Fix missing query-actions buttons for queries with date/datetime params.

The param `strings_only=True` caused params with type `time`, `date` and
`datetime` to not be converted to string by `NormalCursorWrapper._decode()`,
and in turn causes the json dumping to fail.

This change keeps `strings_only=True` for every type but datetime, date and
time, enabling conversion to string in those cases.

Fixes #882

debug_toolbar/panels/sql/tracking.py

@@ -1,5 +1,6 @@
 from __future__ import absolute_import, unicode_literals
 
+import datetime
 import json
 from threading import local
 from time import time
@@ -95,8 +96,10 @@ def _quote_params(self, params):
         return [self._quote_expr(p) for p in params]
 
     def _decode(self, param):
+        # make sure datetime, date and time are converted to string by force_text
+        CONVERT_TYPES = (datetime.datetime, datetime.date, datetime.time)
         try:
-            return force_text(param, strings_only=True)
+            return force_text(param, strings_only=not isinstance(param, CONVERT_TYPES))
         except UnicodeDecodeError:
             return '(encoded string)'
 
@@ -114,7 +117,7 @@ def _record(self, method, sql, params):
             _params = ''
             try:
                 _params = json.dumps([self._decode(p) for p in params])
-            except Exception:
+            except TypeError as e:
                 pass  # object not JSON serializable
 
             template_info = get_template_info()

tests/panels/test_sql.py

@@ -2,10 +2,12 @@
 
 from __future__ import absolute_import, unicode_literals
 
+import datetime
 import unittest
 
 from django.contrib.auth.models import User
 from django.db import connection
+from django.db.models import Count
 from django.db.utils import DatabaseError
 from django.shortcuts import render
 from django.test.utils import override_settings
@@ -69,6 +71,35 @@ def test_non_ascii_query(self):
         # ensure the panel renders correctly
         self.assertIn('café', self.panel.content)
 
+    def test_param_conversion(self):
+        self.assertEqual(len(self.panel._queries), 0)
+
+        list(
+            User.objects
+                .filter(first_name='Foo')
+                .filter(is_staff=True)
+                .filter(is_superuser=False)
+        )
+        list(
+            User.objects
+                .annotate(group_count=Count('groups__id'))
+                .filter(group_count__lt=10)
+                .filter(group_count__gt=1)
+        )
+        list(User.objects.filter(date_joined=datetime.datetime(2017, 12, 22, 16, 7, 1)))
+
+        self.panel.process_response(self.request, self.response)
+        self.panel.generate_stats(self.request, self.response)
+
+        # ensure query was logged
+        self.assertEqual(len(self.panel._queries), 3)
+
+        self.assertEqual(tuple([q[1]['params'] for q in self.panel._queries]), (
+            '["Foo", true, false]',
+            '[10, 1]',
+            '["2017-12-22 16:07:01"]'
+        ))
+
     def test_insert_content(self):
         """
         Test that the panel only inserts content after generate_stats and