newline, you need '\\n' (actual backslash + letter n)
+    # - The replacement string (3rd argument) is not a regex, but to replace the
+    #   value of a capturing group, it uses the '$1' notation... which, you
+    #   guessed it, can be escaped, therefore actual backslashes must be escaped
+    #   just like in the regex.
+    # - We want to print a backslash as part of the replacement value (like
+    #   '\n' which is valid JSON), so we have to escape it twice, i.e. 4 times
+    #   in the string literal (or 8 times if we want to print two of them).
+    # - Finally, for some weird reason, '\b' (Backspace) is an exception and
+    #   breaks the regex engine (deletes a character inside?) but is fine when
+    #   unescaped.
+    replace(
+        replace(
+            replace(
+                replace(
+                    replace(
+                        replace(
+                            replace(
+                                ?str,'\\\\', '\\\\\\\\'
+                            ), '\b', '\\\\b'
+                        ), '\\f', '\\\\f'
+                    ), '\\n', '\\\\n'
+                ), '\\r', '\\\\r'
+            ), '\\t', '\\\\t'
+        ), '"', '\\\\"'
+    )
+}
\ No newline at end of file

tetras_extraction/macao_12/script/templates/qcu.rq

@@ -13,12 +13,12 @@ template mt:qcu(?qcu) {
         # while the rest of the template is only instantiated once.
         # This is similar to a SQL 'GROUP BY every variable except these'
         group {
-            '"' ?choice_html '"'
+            '"' mt:json_escape(?choice_html) '"'
             ; separator=mt:sep()
         }
     }
     ']' mt:sep()
-    '"correctAnswer": "' ?correct_choice_html '"'
+    '"correctAnswer": "' mt:json_escape(?correct_choice_html) '"'
 }
 where {
     ?qcu a :ExerciceQC_QCU

tetras_extraction/macao_12/script/templates/quiz.rq

@@ -7,9 +7,13 @@ template mt:quiz(?quiz) {
     '{'
     box {
         '"elements": ['
+        box {
+            "{"
             box {
                 st:call-template(mt:qcu, ?quiz) 
             }
+            "}"
+        }
         ']'
     }
     '}'