Inherit from django.db.backends.utils.CursorWrapper

This switches the Debug Toolbar cursor wrappers to inherit from the
Django class django.db.backends.utils.CursorWrapper. This reduces some
of the code we need.

debug_toolbar/panels/sql/tracking.py

@@ -4,6 +4,7 @@
 from time import time
 
 import django.test.testcases
+from django.db.backends.utils import CursorWrapper
 from django.utils.encoding import force_str
 
 from debug_toolbar import settings as dt_settings
@@ -57,54 +58,47 @@ def cursor(*args, **kwargs):
                 wrapper = NormalCursorWrapper
             else:
                 wrapper = ExceptionCursorWrapper
-            return wrapper(cursor, connection, logger)
+            return wrapper(cursor.cursor, connection, logger)
 
         def chunked_cursor(*args, **kwargs):
             # prevent double wrapping
             # solves https://github.com/jazzband/django-debug-toolbar/issues/1239
             logger = connection._djdt_logger
             cursor = connection._djdt_chunked_cursor(*args, **kwargs)
-            if logger is not None and not isinstance(cursor, BaseCursorWrapper):
+            if logger is not None and not isinstance(cursor, DjDTCursorWrapper):
                 if allow_sql.get():
                     wrapper = NormalCursorWrapper
                 else:
                     wrapper = ExceptionCursorWrapper
-                return wrapper(cursor, connection, logger)
+                return wrapper(cursor.cursor, connection, logger)
             return cursor
 
         connection.cursor = cursor
         connection.chunked_cursor = chunked_cursor
 
 
-class BaseCursorWrapper:
-    pass
+class DjDTCursorWrapper(CursorWrapper):
+    def __init__(self, cursor, db, logger):
+        super().__init__(cursor, db)
+        # logger must implement a ``record`` method
+        self.logger = logger
 
 
-class ExceptionCursorWrapper(BaseCursorWrapper):
+class ExceptionCursorWrapper(DjDTCursorWrapper):
     """
     Wraps a cursor and raises an exception on any operation.
     Used in Templates panel.
     """
 
-    def __init__(self, cursor, db, logger):
-        pass
-
     def __getattr__(self, attr):
         raise SQLQueryTriggered()
 
 
-class NormalCursorWrapper(BaseCursorWrapper):
+class NormalCursorWrapper(DjDTCursorWrapper):
     """
     Wraps a cursor and logs queries.
     """
 
-    def __init__(self, cursor, db, logger):
-        self.cursor = cursor
-        # Instance of a BaseDatabaseWrapper subclass
-        self.db = db
-        # logger must implement a ``record`` method
-        self.logger = logger
-
     def _quote_expr(self, element):
         if isinstance(element, str):
             return "'%s'" % element.replace("'", "''")
@@ -246,22 +240,10 @@ def _record(self, method, sql, params):
             self.logger.record(**params)
 
     def callproc(self, procname, params=None):
-        return self._record(self.cursor.callproc, procname, params)
+        return self._record(super().callproc, procname, params)
 
     def execute(self, sql, params=None):
-        return self._record(self.cursor.execute, sql, params)
+        return self._record(super().execute, sql, params)
 
     def executemany(self, sql, param_list):
-        return self._record(self.cursor.executemany, sql, param_list)
-
-    def __getattr__(self, attr):
-        return getattr(self.cursor, attr)
-
-    def __iter__(self):
-        return iter(self.cursor)
-
-    def __enter__(self):
-        return self
-
-    def __exit__(self, type, value, traceback):
-        self.close()
+        return self._record(super().executemany, sql, param_list)