add type annotation to DB utils

As a cursor is needed as type, make this a public type.

nominatim/db/connection.py

@@ -22,7 +22,7 @@ from nominatim.errors import UsageError
 
 LOG = logging.getLogger()
 
-class _Cursor(psycopg2.extras.DictCursor):
+class Cursor(psycopg2.extras.DictCursor):
     """ A cursor returning dict-like objects and providing specialised
         execution functions.
     """
@@ -82,18 +82,18 @@ class Connection(psycopg2.extensions.connection):
         adds convenience functions for administrating the database.
     """
     @overload # type: ignore[override]
-    def cursor(self) -> _Cursor:
+    def cursor(self) -> Cursor:
         ...
 
     @overload
-    def cursor(self, name: str) -> _Cursor:
+    def cursor(self, name: str) -> Cursor:
         ...
 
     @overload
     def cursor(self, cursor_factory: Callable[..., T_cursor]) -> T_cursor:
         ...
 
-    def cursor(self, cursor_factory  = _Cursor, **kwargs): # type: ignore
+    def cursor(self, cursor_factory  = Cursor, **kwargs): # type: ignore
         """ Return a new cursor. By default the specialised cursor is returned.
         """
         return super().cursor(cursor_factory=cursor_factory, **kwargs)

nominatim/db/utils.py

@@ -7,14 +7,14 @@
 """
 Helper functions for handling DB accesses.
 """
-from typing import IO, Optional, Union
+from typing import IO, Optional, Union, Any, Iterable
 import subprocess
 import logging
 import gzip
 import io
 from pathlib import Path
 
-from nominatim.db.connection import get_pg_env
+from nominatim.db.connection import get_pg_env, Cursor
 from nominatim.errors import UsageError
 
 LOG = logging.getLogger()
@@ -84,20 +84,20 @@ class CopyBuffer:
     """ Data collector for the copy_from command.
     """
 
-    def __init__(self):
+    def __init__(self) -> None:
         self.buffer = io.StringIO()
 
 
-    def __enter__(self):
+    def __enter__(self) -> 'CopyBuffer':
         return self
 
 
-    def __exit__(self, exc_type, exc_value, traceback):
+    def __exit__(self, exc_type: Any, exc_value: Any, traceback: Any) -> None:
         if self.buffer is not None:
             self.buffer.close()
 
 
-    def add(self, *data):
+    def add(self, *data: Any) -> None:
         """ Add another row of data to the copy buffer.
         """
         first = True
@@ -113,9 +113,9 @@ class CopyBuffer:
         self.buffer.write('\n')
 
 
-    def copy_out(self, cur, table, columns=None):
+    def copy_out(self, cur: Cursor, table: str, columns: Optional[Iterable[str]] = None) -> None:
         """ Copy all collected data into the given table.
         """
         if self.buffer.tell() > 0:
             self.buffer.seek(0)
-            cur.copy_from(self.buffer, table, columns=columns)
+            cur.copy_from(self.buffer, table, columns=columns) # type: ignore[no-untyped-call]