Add Django Debug Toolbar, and add a failing test for query explosions

.gitignore

@@ -40,4 +40,7 @@ pip-delete-this-directory.txt
 # VirtualEnv
 .venv/
 
+# Developers
 *.sw*
+manage.py
+.DS_Store

example/models.py

@@ -28,6 +28,9 @@ class TaggedItem(BaseModel):
     def __str__(self):
         return self.tag
 
+    class Meta:
+        ordering = ('id',)
+
 
 @python_2_unicode_compatible
 class Blog(BaseModel):
@@ -38,6 +41,9 @@ class Blog(BaseModel):
     def __str__(self):
         return self.name
 
+    class Meta:
+        ordering = ('id',)
+
 
 @python_2_unicode_compatible
 class Author(BaseModel):
@@ -47,6 +53,9 @@ class Author(BaseModel):
     def __str__(self):
         return self.name
 
+    class Meta:
+        ordering = ('id',)
+
 
 @python_2_unicode_compatible
 class AuthorBio(BaseModel):
@@ -56,6 +65,9 @@ class AuthorBio(BaseModel):
     def __str__(self):
         return self.author.name
 
+    class Meta:
+        ordering = ('id',)
+
 
 @python_2_unicode_compatible
 class Entry(BaseModel):
@@ -73,6 +85,9 @@ class Entry(BaseModel):
     def __str__(self):
         return self.headline
 
+    class Meta:
+        ordering = ('id',)
+
 
 @python_2_unicode_compatible
 class Comment(BaseModel):
@@ -87,6 +102,9 @@ class Comment(BaseModel):
     def __str__(self):
         return self.body
 
+    class Meta:
+        ordering = ('id',)
+
 
 class Project(PolymorphicModel):
     topic = models.CharField(max_length=30)

example/settings/dev.py

@@ -25,6 +25,7 @@
     'rest_framework',
     'polymorphic',
     'example',
+    'debug_toolbar',
 ]
 
 TEMPLATES = [
@@ -58,7 +59,11 @@
 
 PASSWORD_HASHERS = ('django.contrib.auth.hashers.UnsaltedMD5PasswordHasher', )
 
-MIDDLEWARE_CLASSES = ()
+MIDDLEWARE_CLASSES = (
+    'debug_toolbar.middleware.DebugToolbarMiddleware',
+)
+
+INTERNAL_IPS = ('127.0.0.1', )
 
 JSON_API_FORMAT_KEYS = 'camelize'
 JSON_API_FORMAT_TYPES = 'camelize'
@@ -74,7 +79,13 @@
     ),
     'DEFAULT_RENDERER_CLASSES': (
         'rest_framework_json_api.renderers.JSONRenderer',
-        'rest_framework.renderers.BrowsableAPIRenderer',
+
+        # If you're performance testing, you will want to use the browseable API
+        # without forms, as the forms can generate their own queries.
+        # If performance testing, enable:
+        'example.utils.BrowsableAPIRendererWithoutForms',
+        # Otherwise, to play around with the browseable API, enable:
+        #'rest_framework.renderers.BrowsableAPIRenderer',
     ),
     'DEFAULT_METADATA_CLASS': 'rest_framework_json_api.metadata.JSONAPIMetadata',
 }

example/tests/test_performance.py

@@ -0,0 +1,55 @@
+from django.utils import timezone
+from rest_framework.test import APITestCase
+
+from example.factories import CommentFactory
+from example.models import Author, Blog, Comment, Entry
+
+
+class PerformanceTestCase(APITestCase):
+    def setUp(self):
+        self.author = Author.objects.create(name='Super powerful superhero', email='i.am@lost.com')
+        self.blog = Blog.objects.create(name='Some Blog', tagline="It's a blog")
+        self.other_blog = Blog.objects.create(name='Other blog', tagline="It's another blog")
+        self.first_entry = Entry.objects.create(
+            blog=self.blog,
+            headline='headline one',
+            body_text='body_text two',
+            pub_date=timezone.now(),
+            mod_date=timezone.now(),
+            n_comments=0,
+            n_pingbacks=0,
+            rating=3
+        )
+        self.second_entry = Entry.objects.create(
+            blog=self.blog,
+            headline='headline two',
+            body_text='body_text one',
+            pub_date=timezone.now(),
+            mod_date=timezone.now(),
+            n_comments=0,
+            n_pingbacks=0,
+            rating=1
+        )
+        self.comment = Comment.objects.create(entry=self.first_entry)
+        CommentFactory.create_batch(50)
+
+    def test_query_count_no_includes(self):
+        """ We expect a simple list view to issue only two queries.
+
+        1. The number of results in the set (e.g. a COUNT query), only necessary because we're using PageNumberPagination
+        2. The SELECT query for the set
+        """
+        with self.assertNumQueries(2):
+            response = self.client.get('/comments?page_size=25')
+            self.assertEqual(len(response.data['results']), 25)
+
+    def test_query_count_include_author(self):
+        """ We expect a list view with an include have three queries:
+
+        1. Primary resource COUNT query
+        2. Primary resource SELECT
+        3. Author's prefetched
+        """
+        with self.assertNumQueries(3):
+            response = self.client.get('/comments?include=author&page_size=25')
+            self.assertEqual(len(response.data['results']), 25)

example/tests/test_views.py

@@ -4,11 +4,10 @@
 from django.utils import timezone
 from rest_framework.reverse import reverse
 from rest_framework.test import APITestCase, force_authenticate
-
 from rest_framework_json_api.utils import format_resource_type
 
 from . import TestBase
-from .. import views
+from .. import factories, views
 from example.models import Author, Blog, Comment, Entry
 
 

example/urls.py

@@ -1,3 +1,4 @@
+from django.conf import settings
 from django.conf.urls import include, url
 from rest_framework import routers
 
@@ -22,3 +23,10 @@
 urlpatterns = [
     url(r'^', include(router.urls)),
 ]
+
+
+if settings.DEBUG:
+    import debug_toolbar
+    urlpatterns = [
+        url(r'^__debug__/', include(debug_toolbar.urls)),
+    ] + urlpatterns

example/utils.py

@@ -0,0 +1,20 @@
+from rest_framework.renderers import BrowsableAPIRenderer
+
+
+class BrowsableAPIRendererWithoutForms(BrowsableAPIRenderer):
+    """Renders the browsable api, but excludes the forms."""
+
+    def get_context(self, *args, **kwargs):
+        ctx = super().get_context(*args, **kwargs)
+        ctx['display_edit_forms'] = False
+        return ctx
+
+    def show_form_for_method(self, view, method, request, obj):
+        """We never want to do this! So just return False."""
+        return False
+
+    def get_rendered_html_form(self, data, view, method, request):
+        """Why render _any_ forms at all. This method should return
+        rendered HTML, so let's simply return an empty string.
+        """
+        return ""

example/views.py

@@ -1,10 +1,9 @@
 import rest_framework.parsers
 import rest_framework.renderers
-from rest_framework import exceptions
-
 import rest_framework_json_api.metadata
 import rest_framework_json_api.parsers
 import rest_framework_json_api.renderers
+from rest_framework import exceptions
 from rest_framework_json_api.utils import format_drf_errors
 from rest_framework_json_api.views import ModelViewSet, RelationshipView
 

requirements-development.txt

@@ -10,4 +10,6 @@ recommonmark
 Sphinx
 sphinx_rtd_theme
 tox
+mock
+django-debug-toolbar
 packaging==16.8

rest_framework_json_api/relations.py

@@ -1,12 +1,17 @@
 import collections
 import json
+from collections import OrderedDict
+
+import six
 
 import inflection
+from django.core.exceptions import ImproperlyConfigured
+from django.core.urlresolvers import NoReverseMatch
 from django.utils.translation import ugettext_lazy as _
 from rest_framework.fields import MISSING_ERROR_MESSAGE
-from rest_framework.relations import *  # noqa: F403
+from rest_framework.relations import MANY_RELATION_KWARGS, PrimaryKeyRelatedField
+from rest_framework.reverse import reverse
 from rest_framework.serializers import Serializer
-
 from rest_framework_json_api.exceptions import Conflict
 from rest_framework_json_api.utils import (
     Hyperlink,

rest_framework_json_api/serializers.py

@@ -4,7 +4,6 @@
 from django.utils.translation import ugettext_lazy as _
 from rest_framework.exceptions import ParseError
 from rest_framework.serializers import *  # noqa: F403
-
 from rest_framework_json_api.exceptions import Conflict
 from rest_framework_json_api.relations import ResourceRelatedField
 from rest_framework_json_api.utils import (