Rename SQLPanel context var to control SQL access.

The current build started failing for py3.8+ because the inner
exception SQLQueryTriggered was raised in the test
test_cursor_wrapper_asyncio_ctx.

This was identified as being caused by sql.tracking.recording
being set to false. The name recording made it seem as if
this context var was controlling whether recording was occurring
or not. However, it's true functionality was preventing SQL
queries from being sent during the template panel's processing.

Renaming that context var to allow_sql is more indicative of
its purpose and makes the fixed test change clearer.

Author: tim-schilling

debug_toolbar/panels/sql/tracking.py

@@ -13,7 +13,10 @@
 except ImportError:
     PostgresJson = None
 
-recording = contextvars.ContextVar("debug-toolbar-recording", default=True)
+# Prevents SQL queries from being sent to the DB. It's used
+# by the TemplatePanel to prevent the toolbar from issuing
+# additional queries.
+allow_sql = contextvars.ContextVar("debug-toolbar-allow-sql", default=True)
 
 
 class SQLQueryTriggered(Exception):
@@ -32,7 +35,7 @@ def cursor(*args, **kwargs):
             # See:
             # https://github.com/jazzband/django-debug-toolbar/pull/615
             # https://github.com/jazzband/django-debug-toolbar/pull/896
-            if recording.get():
+            if allow_sql.get():
                 wrapper = NormalCursorWrapper
             else:
                 wrapper = ExceptionCursorWrapper
@@ -43,7 +46,7 @@ def chunked_cursor(*args, **kwargs):
             # solves https://github.com/jazzband/django-debug-toolbar/issues/1239
             cursor = connection._djdt_chunked_cursor(*args, **kwargs)
             if not isinstance(cursor, BaseCursorWrapper):
-                if recording.get():
+                if allow_sql.get():
                     wrapper = NormalCursorWrapper
                 else:
                     wrapper = ExceptionCursorWrapper

debug_toolbar/panels/templates/panel.py

@@ -13,7 +13,7 @@
 from django.utils.translation import gettext_lazy as _
 
 from debug_toolbar.panels import Panel
-from debug_toolbar.panels.sql.tracking import SQLQueryTriggered, recording
+from debug_toolbar.panels.sql.tracking import SQLQueryTriggered, allow_sql
 from debug_toolbar.panels.templates import views
 
 # Monkey-patch to enable the template_rendered signal. The receiver returns
@@ -118,7 +118,7 @@ def _store_template_info(self, sender, **kwargs):
                                 value.model._meta.label,
                             )
                         else:
-                            token = recording.set(False)
+                            token = allow_sql.set(False)
                             try:
                                 saferepr(value)  # this MAY trigger a db query
                             except SQLQueryTriggered:
@@ -130,7 +130,7 @@ def _store_template_info(self, sender, **kwargs):
                             else:
                                 temp_layer[key] = value
                             finally:
-                                recording.reset(token)
+                                allow_sql.reset(token)
                     pformatted = pformat(temp_layer)
                     self.pformat_layers.append((context_layer, pformatted))
                 context_list.append(pformatted)

tests/panels/test_sql.py

@@ -18,7 +18,6 @@
 
 from ..base import BaseTestCase
 from ..models import PostgresJSON
-from ..sync import database_sync_to_async
 
 
 def sql_call(use_iterator=False):
@@ -98,19 +97,21 @@ async def test_cursor_wrapper_async(self, mock_wrapper):
         wraps=sql_tracking.NormalCursorWrapper,
     )
     async def test_cursor_wrapper_asyncio_ctx(self, mock_wrapper):
-        self.assertTrue(sql_tracking.recording.get())
+        self.assertTrue(sql_tracking.allow_sql.get())
         await sync_to_async(sql_call)()
 
         async def task():
-            sql_tracking.recording.set(False)
-            # Calling this in another context requires the db connections
-            # to be closed properly.
-            await database_sync_to_async(sql_call)()
+            sql_tracking.allow_sql.set(False)
+            # By disabling sql_tracking.allow_sql, we are indicating that any
+            # future SQL queries should be stopped. If SQL query occurs,
+            # it raises an exception.
+            with self.assertRaises(sql_tracking.SQLQueryTriggered):
+                await sync_to_async(sql_call)()
 
         # Ensure this is called in another context
         await asyncio.create_task(task())
         # Because it was called in another context, it should not have affected ours
-        self.assertTrue(sql_tracking.recording.get())
+        self.assertTrue(sql_tracking.allow_sql.get())
         self.assertEqual(mock_wrapper.call_count, 1)
 
     def test_generate_server_timing(self):