Fixed #35945 -- Added async interface to Paginator.

AUTHORS

@@ -500,6 +500,7 @@ answer newbie questions, and generally made Django that much better:
     Jens Page
     Jensen Cochran <jensen.cochran@gmail.com>
     Jeong-Min Lee <falsetru@gmail.com>
+    Jeong-Wook Lee <devwookkl@gmail.com>
     Jérémie Blaser <blaserje@gmail.com>
     Jeremy Bowman <https://github.com/jmbowman>
     Jeremy Carbaugh <jcarbaugh@gmail.com>

django/core/paginator.py

@@ -1,8 +1,11 @@
 import collections.abc
 import inspect
 import warnings
+from asyncio import iscoroutinefunction
 from math import ceil
 
+from asgiref.sync import sync_to_async
+
 from django.utils.functional import cached_property
 from django.utils.inspect import method_has_no_args
 from django.utils.translation import gettext_lazy as _
@@ -24,7 +27,7 @@ class EmptyPage(InvalidPage):
     pass
 
 
-class Paginator:
+class BasePaginator:
     # Translators: String used to replace omitted page numbers in elided page
     # range generated by paginators, e.g. [1, 2, '…', 5, 6, 7, '…', 9, 10].
     ELLIPSIS = _("…")
@@ -53,11 +56,74 @@ class Paginator:
             else self.default_error_messages | error_messages
         )
 
-    def __iter__(self):
-        for page_number in self.page_range:
-            yield self.page(page_number)
+    def _check_object_list_is_ordered(self):
+        """
+        Warn if self.object_list is unordered (typically a QuerySet).
+        """
+        ordered = getattr(self.object_list, "ordered", None)
+        if ordered is not None and not ordered:
+            obj_list_repr = (
+                "{} {}".format(
+                    self.object_list.model, self.object_list.__class__.__name__
+                )
+                if hasattr(self.object_list, "model")
+                else "{!r}".format(self.object_list)
+            )
+            warnings.warn(
+                "Pagination may yield inconsistent results with an unordered "
+                "object_list: {}.".format(obj_list_repr),
+                UnorderedObjectListWarning,
+                stacklevel=3,
+            )
 
-    def validate_number(self, number):
+    def _get_elided_page_range(
+        self, number, num_pages, page_range, on_each_side=3, on_ends=2
+    ):
+        """
+        Return a 1-based range of pages with some values elided.
+
+        If the page range is larger than a given size, the whole range is not
+        provided and a compact form is returned instead, e.g. for a paginator
+        with 50 pages, if page 43 were the current page, the output, with the
+        default arguments, would be:
+
+            1, 2, …, 40, 41, 42, 43, 44, 45, 46, …, 49, 50.
+        """
+        if num_pages <= (on_each_side + on_ends) * 2:
+            for page in page_range:
+                yield page
+            return
+
+        if number > (1 + on_each_side + on_ends) + 1:
+            for page in range(1, on_ends + 1):
+                yield page
+            yield self.ELLIPSIS
+            for page in range(number - on_each_side, number + 1):
+                yield page
+        else:
+            for page in range(1, number + 1):
+                yield page
+
+        if number < (num_pages - on_each_side - on_ends) - 1:
+            for page in range(number + 1, number + on_each_side + 1):
+                yield page
+            yield self.ELLIPSIS
+            for page in range(num_pages - on_ends + 1, num_pages + 1):
+                yield page
+        else:
+            for page in range(number + 1, num_pages + 1):
+                yield page
+
+    def _get_page(self, *args, **kwargs):
+        """
+        Return an instance of a single page.
+
+        This hook can be used by subclasses to use an alternative to the
+        standard :cls:`Page` object.
+        """
+        return Page(*args, **kwargs)
+
+    def _validate_number(self, number, num_pages):
         """Validate the given 1-based page number."""
         try:
             if isinstance(number, float) and not number.is_integer():
@@ -67,10 +133,19 @@ class Paginator:
             raise PageNotAnInteger(self.error_messages["invalid_page"])
         if number < 1:
             raise EmptyPage(self.error_messages["min_page"])
-        if number > self.num_pages:
+        if number > num_pages:
             raise EmptyPage(self.error_messages["no_results"])
         return number
 
+
+class Paginator(BasePaginator):
+    def __iter__(self):
+        for page_number in self.page_range:
+            yield self.page(page_number)
+
+    def validate_number(self, number):
+        return self._validate_number(number, self.num_pages)
+
     def get_page(self, number):
         """
         Return a valid page, even if the page argument isn't a number or isn't
@@ -93,15 +168,6 @@ class Paginator:
             top = self.count
         return self._get_page(self.object_list[bottom:top], number, self)
 
-    def _get_page(self, *args, **kwargs):
-        """
-        Return an instance of a single page.
-
-        This hook can be used by subclasses to use an alternative to the
-        standard :cls:`Page` object.
-        """
-        return Page(*args, **kwargs)
-
     @cached_property
     def count(self):
         """Return the total number of objects, across all pages."""
@@ -126,56 +192,105 @@ class Paginator:
         """
         return range(1, self.num_pages + 1)
 
-    def _check_object_list_is_ordered(self):
-        """
-        Warn if self.object_list is unordered (typically a QuerySet).
-        """
-        ordered = getattr(self.object_list, "ordered", None)
-        if ordered is not None and not ordered:
-            obj_list_repr = (
-                "{} {}".format(
-                    self.object_list.model, self.object_list.__class__.__name__
-                )
-                if hasattr(self.object_list, "model")
-                else "{!r}".format(self.object_list)
-            )
-            warnings.warn(
-                "Pagination may yield inconsistent results with an unordered "
-                "object_list: {}.".format(obj_list_repr),
-                UnorderedObjectListWarning,
-                stacklevel=3,
-            )
-
     def get_elided_page_range(self, number=1, *, on_each_side=3, on_ends=2):
-        """
-        Return a 1-based range of pages with some values elided.
-
-        If the page range is larger than a given size, the whole range is not
-        provided and a compact form is returned instead, e.g. for a paginator
-        with 50 pages, if page 43 were the current page, the output, with the
-        default arguments, would be:
-
-            1, 2, …, 40, 41, 42, 43, 44, 45, 46, …, 49, 50.
-        """
         number = self.validate_number(number)
+        yield from self._get_elided_page_range(
+            number, self.num_pages, self.page_range, on_each_side, on_ends
+        )
 
-        if self.num_pages <= (on_each_side + on_ends) * 2:
-            yield from self.page_range
-            return
 
-        if number > (1 + on_each_side + on_ends) + 1:
-            yield from range(1, on_ends + 1)
-            yield self.ELLIPSIS
-            yield from range(number - on_each_side, number + 1)
+class AsyncPaginator(BasePaginator):
+    def __init__(
+        self,
+        object_list,
+        per_page,
+        orphans=0,
+        allow_empty_first_page=True,
+        error_messages=None,
+    ):
+        super().__init__(
+            object_list, per_page, orphans, allow_empty_first_page, error_messages
+        )
+        self._cache_acount = None
+        self._cache_anum_pages = None
+
+    async def __aiter__(self):
+        page_range = await self.apage_range()
+        for page_number in page_range:
+            yield await self.apage(page_number)
+
+    async def avalidate_number(self, number):
+        num_pages = await self.anum_pages()
+        return self._validate_number(number, num_pages)
+
+    async def aget_page(self, number):
+        """See Paginator.get_page()."""
+        try:
+            number = await self.avalidate_number(number)
+        except PageNotAnInteger:
+            number = 1
+        except EmptyPage:
+            number = await self.anum_pages()
+        return await self.apage(number)
+
+    async def apage(self, number):
+        """See Paginator.page()."""
+        number = await self.avalidate_number(number)
+        bottom = (number - 1) * self.per_page
+        top = bottom + self.per_page
+        count = await self.acount()
+        if top + self.orphans >= count:
+            top = count
+
+        return self._get_page(self.object_list[bottom:top], number, self)
+
+    def _get_page(self, *args, **kwargs):
+        return AsyncPage(*args, **kwargs)
+
+    async def acount(self):
+        """See Paginator.count()."""
+        if self._cache_acount is not None:
+            return self._cache_acount
+        c = getattr(self.object_list, "acount", None)
+        if (
+            iscoroutinefunction(c)
+            and not inspect.isbuiltin(c)
+            and method_has_no_args(c)
+        ):
+            count = await c()
         else:
-            yield from range(1, number + 1)
+            count = len(self.object_list)
 
-        if number < (self.num_pages - on_each_side - on_ends) - 1:
-            yield from range(number + 1, number + on_each_side + 1)
-            yield self.ELLIPSIS
-            yield from range(self.num_pages - on_ends + 1, self.num_pages + 1)
-        else:
-            yield from range(number + 1, self.num_pages + 1)
+        self._cache_acount = count
+        return count
+
+    async def anum_pages(self):
+        """See Paginator.num_pages()."""
+        if self._cache_anum_pages is not None:
+            return self._cache_anum_pages
+        count = await self.acount()
+        if count == 0 and not self.allow_empty_first_page:
+            self._cache_anum_pages = 0
+            return self._cache_anum_pages
+        hits = max(1, count - self.orphans)
+        num_pages = ceil(hits / self.per_page)
+
+        self._cache_anum_pages = num_pages
+        return num_pages
+
+    async def apage_range(self):
+        """See Paginator.page_range()"""
+        num_pages = await self.anum_pages()
+        return range(1, num_pages + 1)
+
+    async def aget_elided_page_range(self, number=1, *, on_each_side=3, on_ends=2):
+        number = await self.avalidate_number(number)
+        num_pages = await self.anum_pages()
+        page_range = await self.apage_range()
+        for page in self._get_elided_page_range(
+            number, num_pages, page_range, on_each_side, on_ends
+        ):
+            yield page
 
 
 class Page(collections.abc.Sequence):
@@ -236,3 +351,96 @@ class Page(collections.abc.Sequence):
         if self.number == self.paginator.num_pages:
             return self.paginator.count
         return self.number * self.paginator.per_page
+
+
+class AsyncPage:
+    def __init__(self, object_list, number, paginator):
+        self.object_list = object_list
+        self.number = number
+        self.paginator = paginator
+
+    def __repr__(self):
+        return "<Async Page %s>" % self.number
+
+    async def __aiter__(self):
+        if hasattr(self.object_list, "__aiter__"):
+            async for obj in self.object_list:
+                yield obj
+        else:
+            for obj in self.object_list:
+                yield obj
+
+    def __len__(self):
+        if not isinstance(self.object_list, list):
+            raise TypeError(
+                "AsyncPage.aget_object_list() must be awaited before calling len()."
+            )
+        return len(self.object_list)
+
+    def __reversed__(self):
+        if not isinstance(self.object_list, list):
+            raise TypeError(
+                "AsyncPage.aget_object_list() "
+                "must be awaited before calling reversed()."
+            )
+
+        return reversed(self.object_list)
+
+    def __getitem__(self, index):
+        if not isinstance(index, (int, slice)):
+            raise TypeError(
+                "AsyncPage indices must be integers or slices, not %s."
+                % type(index).__name__
+            )
+
+        if not isinstance(self.object_list, list):
+            raise TypeError(
+                "AsyncPage.aget_object_list() must be awaited before using indexing."
+            )
+        return self.object_list[index]
+
+    async def aget_object_list(self):
+        """
+        Returns self.object_list as a list.
+
+        This method must be awaited before AsyncPage can be
+        treated as a sequence of self.object_list.
+        """
+        if not isinstance(self.object_list, list):
+            if hasattr(self.object_list, "__aiter__"):
+                self.object_list = [obj async for obj in self.object_list]
+            else:
+                self.object_list = await sync_to_async(list)(self.object_list)
+        return self.object_list
+
+    async def ahas_next(self):
+        num_pages = await self.paginator.anum_pages()
+        return self.number < num_pages
+
+    async def ahas_previous(self):
+        return self.number > 1
+
+    async def ahas_other_pages(self):
+        has_previous = await self.ahas_previous()
+        has_next = await self.ahas_next()
+        return has_previous or has_next
+
+    async def anext_page_number(self):
+        return await self.paginator.avalidate_number(self.number + 1)
+
+    async def aprevious_page_number(self):
+        return await self.paginator.avalidate_number(self.number - 1)
+
+    async def astart_index(self):
+        """See Page.start_index()."""
+        count = await self.paginator.acount()
+        if count == 0:
+            return 0
+        return (self.paginator.per_page * (self.number - 1)) + 1
+
+    async def aend_index(self):
+        """See Page.end_index()."""
+        num_pages = await self.paginator.anum_pages()
+        if self.number == num_pages:
+            return await self.paginator.acount()
+        return self.number * self.paginator.per_page

docs/ref/paginator.txt

@@ -161,6 +161,30 @@ Attributes
 
     A 1-based range iterator of page numbers, e.g. yielding ``[1, 2, 3, 4]``.
 
+``AsyncPaginator`` class
+========================
+
+.. versionadded:: 6.0
+
+.. class:: AsyncPaginator(object_list, per_page, orphans=0, allow_empty_first_page=True, error_messages=None)
+
+    Asynchronous version of :class:`Paginator`.
+
+    ``AsyncPaginator`` has the same attributes and signatures as
+    :class:`Paginator`, with the following exceptions:
+
+    * The attribute :attr:`.Paginator.count` is supported as an asynchronous
+      method ``AsyncPaginator.acount()``.
+    * The attribute :attr:`.Paginator.num_pages` is supported as an
+      asynchronous method ``AsyncPaginator.anum_pages()``.
+    * The attribute :attr:`.Paginator.page_range` is supported as an
+      asynchronous method ``AsyncPaginator.apage_range()``.
+
+    ``AsyncPaginator`` has asynchronous versions of the same methods as
+    :class:`Paginator`, using an ``a`` prefix - for example, use
+    ``await async_paginator.aget_page(number)`` rather than
+    ``paginator.get_page(number)``.
+
 ``Page`` class
 ==============
 
@@ -226,6 +250,28 @@ Attributes
 
     The associated :class:`Paginator` object.
 
+``AsyncPage`` class
+===================
+
+.. versionadded:: 6.0
+
+.. class:: AsyncPage(object_list, number, paginator)
+
+    Asynchronous version of :class:`Page`.
+
+    ``AsyncPage`` has the same attributes and signatures as :class:`Page`, as
+    well as asynchronous versions of all the same methods, using an ``a``
+    prefix - for example, use ``await async_page.ahas_next()`` rather than
+    ``page.has_next()``.
+
+    ``AsyncPage`` has the following additional method:
+
+    .. method:: AsyncPage.aget_object_list()
+
+        Returns ``AsyncPage.object_list`` as a list. This method must be
+        awaited before ``AsyncPage`` can be treated as a sequence of
+        ``AsyncPage.object_list``.
+
 Exceptions
 ==========
 

docs/releases/6.0.txt

@@ -199,6 +199,14 @@ Models
   :ref:`a forced update <ref-models-force-insert>` results in no affected rows,
   instead of a generic :exc:`django.db.DatabaseError`.
 
+Pagination
+~~~~~~~~~~
+
+* The new :class:`~django.core.paginator.AsyncPaginator` and
+  :class:`~django.core.paginator.AsyncPage` provide async implementations of
+  :class:`~django.core.paginator.Paginator` and
+  :class:`~django.core.paginator.Page` respectively.
+
 Requests and Responses
 ~~~~~~~~~~~~~~~~~~~~~~
 

tests/pagination/custom.py

@@ -1,4 +1,4 @@
-from django.core.paginator import Page, Paginator
+from django.core.paginator import AsyncPage, AsyncPaginator, Page, Paginator
 
 
 class ValidAdjacentNumsPage(Page):
@@ -16,3 +16,20 @@ class ValidAdjacentNumsPage(Page):
 class ValidAdjacentNumsPaginator(Paginator):
     def _get_page(self, *args, **kwargs):
         return ValidAdjacentNumsPage(*args, **kwargs)
+
+
+class AsyncValidAdjacentNumsPage(AsyncPage):
+    async def anext_page_number(self):
+        if not await self.ahas_next():
+            return None
+        return await super().anext_page_number()
+
+    async def aprevious_page_number(self):
+        if not await self.ahas_previous():
+            return None
+        return await super().aprevious_page_number()
+
+
+class AsyncValidAdjacentNumsPaginator(AsyncPaginator):
+    def _get_page(self, *args, **kwargs):
+        return AsyncValidAdjacentNumsPage(*args, **kwargs)

tests/pagination/tests.py

@@ -1,9 +1,12 @@
 import collections.abc
+import inspect
 import unittest.mock
 import warnings
 from datetime import datetime
 
 from django.core.paginator import (
+    AsyncPaginator,
+    BasePaginator,
     EmptyPage,
     InvalidPage,
     PageNotAnInteger,
@@ -12,7 +15,7 @@ from django.core.paginator import (
 )
 from django.test import SimpleTestCase, TestCase
 
-from .custom import ValidAdjacentNumsPaginator
+from .custom import AsyncValidAdjacentNumsPaginator, ValidAdjacentNumsPaginator
 from .models import Article
 
 
@@ -32,6 +35,13 @@ class PaginationTests(SimpleTestCase):
         self.check_attribute("num_pages", paginator, num_pages, params)
         self.check_attribute("page_range", paginator, page_range, params, coerce=list)
 
+    async def check_paginator_async(self, params, output):
+        """See check_paginator."""
+        count, num_pages, page_range = output
+        paginator = AsyncPaginator(*params)
+        await self.check_attribute_async("acount", paginator, count, params)
+        await self.check_attribute_async("anum_pages", paginator, num_pages, params)
+
     def check_attribute(self, name, paginator, expected, params, coerce=None):
         """
         Helper method that checks a single attribute and gives a nice error
@@ -47,14 +57,21 @@ class PaginationTests(SimpleTestCase):
             % (name, expected, got, params),
         )
 
-    def test_paginator(self):
-        """
-        Tests the paginator attributes using varying inputs.
-        """
+    async def check_attribute_async(self, name, paginator, expected, params):
+        """See check_attribute."""
+        got = getattr(paginator, name)
+        self.assertEqual(
+            expected,
+            await got(),
+            "For '%s', expected %s but got %s.  Paginator parameters were: %s"
+            % (name, expected, got, params),
+        )
+
+    def get_test_cases_for_test_paginator(self):
         nine = [1, 2, 3, 4, 5, 6, 7, 8, 9]
         ten = nine + [10]
         eleven = ten + [11]
-        tests = (
+        return (
             # Each item is 2-tuple:
             #     First tuple is Paginator parameters - object_list, per_page,
             #         orphans, and allow_empty_first_page.
@@ -111,9 +128,17 @@ class PaginationTests(SimpleTestCase):
             ((ten, 4, "1", False), (10, 3, [1, 2, 3])),
             ((ten, 4, "1", False), (10, 3, [1, 2, 3])),
         )
+
+    def test_paginator(self):
+        tests = self.get_test_cases_for_test_paginator()
         for params, output in tests:
             self.check_paginator(params, output)
 
+    async def test_paginator_async(self):
+        tests = self.get_test_cases_for_test_paginator()
+        for params, output in tests:
+            await self.check_paginator_async(params, output)
+
     def test_invalid_page_number(self):
         """
         Invalid page numbers result in the correct exception being raised.
@@ -128,6 +153,12 @@ class PaginationTests(SimpleTestCase):
         with self.assertRaises(PageNotAnInteger):
             paginator.validate_number(1.2)
 
+    async def test_invalid_apage_number_async(self):
+        """See test_invalid_page_number."""
+        paginator = AsyncPaginator([1, 2, 3], 2)
+        with self.assertRaises(InvalidPage):
+            await paginator.apage(3)
+
     def test_error_messages(self):
         error_messages = {
             "invalid_page": "Wrong page number",
@@ -186,6 +217,27 @@ class PaginationTests(SimpleTestCase):
         self.assertEqual(5, paginator.num_pages)
         self.assertEqual([1, 2, 3, 4, 5], list(paginator.page_range))
 
+    async def test_paginate_misc_classes_async(self):
+        class CountContainer:
+            async def acount(self):
+                return 42
+
+        # AsyncPaginator can be passed other objects with an acount() method.
+        paginator = AsyncPaginator(CountContainer(), 10)
+        self.assertEqual(42, await paginator.acount())
+        self.assertEqual(5, await paginator.anum_pages())
+        self.assertEqual([1, 2, 3, 4, 5], list(await paginator.apage_range()))
+
+        # AsyncPaginator can be passed other objects that implement __len__.
+        class LenContainer:
+            def __len__(self):
+                return 42
+
+        paginator = AsyncPaginator(LenContainer(), 10)
+        self.assertEqual(42, await paginator.acount())
+        self.assertEqual(5, await paginator.anum_pages())
+        self.assertEqual([1, 2, 3, 4, 5], list(await paginator.apage_range()))
+
     def test_count_does_not_silence_attribute_error(self):
         class AttributeErrorContainer:
             def count(self):
@@ -194,6 +246,14 @@ class PaginationTests(SimpleTestCase):
         with self.assertRaisesMessage(AttributeError, "abc"):
             Paginator(AttributeErrorContainer(), 10).count
 
+    async def test_acount_does_not_silence_attribute_error_async(self):
+        class AttributeErrorContainer:
+            async def acount(self):
+                raise AttributeError("abc")
+
+        with self.assertRaisesMessage(AttributeError, "abc"):
+            await AsyncPaginator(AttributeErrorContainer(), 10).acount()
+
     def test_count_does_not_silence_type_error(self):
         class TypeErrorContainer:
             def count(self):
@@ -202,6 +262,14 @@ class PaginationTests(SimpleTestCase):
         with self.assertRaisesMessage(TypeError, "abc"):
             Paginator(TypeErrorContainer(), 10).count
 
+    async def test_acount_does_not_silence_type_error_async(self):
+        class TypeErrorContainer:
+            async def acount(self):
+                raise TypeError("abc")
+
+        with self.assertRaisesMessage(TypeError, "abc"):
+            await AsyncPaginator(TypeErrorContainer(), 10).acount()
+
     def check_indexes(self, params, page_num, indexes):
         """
         Helper method that instantiates a Paginator object from the passed
@@ -227,12 +295,30 @@ class PaginationTests(SimpleTestCase):
             msg % ("end index", page_num, end, page.end_index(), params),
         )
 
-    def test_page_indexes(self):
-        """
-        Paginator pages have the correct start and end indexes.
-        """
+    async def check_indexes_async(self, params, page_num, indexes):
+        """See check_indexes."""
+        paginator = AsyncPaginator(*params)
+        if page_num == "first":
+            page_num = 1
+        elif page_num == "last":
+            page_num = await paginator.anum_pages()
+        page = await paginator.apage(page_num)
+        start, end = indexes
+        msg = "For %s of page %s, expected %s but got %s. Paginator parameters were: %s"
+        self.assertEqual(
+            start,
+            await page.astart_index(),
+            msg % ("start index", page_num, start, await page.astart_index(), params),
+        )
+        self.assertEqual(
+            end,
+            await page.aend_index(),
+            msg % ("end index", page_num, end, await page.aend_index(), params),
+        )
+
+    def get_test_cases_for_test_page_indexes(self):
         ten = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
-        tests = (
+        return (
             # Each item is 3-tuple:
             #     First tuple is Paginator parameters - object_list, per_page,
             #         orphans, and allow_empty_first_page.
@@ -265,6 +351,12 @@ class PaginationTests(SimpleTestCase):
             (([], 4, 1, True), (0, 0), (0, 0)),
             (([], 4, 2, True), (0, 0), (0, 0)),
         )
+
+    def test_page_indexes(self):
+        """
+        Paginator pages have the correct start and end indexes.
+        """
+        tests = self.get_test_cases_for_test_page_indexes()
         for params, first, last in tests:
             self.check_indexes(params, "first", first)
             self.check_indexes(params, "last", last)
@@ -277,6 +369,21 @@ class PaginationTests(SimpleTestCase):
         with self.assertRaises(EmptyPage):
             self.check_indexes(([], 4, 2, False), 1, None)
 
+    async def test_page_indexes_async(self):
+        """See test_page_indexes"""
+        tests = self.get_test_cases_for_test_page_indexes()
+        for params, first, last in tests:
+            await self.check_indexes_async(params, "first", first)
+            await self.check_indexes_async(params, "last", last)
+
+        # When no items and no empty first page, we should get EmptyPage error.
+        with self.assertRaises(EmptyPage):
+            await self.check_indexes_async(([], 4, 0, False), 1, None)
+        with self.assertRaises(EmptyPage):
+            await self.check_indexes_async(([], 4, 1, False), 1, None)
+        with self.assertRaises(EmptyPage):
+            await self.check_indexes_async(([], 4, 2, False), 1, None)
+
     def test_page_sequence(self):
         """
         A paginator page acts like a standard sequence.
@@ -289,6 +396,16 @@ class PaginationTests(SimpleTestCase):
         self.assertEqual("".join(page2), "fghijk")
         self.assertEqual("".join(reversed(page2)), "kjihgf")
 
+    async def test_page_sequence_async(self):
+        eleven = "abcdefghijk"
+        page2 = await AsyncPaginator(eleven, per_page=5, orphans=1).apage(2)
+        await page2.aget_object_list()
+        self.assertEqual(len(page2), 6)
+        self.assertIn("k", page2)
+        self.assertNotIn("a", page2)
+        self.assertEqual("".join(page2), "fghijk")
+        self.assertEqual("".join(reversed(page2)), "kjihgf")
+
     def test_get_page_hook(self):
         """
         A Paginator subclass can use the ``_get_page`` hook to
@@ -303,6 +420,20 @@ class PaginationTests(SimpleTestCase):
         self.assertEqual(page2.previous_page_number(), 1)
         self.assertIsNone(page2.next_page_number())
 
+    async def test_get_page_hook_async(self):
+        """
+        An AsyncPaginator subclass can use the ``_get_page`` hook to
+        return an alternative to the standard AsyncPage class.
+        """
+        eleven = "abcdefghijk"
+        paginator = AsyncValidAdjacentNumsPaginator(eleven, per_page=6)
+        page1 = await paginator.apage(1)
+        page2 = await paginator.apage(2)
+        self.assertIsNone(await page1.aprevious_page_number())
+        self.assertEqual(await page1.anext_page_number(), 2)
+        self.assertEqual(await page2.aprevious_page_number(), 1)
+        self.assertIsNone(await page2.anext_page_number())
+
     def test_page_range_iterator(self):
         """
         Paginator.page_range should be an iterator.
@@ -323,6 +454,20 @@ class PaginationTests(SimpleTestCase):
         # Non-integer page returns the first page.
         self.assertEqual(paginator.get_page(None).number, 1)
 
+    async def test_aget_page_async(self):
+        """
+        AsyncPaginator.aget_page() returns a valid page even with invalid page
+        arguments.
+        """
+        paginator = AsyncPaginator([1, 2, 3], 2)
+        page = await paginator.aget_page(1)
+        self.assertEqual(page.number, 1)
+        self.assertEqual(page.object_list, [1, 2])
+        # An empty page returns the last page.
+        self.assertEqual((await paginator.aget_page(3)).number, 2)
+        # Non-integer page returns the first page.
+        self.assertEqual((await paginator.aget_page(None)).number, 1)
+
     def test_get_page_empty_object_list(self):
         """Paginator.get_page() with an empty object_list."""
         paginator = Paginator([], 2)
@@ -332,6 +477,15 @@ class PaginationTests(SimpleTestCase):
         # Non-integer page returns the first page.
         self.assertEqual(paginator.get_page(None).number, 1)
 
+    async def test_aget_page_empty_object_list_async(self):
+        """AsyncPaginator.aget_page() with an empty object_list."""
+        paginator = AsyncPaginator([], 2)
+        # An empty page returns the last page.
+        self.assertEqual((await paginator.aget_page(1)).number, 1)
+        self.assertEqual((await paginator.aget_page(2)).number, 1)
+        # Non-integer page returns the first page.
+        self.assertEqual((await paginator.aget_page(None)).number, 1)
+
     def test_get_page_empty_object_list_and_allow_empty_first_page_false(self):
         """
         Paginator.get_page() raises EmptyPage if allow_empty_first_page=False
@@ -341,6 +495,17 @@ class PaginationTests(SimpleTestCase):
         with self.assertRaises(EmptyPage):
             paginator.get_page(1)
 
+    async def test_aget_page_empty_obj_list_and_allow_empty_first_page_false_async(
+        self,
+    ):
+        """
+        AsyncPaginator.aget_page() raises EmptyPage if allow_empty_first_page=False
+        and object_list is empty.
+        """
+        paginator = AsyncPaginator([], 2, allow_empty_first_page=False)
+        with self.assertRaises(EmptyPage):
+            await paginator.aget_page(1)
+
     def test_paginator_iteration(self):
         paginator = Paginator([1, 2, 3], 2)
         page_iterator = iter(paginator)
@@ -353,6 +518,66 @@ class PaginationTests(SimpleTestCase):
             ["<Page 1 of 2>", "<Page 2 of 2>"],
         )
 
+    async def test_paginator_iteration_async(self):
+        paginator = AsyncPaginator([1, 2, 3], 2)
+        page_iterator = aiter(paginator)
+        for page, expected in enumerate(([1, 2], [3]), start=1):
+            with self.subTest(page=page):
+                async_page = await anext(page_iterator)
+                self.assertEqual(expected, [obj async for obj in async_page])
+        self.assertEqual(
+            [str(page) async for page in aiter(paginator)],
+            ["<Async Page 1>", "<Async Page 2>"],
+        )
+
+    def get_test_cases_for_test_get_elided_page_range(self):
+        ELLIPSIS = Paginator.ELLIPSIS
+        return [
+            # on_each_side=2, on_ends=1
+            (1, 2, 1, [1, 2, 3, ELLIPSIS, 50]),
+            (4, 2, 1, [1, 2, 3, 4, 5, 6, ELLIPSIS, 50]),
+            (5, 2, 1, [1, 2, 3, 4, 5, 6, 7, ELLIPSIS, 50]),
+            (6, 2, 1, [1, ELLIPSIS, 4, 5, 6, 7, 8, ELLIPSIS, 50]),
+            (45, 2, 1, [1, ELLIPSIS, 43, 44, 45, 46, 47, ELLIPSIS, 50]),
+            (46, 2, 1, [1, ELLIPSIS, 44, 45, 46, 47, 48, 49, 50]),
+            (47, 2, 1, [1, ELLIPSIS, 45, 46, 47, 48, 49, 50]),
+            (50, 2, 1, [1, ELLIPSIS, 48, 49, 50]),
+            # on_each_side=1, on_ends=3
+            (1, 1, 3, [1, 2, ELLIPSIS, 48, 49, 50]),
+            (5, 1, 3, [1, 2, 3, 4, 5, 6, ELLIPSIS, 48, 49, 50]),
+            (6, 1, 3, [1, 2, 3, 4, 5, 6, 7, ELLIPSIS, 48, 49, 50]),
+            (7, 1, 3, [1, 2, 3, ELLIPSIS, 6, 7, 8, ELLIPSIS, 48, 49, 50]),
+            (44, 1, 3, [1, 2, 3, ELLIPSIS, 43, 44, 45, ELLIPSIS, 48, 49, 50]),
+            (45, 1, 3, [1, 2, 3, ELLIPSIS, 44, 45, 46, 47, 48, 49, 50]),
+            (46, 1, 3, [1, 2, 3, ELLIPSIS, 45, 46, 47, 48, 49, 50]),
+            (50, 1, 3, [1, 2, 3, ELLIPSIS, 49, 50]),
+            # on_each_side=4, on_ends=0
+            (1, 4, 0, [1, 2, 3, 4, 5, ELLIPSIS]),
+            (5, 4, 0, [1, 2, 3, 4, 5, 6, 7, 8, 9, ELLIPSIS]),
+            (6, 4, 0, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, ELLIPSIS]),
+            (7, 4, 0, [ELLIPSIS, 3, 4, 5, 6, 7, 8, 9, 10, 11, ELLIPSIS]),
+            (44, 4, 0, [ELLIPSIS, 40, 41, 42, 43, 44, 45, 46, 47, 48, ELLIPSIS]),
+            (45, 4, 0, [ELLIPSIS, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50]),
+            (46, 4, 0, [ELLIPSIS, 42, 43, 44, 45, 46, 47, 48, 49, 50]),
+            (50, 4, 0, [ELLIPSIS, 46, 47, 48, 49, 50]),
+            # on_each_side=0, on_ends=1
+            (1, 0, 1, [1, ELLIPSIS, 50]),
+            (2, 0, 1, [1, 2, ELLIPSIS, 50]),
+            (3, 0, 1, [1, 2, 3, ELLIPSIS, 50]),
+            (4, 0, 1, [1, ELLIPSIS, 4, ELLIPSIS, 50]),
+            (47, 0, 1, [1, ELLIPSIS, 47, ELLIPSIS, 50]),
+            (48, 0, 1, [1, ELLIPSIS, 48, 49, 50]),
+            (49, 0, 1, [1, ELLIPSIS, 49, 50]),
+            (50, 0, 1, [1, ELLIPSIS, 50]),
+            # on_each_side=0, on_ends=0
+            (1, 0, 0, [1, ELLIPSIS]),
+            (2, 0, 0, [1, 2, ELLIPSIS]),
+            (3, 0, 0, [ELLIPSIS, 3, ELLIPSIS]),
+            (48, 0, 0, [ELLIPSIS, 48, ELLIPSIS]),
+            (49, 0, 0, [ELLIPSIS, 49, 50]),
+            (50, 0, 0, [ELLIPSIS, 50]),
+        ]
+
     def test_get_elided_page_range(self):
         # Paginator.validate_number() must be called:
         paginator = Paginator([1, 2, 3], 2)
@@ -426,51 +651,7 @@ class PaginationTests(SimpleTestCase):
                         self.assertIn(ELLIPSIS, page_range)
 
         # Range should be elided if enough pages when using custom arguments:
-        tests = [
-            # on_each_side=2, on_ends=1
-            (1, 2, 1, [1, 2, 3, ELLIPSIS, 50]),
-            (4, 2, 1, [1, 2, 3, 4, 5, 6, ELLIPSIS, 50]),
-            (5, 2, 1, [1, 2, 3, 4, 5, 6, 7, ELLIPSIS, 50]),
-            (6, 2, 1, [1, ELLIPSIS, 4, 5, 6, 7, 8, ELLIPSIS, 50]),
-            (45, 2, 1, [1, ELLIPSIS, 43, 44, 45, 46, 47, ELLIPSIS, 50]),
-            (46, 2, 1, [1, ELLIPSIS, 44, 45, 46, 47, 48, 49, 50]),
-            (47, 2, 1, [1, ELLIPSIS, 45, 46, 47, 48, 49, 50]),
-            (50, 2, 1, [1, ELLIPSIS, 48, 49, 50]),
-            # on_each_side=1, on_ends=3
-            (1, 1, 3, [1, 2, ELLIPSIS, 48, 49, 50]),
-            (5, 1, 3, [1, 2, 3, 4, 5, 6, ELLIPSIS, 48, 49, 50]),
-            (6, 1, 3, [1, 2, 3, 4, 5, 6, 7, ELLIPSIS, 48, 49, 50]),
-            (7, 1, 3, [1, 2, 3, ELLIPSIS, 6, 7, 8, ELLIPSIS, 48, 49, 50]),
-            (44, 1, 3, [1, 2, 3, ELLIPSIS, 43, 44, 45, ELLIPSIS, 48, 49, 50]),
-            (45, 1, 3, [1, 2, 3, ELLIPSIS, 44, 45, 46, 47, 48, 49, 50]),
-            (46, 1, 3, [1, 2, 3, ELLIPSIS, 45, 46, 47, 48, 49, 50]),
-            (50, 1, 3, [1, 2, 3, ELLIPSIS, 49, 50]),
-            # on_each_side=4, on_ends=0
-            (1, 4, 0, [1, 2, 3, 4, 5, ELLIPSIS]),
-            (5, 4, 0, [1, 2, 3, 4, 5, 6, 7, 8, 9, ELLIPSIS]),
-            (6, 4, 0, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, ELLIPSIS]),
-            (7, 4, 0, [ELLIPSIS, 3, 4, 5, 6, 7, 8, 9, 10, 11, ELLIPSIS]),
-            (44, 4, 0, [ELLIPSIS, 40, 41, 42, 43, 44, 45, 46, 47, 48, ELLIPSIS]),
-            (45, 4, 0, [ELLIPSIS, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50]),
-            (46, 4, 0, [ELLIPSIS, 42, 43, 44, 45, 46, 47, 48, 49, 50]),
-            (50, 4, 0, [ELLIPSIS, 46, 47, 48, 49, 50]),
-            # on_each_side=0, on_ends=1
-            (1, 0, 1, [1, ELLIPSIS, 50]),
-            (2, 0, 1, [1, 2, ELLIPSIS, 50]),
-            (3, 0, 1, [1, 2, 3, ELLIPSIS, 50]),
-            (4, 0, 1, [1, ELLIPSIS, 4, ELLIPSIS, 50]),
-            (47, 0, 1, [1, ELLIPSIS, 47, ELLIPSIS, 50]),
-            (48, 0, 1, [1, ELLIPSIS, 48, 49, 50]),
-            (49, 0, 1, [1, ELLIPSIS, 49, 50]),
-            (50, 0, 1, [1, ELLIPSIS, 50]),
-            # on_each_side=0, on_ends=0
-            (1, 0, 0, [1, ELLIPSIS]),
-            (2, 0, 0, [1, 2, ELLIPSIS]),
-            (3, 0, 0, [ELLIPSIS, 3, ELLIPSIS]),
-            (48, 0, 0, [ELLIPSIS, 48, ELLIPSIS]),
-            (49, 0, 0, [ELLIPSIS, 49, 50]),
-            (50, 0, 0, [ELLIPSIS, 50]),
-        ]
+        tests = self.get_test_cases_for_test_get_elided_page_range()
         paginator = Paginator(range(5000), 100)
         for number, on_each_side, on_ends, expected in tests:
             with self.subTest(
@@ -484,6 +665,94 @@ class PaginationTests(SimpleTestCase):
                 self.assertIsInstance(page_range, collections.abc.Generator)
                 self.assertEqual(list(page_range), expected)
 
+    async def test_aget_elided_page_range_async(self):
+        # AsyncPaginator.avalidate_number() must be called:
+        paginator = AsyncPaginator([1, 2, 3], 2)
+        with unittest.mock.patch.object(paginator, "avalidate_number") as mock:
+            mock.assert_not_called()
+            [p async for p in paginator.aget_elided_page_range(2)]
+            mock.assert_called_with(2)
+
+        ELLIPSIS = Paginator.ELLIPSIS
+
+        # Range is not elided if not enough pages when using default arguments:
+        paginator = AsyncPaginator(range(10 * 100), 100)
+        page_range = paginator.aget_elided_page_range(1)
+        self.assertIsInstance(page_range, collections.abc.AsyncGenerator)
+        self.assertNotIn(ELLIPSIS, [p async for p in page_range])
+        paginator = AsyncPaginator(range(10 * 100 + 1), 100)
+        self.assertIsInstance(page_range, collections.abc.AsyncGenerator)
+        page_range = paginator.aget_elided_page_range(1)
+        self.assertIn(ELLIPSIS, [p async for p in page_range])
+
+        # Range should be elided if enough pages when using default arguments:
+        tests = [
+            # on_each_side=3, on_ends=2
+            (1, [1, 2, 3, 4, ELLIPSIS, 49, 50]),
+            (6, [1, 2, 3, 4, 5, 6, 7, 8, 9, ELLIPSIS, 49, 50]),
+            (7, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, ELLIPSIS, 49, 50]),
+            (8, [1, 2, ELLIPSIS, 5, 6, 7, 8, 9, 10, 11, ELLIPSIS, 49, 50]),
+            (43, [1, 2, ELLIPSIS, 40, 41, 42, 43, 44, 45, 46, ELLIPSIS, 49, 50]),
+            (44, [1, 2, ELLIPSIS, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50]),
+            (45, [1, 2, ELLIPSIS, 42, 43, 44, 45, 46, 47, 48, 49, 50]),
+            (50, [1, 2, ELLIPSIS, 47, 48, 49, 50]),
+        ]
+        paginator = AsyncPaginator(range(5000), 100)
+        for number, expected in tests:
+            with self.subTest(number=number):
+                page_range = paginator.aget_elided_page_range(number)
+                self.assertIsInstance(page_range, collections.abc.AsyncGenerator)
+                self.assertEqual([p async for p in page_range], expected)
+
+        # Range is not elided if not enough pages when using custom arguments:
+        tests = [
+            (6, 2, 1, 1),
+            (8, 1, 3, 1),
+            (8, 4, 0, 1),
+            (4, 1, 1, 1),
+            # When on_each_side and on_ends are both <= 1 but not both == 1 it
+            # is a special case where the range is not elided until an extra
+            # page is added.
+            (2, 0, 1, 2),
+            (2, 1, 0, 2),
+            (1, 0, 0, 2),
+        ]
+        for pages, on_each_side, on_ends, elided_after in tests:
+            for offset in range(elided_after + 1):
+                with self.subTest(
+                    pages=pages,
+                    offset=elided_after,
+                    on_each_side=on_each_side,
+                    on_ends=on_ends,
+                ):
+                    paginator = AsyncPaginator(range((pages + offset) * 100), 100)
+                    page_range = paginator.aget_elided_page_range(
+                        1,
+                        on_each_side=on_each_side,
+                        on_ends=on_ends,
+                    )
+                    self.assertIsInstance(page_range, collections.abc.AsyncGenerator)
+                    page_list = [p async for p in page_range]
+                    if offset < elided_after:
+                        self.assertNotIn(ELLIPSIS, page_list)
+                    else:
+                        self.assertIn(ELLIPSIS, page_list)
+
+        # Range should be elided if enough pages when using custom arguments:
+        tests = self.get_test_cases_for_test_get_elided_page_range()
+        paginator = AsyncPaginator(range(5000), 100)
+        for number, on_each_side, on_ends, expected in tests:
+            with self.subTest(
+                number=number, on_each_side=on_each_side, on_ends=on_ends
+            ):
+                page_range = paginator.aget_elided_page_range(
+                    number,
+                    on_each_side=on_each_side,
+                    on_ends=on_ends,
+                )
+                self.assertIsInstance(page_range, collections.abc.AsyncGenerator)
+                self.assertEqual([p async for p in page_range], expected)
+
 
 class ModelPaginationTests(TestCase):
     """
@@ -513,6 +782,21 @@ class ModelPaginationTests(TestCase):
         self.assertEqual(1, p.start_index())
         self.assertEqual(5, p.end_index())
 
+    async def test_first_page_async(self):
+        paginator = AsyncPaginator(Article.objects.order_by("id"), 5)
+        p = await paginator.apage(1)
+        self.assertEqual("<Async Page 1>", str(p))
+        object_list = await p.aget_object_list()
+        self.assertSequenceEqual(object_list, self.articles[:5])
+        self.assertTrue(await p.ahas_next())
+        self.assertFalse(await p.ahas_previous())
+        self.assertTrue(await p.ahas_other_pages())
+        self.assertEqual(2, await p.anext_page_number())
+        with self.assertRaises(InvalidPage):
+            await p.aprevious_page_number()
+        self.assertEqual(1, await p.astart_index())
+        self.assertEqual(5, await p.aend_index())
+
     def test_last_page(self):
         paginator = Paginator(Article.objects.order_by("id"), 5)
         p = paginator.page(2)
@@ -527,6 +811,21 @@ class ModelPaginationTests(TestCase):
         self.assertEqual(6, p.start_index())
         self.assertEqual(9, p.end_index())
 
+    async def test_last_page_async(self):
+        paginator = AsyncPaginator(Article.objects.order_by("id"), 5)
+        p = await paginator.apage(2)
+        self.assertEqual("<Async Page 2>", str(p))
+        object_list = await p.aget_object_list()
+        self.assertSequenceEqual(object_list, self.articles[5:])
+        self.assertFalse(await p.ahas_next())
+        self.assertTrue(await p.ahas_previous())
+        self.assertTrue(await p.ahas_other_pages())
+        with self.assertRaises(InvalidPage):
+            await p.anext_page_number()
+        self.assertEqual(1, await p.aprevious_page_number())
+        self.assertEqual(6, await p.astart_index())
+        self.assertEqual(9, await p.aend_index())
+
     def test_page_getitem(self):
         """
         Tests proper behavior of a paginator page __getitem__ (queryset
@@ -551,6 +850,24 @@ class ModelPaginationTests(TestCase):
         # After __getitem__ is called, object_list is a list
         self.assertIsInstance(p.object_list, list)
 
+    async def test_page_getitem_async(self):
+        paginator = AsyncPaginator(Article.objects.order_by("id"), 5)
+        p = await paginator.apage(1)
+
+        msg = "AsyncPage indices must be integers or slices, not str."
+        with self.assertRaisesMessage(TypeError, msg):
+            p["has_previous"]
+
+        self.assertIsNone(p.object_list._result_cache)
+
+        self.assertNotIsInstance(p.object_list, list)
+
+        await p.aget_object_list()
+
+        self.assertEqual(p[0], self.articles[0])
+        self.assertSequenceEqual(p[slice(2)], self.articles[:2])
+        self.assertIsInstance(p.object_list, list)
+
     def test_paginating_unordered_queryset_raises_warning(self):
         msg = (
             "Pagination may yield inconsistent results with an unordered "
@@ -562,11 +879,27 @@ class ModelPaginationTests(TestCase):
         # is appropriate).
         self.assertEqual(cm.filename, __file__)
 
+    async def test_paginating_unordered_queryset_raises_warning_async(self):
+        msg = (
+            "Pagination may yield inconsistent results with an unordered "
+            "object_list: <class 'pagination.models.Article'> QuerySet."
+        )
+        with self.assertWarnsMessage(UnorderedObjectListWarning, msg) as cm:
+            AsyncPaginator(Article.objects.all(), 5)
+        # The warning points at the BasePaginator caller.
+        # The reason is that the UnorderedObjectListWarning occurs in BasePaginator.
+        self.assertEqual(cm.filename, inspect.getfile(BasePaginator))
+
     def test_paginating_empty_queryset_does_not_warn(self):
         with warnings.catch_warnings(record=True) as recorded:
             Paginator(Article.objects.none(), 5)
         self.assertEqual(len(recorded), 0)
 
+    async def test_paginating_empty_queryset_does_not_warn_async(self):
+        with warnings.catch_warnings(record=True) as recorded:
+            AsyncPaginator(Article.objects.none(), 5)
+        self.assertEqual(len(recorded), 0)
+
     def test_paginating_unordered_object_list_raises_warning(self):
         """
         Unordered object list warning with an object that has an ordered
@@ -583,3 +916,58 @@ class ModelPaginationTests(TestCase):
         )
         with self.assertWarnsMessage(UnorderedObjectListWarning, msg):
             Paginator(object_list, 5)
+
+    async def test_paginating_unordered_object_list_raises_warning_async(self):
+        """
+        See test_paginating_unordered_object_list_raises_warning.
+        """
+
+        class ObjectList:
+            ordered = False
+
+        object_list = ObjectList()
+        msg = (
+            "Pagination may yield inconsistent results with an unordered "
+            "object_list: {!r}.".format(object_list)
+        )
+        with self.assertWarnsMessage(UnorderedObjectListWarning, msg):
+            AsyncPaginator(object_list, 5)
+
+    async def test_async_page_object_list_raises_type_error_before_await(self):
+        paginator = AsyncPaginator(Article.objects.order_by("id"), 5)
+        p = await paginator.apage(1)
+
+        with self.subTest(func="len"):
+            msg = "AsyncPage.aget_object_list() must be awaited before calling len()."
+            with self.assertRaisesMessage(TypeError, msg):
+                len(p)
+
+        with self.subTest(func="reversed"):
+            msg = (
+                "AsyncPage.aget_object_list() must be awaited before calling "
+                "reversed()."
+            )
+            with self.assertRaisesMessage(TypeError, msg):
+                reversed(p)
+
+        with self.subTest(func="index"):
+            msg = "AsyncPage.aget_object_list() must be awaited before using indexing."
+            with self.assertRaisesMessage(TypeError, msg):
+                p[0]
+
+    async def test_async_page_aiteration(self):
+        paginator = AsyncPaginator(Article.objects.order_by("id"), 5)
+        p = await paginator.apage(1)
+        object_list = [obj async for obj in p]
+        self.assertEqual(len(object_list), 5)
+
+    async def test_aget_object_list(self):
+        paginator = AsyncPaginator(Article.objects.order_by("id"), 5)
+        p = await paginator.apage(1)
+
+        # object_list queryset is converted to list.
+        first_called_objs = await p.aget_object_list()
+        self.assertIsInstance(first_called_objs, list)
+        # It returns the same list that was converted on the first call.
+        second_called_objs = await p.aget_object_list()
+        self.assertEqual(id(first_called_objs), id(second_called_objs))