kuzu - improve type inference for connection

cognee/infrastructure/databases/graph/kuzu/adapter.py

@@ -145,6 +145,12 @@ class KuzuAdapter(GraphDBInterface):
         except Exception as e:
             logger.error(f"Failed to initialize Kuzu database: {e}")
             raise e
+    
+    def _get_connection(self) -> Connection:
+        """Get the connection to the Kuzu database."""
+        if not self.connection:
+            raise RuntimeError("Kuzu database connection not initialized")
+        return self.connection
 
     async def push_to_s3(self) -> None:
         if os.getenv("STORAGE_BACKEND", "").lower() == "s3" and hasattr(self, "temp_graph_file"):
@@ -152,9 +158,9 @@ class KuzuAdapter(GraphDBInterface):
 
             s3_file_storage = S3FileStorage("")
 
-            if self.connection:
+            if self._get_connection():
                 async with self.KUZU_ASYNC_LOCK:
-                    self.connection.execute("CHECKPOINT;")
+                    self._get_connection().execute("CHECKPOINT;")
 
             s3_file_storage.s3.put(self.temp_graph_file, self.db_path, recursive=True)
 
@@ -192,14 +198,14 @@ class KuzuAdapter(GraphDBInterface):
 
         def blocking_query() -> List[Tuple[Any, ...]]:
             try:
-                if not self.connection:
+                if not self._get_connection():
                     logger.debug("Reconnecting to Kuzu database...")
                     self._initialize_connection()
 
-                if not self.connection:
+                if not self._get_connection():
                     raise RuntimeError("Failed to establish database connection")
 
-                result = self.connection.execute(query, params)
+                result = self._get_connection().execute(query, params)
                 rows = []
 
                 if not isinstance(result, list):
@@ -233,7 +239,7 @@ class KuzuAdapter(GraphDBInterface):
         and on exit performs cleanup if necessary.
         """
         try:
-            yield self.connection
+            yield self._get_connection()
         finally:
             pass
 
@@ -1517,8 +1523,8 @@ class KuzuAdapter(GraphDBInterface):
         It raises exceptions for failures occurring during deletion processes.
         """
         try:
-            if self.connection:
-                self.connection.close()
+            if self._get_connection():
+                self._get_connection().close()
                 self.connection = None
             if self.db:
                 self.db.close()
@@ -1549,7 +1555,7 @@ class KuzuAdapter(GraphDBInterface):
         occur during file deletions or initializations carefully.
         """
         try:
-            if self.connection:
+            if self._get_connection():
                 self.connection = None
             if self.db:
                 self.db.close()
@@ -1566,20 +1572,23 @@ class KuzuAdapter(GraphDBInterface):
             # Reinitialize the database
             self._initialize_connection()
             
-            if not self.connection:
+            if not self._get_connection():
                 raise RuntimeError("Failed to establish database connection")
                 
             # Verify the database is empty
-            result = self.connection.execute("MATCH (n:Node) RETURN COUNT(n)")
+            result = self._get_connection().execute("MATCH (n:Node) RETURN COUNT(n)")
             if not isinstance(result, list):
                 result = [result]
             for single_result in result:
-                count = single_result.get_next()[0] if single_result.has_next() else 0 # type: ignore
+                _next = single_result.get_next()
+                if not isinstance(_next, list):
+                    raise RuntimeError("Expected list of results")
+                count = _next[0] if _next else 0
             if count > 0:
                 logger.warning(
                     f"Database still contains {count} nodes after clearing, forcing deletion"
                 )
-                self.connection.execute("MATCH (n:Node) DETACH DELETE n")
+                self._get_connection().execute("MATCH (n:Node) DETACH DELETE n")
             logger.info("Database cleared successfully")
         except Exception as e:
             logger.error(f"Error during database clearing: {e}")