Stop Answer.get_absolute_url() from making any DB queries.

apps/questions/fixtures/questions.json

@@ -41,6 +41,20 @@
             "num_answers": 0
         }
     },
+    {
+        "pk": 4,
+        "model": "questions.question",
+        "fields": {
+            "status": 1,
+            "updated": "2010-06-17 19:47:34",
+            "creator": 47963,
+            "is_locked": false,
+            "created": "2010-06-17 19:47:34",
+            "content": "It's a marvellous night for an audio lolrus foo.",
+            "title": "lolrus too?",
+            "num_answers": 2
+        }
+    },
     {
         "pk": 1,
         "model": "questions.questionmetadata",
@@ -125,5 +139,29 @@
             "content": "An answer & stuff.",
             "upvotes": 0
         }
+    },
+    {
+        "pk": 2,
+        "model": "questions.answer",
+        "fields": {
+            "updated": "2010-06-23 19:48:00",
+            "created": "2010-06-23 19:48:00",
+            "creator": 118533,
+            "question": 4,
+            "content": "An answer & stuff, too.",
+            "upvotes": 0
+        }
+    },
+    {
+        "pk": 3,
+        "model": "questions.answer",
+        "fields": {
+            "updated": "2010-06-24 19:48:00",
+            "created": "2010-06-24 19:48:00",
+            "creator": 118533,
+            "question": 4,
+            "content": "An answer & stuff, too.",
+            "upvotes": 0
+        }
     }
 ]

apps/questions/models.py

@@ -21,7 +21,8 @@ from sumo.helpers import urlparams
 import questions as constants
 from questions.tags import add_existing_tag
 from .question_config import products
-from .tasks import update_question_votes, build_answer_notification
+from .tasks import (update_question_votes, build_answer_notification,
+                    update_answer_pages)
 from upload.models import ImageAttachment
 
 
@@ -252,6 +253,7 @@ class Answer(ModelBase):
     updated_by = models.ForeignKey(User, null=True,
                                    related_name='answers_updated')
     upvotes = models.IntegerField(default=0, db_index=True)
+    page = models.IntegerField(default=1)
 
     images = generic.GenericRelation(ImageAttachment)
     flags = generic.GenericRelation(FlaggedObject)
@@ -274,7 +276,10 @@ class Answer(ModelBase):
 
         new = self.id is None
 
-        if not new:
+        if new:
+            page = self.question.num_answers / constants.ANSWERS_PER_PAGE + 1
+            self.page = page
+        else:
             self.updated = datetime.now()
 
         super(Answer, self).save(*args, **kwargs)
@@ -305,21 +310,15 @@ class Answer(ModelBase):
 
         super(Answer, self).delete(*args, **kwargs)
 
-    @property
-    def page(self):
-        """Get the page of the question on which this answer is found."""
-        t = self.question
-        earlier = t.answers.filter(created__lte=self.created).count() - 1
-        if earlier < 1:
-            return 1
-        return earlier / constants.ANSWERS_PER_PAGE + 1
+        update_answer_pages.delay(question)
 
     def get_absolute_url(self):
         query = {}
         if self.page > 1:
             query = {'page': self.page}
 
-        url = self.question.get_absolute_url()
+        url = reverse('questions.answers',
+                      kwargs={'question_id': self.question_id})
         return urlparams(url, hash='answer-%s' % self.id, **query)
 
     @property

apps/questions/tasks.py

@@ -12,6 +12,7 @@ from celery.decorators import task
 from tower import ugettext as _
 
 from notifications.tasks import send_notification
+from questions import ANSWERS_PER_PAGE
 from sumo.urlresolvers import reverse
 
 
@@ -92,3 +93,15 @@ def send_confirmation_email(question):
                                 'confirm_url': url,
                                 'host': Site.objects.get_current().domain}))
     send_mail(subject, content, from_address, [question.creator.email])
+
+
+@task(rate_limit='4/m')
+def update_answer_pages(question):
+    log.debug('Recalculating answer page numbers for question %s: %s' %
+              (question.pk, question.title))
+
+    i = 0
+    for answer in question.answers.using('default').order_by('created').all():
+        answer.page = i / ANSWERS_PER_PAGE + 1
+        answer.save(no_update=True, no_notify=True)
+        i += 1

apps/questions/tests/test_models.py

@@ -10,6 +10,7 @@ from flagit.models import FlaggedObject
 from questions.models import (Question, QuestionMetaData, Answer,
                               _tenths_version)
 from questions.tags import add_existing_tag
+from questions.tasks import update_answer_pages
 from questions.tests import TestCaseBase, TaggingTestCaseBase, tags_eq
 from questions.question_config import products
 
@@ -105,13 +106,32 @@ class TestAnswer(TestCaseBase):
         question = Question.objects.get(pk=question.id)
         eq_(question.solution, None)
 
+    def test_update_page_task(self):
+        answer = Answer.objects.get(pk=1)
+        answer.page = 4
+        answer.save()
+        answer = Answer.objects.get(pk=1)
+        assert answer.page == 4
+        update_answer_pages(answer.question)
+        a = Answer.objects.get(pk=1)
+        assert a.page == 1
+
+    def test_delete_updates_pages(self):
+        a1 = Answer.objects.get(pk=2)
+        a2 = Answer.objects.get(pk=3)
+        a1.page = 7
+        a1.save()
+        a2.delete()
+        a3 = Answer.objects.filter(question=a1.question)[0]
+        assert a3.page == 1, "Page was %s" % a3.page
+
     def test_creator_num_posts(self):
         """Test retrieval of post count for creator of a particular answer"""
         question = Question.objects.all()[0]
         answer = Answer(question=question, creator_id=47963,
                         content="Test Answer")
 
-        eq_(answer.creator_num_posts, 2)
+        eq_(answer.creator_num_posts, 4)
 
     def test_creator_num_answers(self):
         """Test retrieval of answer count for creator of a particular answer"""

apps/questions/tests/test_templates.py

@@ -779,7 +779,7 @@ class QuestionsTemplateTestCase(TestCaseBase):
         response = self.client.get(url_)
         doc = pq(response.content)
         eq_('active', doc('div#filter ul li')[4].attrib['class'])
-        eq_(3, len(doc('ol.questions li')))
+        eq_(4, len(doc('ol.questions li')))
 
         # solve one question then verify that it doesn't show up
         answer = Answer.objects.all()[0]
@@ -787,7 +787,7 @@ class QuestionsTemplateTestCase(TestCaseBase):
         answer.question.save()
         response = self.client.get(url_)
         doc = pq(response.content)
-        eq_(2, len(doc('ol.questions li')))
+        eq_(3, len(doc('ol.questions li')))
         eq_(0, len(doc('ol.questions li#question-%s' % answer.question.id)))
 
     def _my_contributions_test_helper(self, username, expected_qty):
@@ -801,10 +801,10 @@ class QuestionsTemplateTestCase(TestCaseBase):
 
     def test_my_contributions_filter(self):
         # jsocol should have 2 questions in his contributions
-        self._my_contributions_test_helper('jsocol', 2)
+        self._my_contributions_test_helper('jsocol', 3)
 
         # pcraciunoiu should have 2 questions in his contributions'
-        self._my_contributions_test_helper('pcraciunoiu', 2)
+        self._my_contributions_test_helper('pcraciunoiu', 3)
 
         # rrosario should have 0 questions in his contributions
         self._my_contributions_test_helper('rrosario', 0)

apps/search/tests/test_search.py

@@ -236,7 +236,7 @@ class SearchTest(SphinxTestCase):
         qs = {'a': 1, 'format': 'json', 'page': 'invalid'}
         response = self.client.get(reverse('search'), qs)
         eq_(200, response.status_code)
-        eq_(4, json.loads(response.content)['total'])
+        eq_(5, json.loads(response.content)['total'])
 
     def test_search_metrics(self):
         """Ensure that query strings are added to search results"""
@@ -266,7 +266,7 @@ class SearchTest(SphinxTestCase):
     def test_category_invalid(self):
         qs = {'a': 1, 'w': 3, 'format': 'json', 'category': 'invalid'}
         response = self.client.get(reverse('search'), qs)
-        eq_(4, json.loads(response.content)['total'])
+        eq_(5, json.loads(response.content)['total'])
 
     def test_no_filter(self):
         """Test searching with no filters."""
@@ -363,7 +363,7 @@ class SearchTest(SphinxTestCase):
         qs = {'a': 1, 'w': 2, 'format': 'json',
               'sortby': 1, 'updated_date': '06/20/2010'}
         updated_vals = (
-            (1, '/3'),
+            (1, '/4'),
             (2, '/2'),
         )
 
@@ -380,7 +380,7 @@ class SearchTest(SphinxTestCase):
         qs = {'a': 1, 'w': 2, 'format': 'json',
               'updated': 1, 'updated_date': 'invalid'}
         response = self.client.get(reverse('search'), qs)
-        eq_(3, json.loads(response.content)['total'])
+        eq_(4, json.loads(response.content)['total'])
 
     def test_updated_nonexistent(self):
         """updated is set while updated_date is left out of the query."""
@@ -404,7 +404,7 @@ class SearchTest(SphinxTestCase):
         author_vals = (
             ('DoesNotExist', 0),
             ('jsocol', 2),
-            ('pcraciunoiu', 1),
+            ('pcraciunoiu', 2),
         )
 
         for author, total in author_vals:

migrations/34-answer-page.sql

@@ -0,0 +1,14 @@
+-- Model: Answer
+ALTER TABLE `questions_answer`
+    ADD `page` integer default 1;
+
+-- Set page numbers for existing answers.
+UPDATE questions_answer a
+SET
+    page = (
+        SELECT COUNT(*)
+        FROM (
+            SELECT id, question_id, created
+            FROM questions_answer) b
+        WHERE b.question_id = a.question_id AND b.created < a.created
+        ) / 20 + 1;