anpassung der string rep von Source ID um none zu vermeiden

math-tutor/backend/app/deterministic_services/vector_store.py

@@ -273,11 +273,18 @@ class SourceID:
     chapter_title: Optional[str]
     section_title: Optional[str]
     subsection_title: Optional[str]
-    title: Optional[str]
+    title: str
     doc_type: str
 
     def to_string(self) -> str:
-        return f"[{self.chapter_title}|{self.section_title}|{self.subsection_title}|{self.title}|{self.doc_type}]"
+        string_rep = self.title
+        if self.subsection_title:
+            string_rep = f"{self.subsection_title}|{string_rep}"
+        if self.section_title:
+            string_rep = f"{self.section_title}|{string_rep}"
+        if self.chapter_title:
+            string_rep = f"{self.chapter_title}|{string_rep}"
+        return f"[{string_rep}|{self.doc_type}]"
 
 
 def _row_to_retrieved(row: Dict[str, Any]) -> Retrieved: