Merge pull request #6781 from jangsutsr/6084_revert_adding_custom_paginator

Revert adding custom paginator

awx/api/pagination.py

@@ -1,78 +1,16 @@
 # Copyright (c) 2015 Ansible, Inc.
 # All Rights Reserved.
 
-# Django
-from django.core.paginator import Paginator as DjangoPaginator
-from django.core.paginator import PageNotAnInteger, EmptyPage
-from django.db import connections
-
 # Django REST Framework
 from django.conf import settings
 from rest_framework import pagination
 from rest_framework.utils.urls import replace_query_param
 
 
-class Paginator(DjangoPaginator):
-
-    def __init__(self, object_list, per_page, orphans=0, allow_empty_first_page=True):
-        self.count_field = None
-        # Based on http://stackoverflow.com/questions/156114/best-way-to-get-result-count-before-limit-was-applied
-        # With PostgreSQL, we can use a window function to include the total
-        # count of results (before limit and offset are applied) as an extra
-        # column and avoid having to issue a separate COUNT(*) query.
-        if hasattr(object_list, 'extra'):
-            if connections[getattr(object_list, 'db', None) or 'default'].vendor == 'postgresql':
-                object_list = object_list.extra(select=dict(__count='COUNT(*) OVER()'))
-                self.count_field = '__count'
-        super(Paginator, self).__init__(object_list, per_page, orphans, allow_empty_first_page)
-        assert self.orphans == 0
-
-    def validate_number(self, number, check_num_pages=True):
-        """
-        Validates the given 1-based page number.
-        """
-        try:
-            number = int(number)
-        except (TypeError, ValueError):
-            raise PageNotAnInteger('That page number is not an integer')
-        if number < 1:
-            raise EmptyPage('That page number is less than 1')
-        # Optionally skip checking num_pages, since that will result in a
-        # COUNT(*) query.
-        if check_num_pages and number > self.num_pages:
-            if number == 1 and self.allow_empty_first_page:
-                pass
-            else:
-                raise EmptyPage('That page contains no results')
-        return number
-
-    def page(self, number):
-        """
-        Returns a Page object for the given 1-based page number.
-        """
-        number = self.validate_number(number, check_num_pages=bool(self.count_field is None))
-        bottom = (number - 1) * self.per_page
-        top = bottom + self.per_page
-        sub_list = self.object_list[bottom:top]
-        if self.count_field and self._count is None:
-            # Execute one query to fetch all results.
-            sub_list = list(sub_list)
-            try:
-                # Get the total count from the first result.
-                self._count = getattr(sub_list[0], self.count_field)
-            except IndexError:
-                # If no results were returned, we still don't know the total
-                # count, but do know that we've reached an empty page.
-                if number > 1 or not self.allow_empty_first_page:
-                    raise EmptyPage('That page contains no results')
-        return self._get_page(sub_list, number, self)
-
-
 class Pagination(pagination.PageNumberPagination):
 
     page_size_query_param = 'page_size'
     max_page_size = settings.MAX_PAGE_SIZE
-    django_paginator_class = Paginator
 
     def get_next_link(self):
         if not self.page.has_next():

awx/main/tests/functional/api/test_pagination.py

@@ -0,0 +1,40 @@
+import pytest
+
+from awx.main.models.inventory import Group, Host
+from awx.api.pagination import Pagination
+
+
+@pytest.fixture
+def host(inventory):
+    def handler(name, groups):
+        h = Host(name=name, inventory=inventory)
+        h.save()
+        h = Host.objects.get(name=name, inventory=inventory)
+        for g in groups:
+            h.groups.add(g)
+        h.save()
+        h = Host.objects.get(name=name, inventory=inventory)
+        return h
+    return handler
+
+
+@pytest.fixture
+def group(inventory):
+    def handler(name):
+        g = Group(name=name, inventory=inventory)
+        g.save()
+        g = Group.objects.get(name=name, inventory=inventory)
+        return g
+    return handler
+
+
+@pytest.mark.django_db
+def test_pagination_backend_output_correct_total_count(group, host):
+    # NOTE: this test might not be db-backend-agnostic. Manual tests might be needed also
+    g1 = group('pg_group1')
+    g2 = group('pg_group2')
+    host('pg_host1', [g1, g2])
+    queryset = Host.objects.filter(groups__name__in=('pg_group1', 'pg_group2')).distinct()
+    p = Pagination().django_paginator_class(queryset, 10)
+    p.page(1)
+    assert p.count == 1